@article{yang_warchol_cunningham_hummer_2023, title={The potential of signalized offset T-intersections to accommodate new developments}, volume={12}, ISSN={["2046-0449"]}, DOI={10.1016/j.ijtst.2022.01.006}, abstractNote={An offset T-intersection splits a conventional four leg intersection into two three-leg T-intersections to reduce the number of conflicts. While the safety benefits of offset T-intersections have been widely documented, the effects on operations are not well understood. To fix that, this paper employed microsimulation modeling to investigate the differences in operational performance between offset T-intersections and four-leg standard intersections under various traffic demands, intersection spacings, and signal timing schemes for three development types: superstore, hybrid gas station, and residential area. Queue length and delay were employed as measurements of effectiveness. Based on microsimulation modeling, we found that under most of the tested scenarios, offset T-intersections were superior to four-leg intersections in terms of reducing delay for the main street traffic. In addition, we found that the left–right (L-R) offset T-intersection configuration outperformed the right-left (R-L) offset configuration in terms of preventing main-street left turn queue spillback. Based on the simulation results, the paper provided practice-ready guidelines on selecting an optimum intersection configuration for each specific development type given the volume demands and known geometric constraints for a given site.}, number={1}, journal={INTERNATIONAL JOURNAL OF TRANSPORTATION SCIENCE AND TECHNOLOGY}, author={Yang, Guangchuan and Warchol, Shannon and Cunningham, Christopher M. and Hummer, Joseph}, year={2023}, month={Mar}, pages={217–229} }
 @article{zahabi_pankok_kaber_machado_lau_hummer_rasdorf_2017, title={On-Road Visual Sign Salience, Driver Attention Allocation, and Target Detection Accuracy}, ISSN={["2169-4052"]}, DOI={10.3141/2663-06}, abstractNote={Previous studies have empirically assessed the effect of on-road signage on driver distraction and attention allocation through eye-tracking measures and driving simulations. However, state and federal agencies might be able to make use of simpler approaches to determining the potential visual load of on-road signs. This study compared different on-road signage (food, gas and attraction, and distance guide signs) with respect to visual salience, assessed the effect of the number of panels and logo format on signage salience, and analyzed associations between salience values for different sign types with target detection accuracy and off-road glance duration. Visual salience of signs was measured with the salience using the natural statistics (SUNs) method. For correlation analyses between sign salience, attention allocation, and detection accuracy, a sample of 120 drivers participated in two driving simulation studies. Results revealed food business signs, containing all pictorial logos, to be more salient than gas and attraction and distance guide signs. In addition, results revealed that increasing the number of sign panels from six to nine significantly increased visual salience. It was also found that attraction signs including all pictorial logos were more salient than signs with text-based logos. Results did not reveal statistically significant relationships between visual salience and attention allocation. In addition, there was no significant correlation between target detection accuracy and visual salience for various sign types. Future work with a higher sign-sampling rate is needed to assess whether the SUNs method is a useful measure for determining if roadway sign salience is a driving factor in distraction.}, number={2663}, journal={TRANSPORTATION RESEARCH RECORD}, author={Zahabi, Maryam and Pankok, Carl, Jr. and Kaber, David B. and Machado, Patricia and Lau, Mei Ying and Hummer, Joseph E. and Rasdorf, William}, year={2017}, pages={40–47} }
 @article{arocho_rasdorf_hummer_lewis_2017, title={Time and cost characterisation of emissions from non-road diesel equipment for infrastructure projects}, volume={10}, ISSN={["1939-7046"]}, DOI={10.1080/19397038.2016.1218569}, abstractNote={Abstract The construction process contributes to pollutant emissions, particularly through the operation of diesel- and gasoline-powered equipment. In the past decade, a series of investigations were undertaken to quantify these emissions for a variety of non-road construction equipment performing different activities and undergoing different duty cycles, and a model to estimate quantities of six types of pollutant was developed. This paper uses that model to estimate emissions for four street and utility construction projects which no one has done previously. We combined information from company records with standard construction industry manuals to estimate total emissions for the projects and to examine the pollution patterns and magnitudes. The street construction projects all had similar emission profiles with a large peak at the beginning and a steady output of emissions throughout the duration of the project. For example, in two of the projects studied, half of all CO2 emissions were produced before the projects were 40% completed. Results showed that demolition and earthwork are the activities with the largest contribution. The equipment types with the largest contribution are backhoes, front-end loaders, bulldozers and trenchers. Trenchers, for example, produced 30% of all emissions on the projects on which they were used.}, number={2}, journal={INTERNATIONAL JOURNAL OF SUSTAINABLE ENGINEERING}, author={Arocho, Ingrid and Rasdorf, William and Hummer, Joseph and Lewis, Phil}, year={2017}, pages={123–134} }
 @article{findley_hummer_rasdorf_laton_2013, title={Collecting Horizontal Curve Data: Mobile Asset Vehicles and Other Techniques}, volume={19}, ISSN={["1076-0342"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000316563500008&KeyUID=WOS:000316563500008}, DOI={10.1061/(asce)is.1943-555x.0000107}, abstractNote={Mobile asset data collection vehicles can provide transportation agencies with inventories of various roadway and roadside elements containing location information, element type, and condition data. Horizontal curves are of interest to agencies because they have been shown to be hazardous roadway components and have potential for mobile data collection concurrently with other roadway elements. The cost of manually acquiring horizontal curvature data to develop an inventory can be prohibitive for many agencies, so understanding the applicability of a mobile asset data collection effort for curves is important. The objective of this work was to study the ability of multiple commercial roadway inventory vehicles and to compare them to other methods for determining the geometric characteristics of horizontal curves. The comparison is based on data from three commercial vendors of roadway asset inventory data on a 38.8-km (24.1-mi) course in central North Carolina. Among the 16 curves studied, at least one vendor was within 10% of the radius value found with the manual chord method for six of the curves and within 25% for 13 of the curves. Only three curves had a larger radius variant. For the length measurements of the 16 curves, at least one vendor was within 10% of the length from the chord method for eleven of the curves and within 25% for fifteen of the curves. Only one curve had a larger length variant. The mobile vehicle vendors provided more accurate and consistent curve length measurements than radius measurements. Agencies that consider using mobile data collection vehicles for horizontal alignments should understand the limitations of each horizontal curve estimating technique and the changes that can occur in the radius within the curve. Collaborating with vendors to define the changes in roadway alignment that constitute a curve, the associated beginning and ending of the curve, and geometric characteristics can provide agencies the most appropriate data to meet their needs.}, number={1}, journal={JOURNAL OF INFRASTRUCTURE SYSTEMS}, author={Findley, Daniel J. and Hummer, Joseph E. and Rasdorf, William and Laton, Brian T.}, year={2013}, month={Mar}, pages={74–84} }
 @article{zhang_harris_rogers_kaber_hummer_rasdorf_hu_2013, title={Driver distraction and performance effects of highway logo sign design}, volume={44}, ISSN={["1872-9126"]}, DOI={10.1016/j.apergo.2012.10.009}, abstractNote={Driver distraction and safety concerns have been identified for new highway logo sign configurations. This study assessed driver perception of logo signs and distraction under nine-panel, overflow-combination, or standard six-panel formats. A nine-panel sign has nine business panels within a single sign; a six-panel sign has six panels within a sign; an overflow-combination consists of a standard six-panel sign and a six-panel sign displaying two different services (e.g., food and gas). In this study, twenty-four participants searched for target food business logos while driving in a high-fidelity driving simulation under each signage condition. Gas and lodging signs were also displayed along the road in conventional six-panel formats. Dependent variables included signal detection, visual attention allocation, and vehicle control measures. Experiment results showed nine-panel signs drew greater visual attention and produced lower average speed than overflow-combination signs, and produced a lower speeding percentage compared to six-panel signs. However, there was no evidence the new configurations (nine-panel and overflow) caused substantive performance changes with safety implications. This study suggested the use of nine-panel and overflow-combination logo signs may be suitable for interchanges where there are more than six qualifying businesses in a category in terms of driver performance and safety.}, number={3}, journal={APPLIED ERGONOMICS}, author={Zhang, Yu and Harris, Elizabeth and Rogers, Meghan and Kaber, David and Hummer, Joseph and Rasdorf, William and Hu, Jia}, year={2013}, month={May}, pages={472–479} }
 @article{hollar_rasdorf_liu_hummer_arocho_hsiang_2013, title={Preliminary Engineering Cost Estimation Model for Bridge Projects}, volume={139}, ISSN={0733-9364 1943-7862}, url={http://dx.doi.org/10.1061/(asce)co.1943-7862.0000668}, DOI={10.1061/(asce)co.1943-7862.0000668}, abstractNote={AbstractThis paper addresses one of the costs of new bridges, i.e., the cost of doing the preliminary engineering (PE). This particular aspect of cost has largely been neglected because of the difficulty in obtaining appropriate data. Typically, PE costs are determined as a percentage of construction costs, disregarding other project-specific parameters. Bridge projects let by the North Carolina (NC) DOT between 2001 and 2009 were reviewed. From an analysis of these 461 projects, the writers developed statistical models linking variation in PE costs with distinctive project parameters. The primary contribution this paper makes to the body of knowledge is the finding that PE cost estimates for bridge projects are commonly and significantly underestimated. The writers found that bridge projects exhibited a mean PE cost ratio of 28%. This result is significantly greater than the percentage used in practice. An investigation of data sources related to bridge projects, a description of regression techniques ap...}, number={9}, journal={Journal of Construction Engineering and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Hollar, Donna A. and Rasdorf, William and Liu, Min and Hummer, Joseph E. and Arocho, Ingrid and Hsiang, Simon M.}, year={2013}, month={Sep}, pages={1259–1267} }
 @article{liu_rasdorf_hummer_hollar_parikh_2013, title={Preliminary Engineering Cost-Estimation Strategy Assessment for Roadway Projects}, volume={29}, ISSN={0742-597X 1943-5479}, url={http://dx.doi.org/10.1061/(asce)me.1943-5479.0000137}, DOI={10.1061/(asce)me.1943-5479.0000137}, abstractNote={Preliminary engineering (PE) for a roadway project encompasses two efforts: planning to minimize the physical, social, and human environmental impacts of projects and engineering design to deliver the best alternative. State transportation agencies strive to manage these efforts efficiently, seeking to maximize the utilization of limited funding and workforce productivity. Managers need a feasible PE budget, considering both cost and time, early in project development. The results reported herein will provide engineers and managers with a comparative investigation evaluating different strategies for establishing a PE budget during the preconstruction phase of roadway project development. Cost data were obtained for 188 North Carolina roadway projects built between 1999 and 2009. An analysis of the North Carolina DOT data yielded an overall mean ratio of PE cost to estimated construction cost (the PE cost ratio) of 11.7%. The multiple linear regression model was used to develop prediction models to forecast the PE cost ratio of future roadway projects. It was found that while differing regression strategies could reduce prediction error, the improvement was small. In terms of simplicity, using the historical means applicable for widening projects (13.3%), rehabilitation/resurfacing projects (7.7%), and new location/interchange projects (16.5%) proved advantageous over regression modeling because a project manager would not have to estimate any project-specific values at the earliest stages of project development. The lowest of these historical means was significantly different than the two higher means (7.7% versus 13.3% and 16.5%); however, the difference between the two higher means (13.3% versus 16.5%) was not statistically significant. The study analyses also found a significant correlation between a project’s PE cost ratio and its PE duration, suggesting that further investigation into PE duration of transportation projects is warranted.}, number={2}, journal={Journal of Management in Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Liu, Min and Rasdorf, William and Hummer, Joseph E. and Hollar, Donna A. and Parikh, Shalin C.}, year={2013}, month={Apr}, pages={150–157} }
 @article{hummer_harris_rasdorf_2013, title={Simulation-Based Evaluation of Traffic Sign Retroreflectivity Maintenance Practices}, volume={139}, ISSN={["0733-947X"]}, DOI={10.1061/(asce)te.1943-5436.0000526}, abstractNote={A new highway sign minimum retroreflectivity standard issued by the Federal Highway Administration (FHWA) is compelling agencies to evaluate how to comply while remaining within their budgets. This paper presents the results from a unique microscopic sign system simulation developed to quantitatively evaluate the effectiveness of various sign management practices. The analysis focused on three management methods—nighttime visual inspection, blanket replacement, and expected sign life—and two key sign maintenance functions, sign damage and replacement. The analysis found that sign managers should make prompt replacement of damaged signs a priority. The blanket replacement method was less cost-effective than the nighttime visual inspection method. The expected sign life method was competitive on costs with the visual inspection method while maintaining similar sign conditions. Training inspectors to be more accurate can realize further savings. Skipping inspection or replacement one year, or having an insufficient sign budget, can lead to degraded sign condition levels. The authors offer five best practices that agencies can consider when making sign management decisions.}, number={6}, journal={JOURNAL OF TRANSPORTATION ENGINEERING-ASCE}, author={Hummer, Joseph E. and Harris, Elizabeth A. and Rasdorf, William}, year={2013}, month={Jun}, pages={556–564} }
 @article{harris_rasdorf_hummer_2012, title={Development of a Microscopic Simulation to Model Traffic Sign Management and Performance}, volume={26}, ISSN={["0887-3801"]}, DOI={10.1061/(asce)cp.1943-5487.0000126}, abstractNote={Minimum retroreflectivity standards issued by the Federal Highway Administration (FHWA) have focused the attention of highway administrators on improving the nighttime performance of signs. This paper outlines the development of a microscopic sign management simulation that facilitates predicting an agency’s level of compliance with the standards and determining the cost of compliance. Using the Arena simulation software, the authors built a model in which each sign was represented as a separate entity and moved through a network of submodels replicating the management and environmental processes experienced annually. The simulation includes submodels for sign damage, inspection, replacement, and deterioration that are modifiable by key input parameters. The simulation model produces several key estimates on an annual basis for the purpose of comparing different sign management scenarios. The resulting model was validated and used to evaluate a scenario representing management conditions in North Carolina...}, number={2}, journal={JOURNAL OF COMPUTING IN CIVIL ENGINEERING}, author={Harris, Elizabeth A. and Rasdorf, William and Hummer, Joseph E.}, year={2012}, pages={172–182} }
 @article{rasdorf_findley_zegeer_sundstrom_hummer_2012, title={Evaluation of GIS Applications for Horizontal Curve Data Collection}, volume={26}, ISSN={["1943-5487"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000302218800005&KeyUID=WOS:000302218800005}, DOI={10.1061/(asce)cp.1943-5487.0000127}, abstractNote={Applications that use a geographic information system (GIS) are common and useful in the field of transportation. Horizontal curves are critical components on a roadway in their role as a transition between straight segments and in their potential as a safety hazard to motorists. Therefore, determining the characteristics of curves [both spatial (including location, length, radius) and nonspatial (including traffic volume, signage, pavement type)] is an important task. GIS applications have been developed for evaluating roadway alignments in general and some have focused on horizontal curve assessment. This paper reports on two benchmarking efforts. The first assessed and established the accuracy of three publicly available GIS applications for determining curve spatial characteristics. The second assessed the quality of available GIS roadway line work. The three GIS applications were evaluated for performance accuracy on the basis of a comparison with precisely drawn curves [with radii ranging from 30.5 ...}, number={2}, journal={JOURNAL OF COMPUTING IN CIVIL ENGINEERING}, author={Rasdorf, William and Findley, Daniel J. and Zegeer, Charles V. and Sundstrom, Carl A. and Hummer, Joseph E.}, year={2012}, pages={191–203} }
 @article{ott_haley_hummer_foyle_cunningham_2012, title={Safety effects of unsignalized superstreets in North Carolina}, volume={45}, journal={Accident Analysis and Prevention}, author={Ott, S. E. and Haley, R. L. and Hummer, J. E. and Foyle, R. S. and Cunningham, C. M.}, year={2012}, pages={572–579} }
 @article{findley_cunningham_hummer_2011, title={Comparison of mobile and manual data collection for roadway components}, volume={19}, ISSN={["0968-090X"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000288637400011&KeyUID=WOS:000288637400011}, DOI={10.1016/j.trc.2010.08.002}, abstractNote={The primary objective of this research effort was to compare roadside data collected by typical manual methods – on foot and often requiring traffic control – to data collected by manned data collection vehicles moving with traffic. The research team provided an unbiased comparison of multiple vendors collecting many types of data on various roadway elements including curb, guardrail, signs, pavement markings, and roadway geometry. These data are frequently collected and used by many units within a highway agency such as roadway maintenance, safety, and operations. The research team provided a catalog to each vendor prior to running a 144.8 km (90-mile) test course. The catalog provided a map of the course, a list of each roadway element to be collected, and specific details on how each data element was collected manually. The test course included a variety of highways across a portion of central North Carolina. Multiple data collection companies were given the opportunity to participate, with six actually agreeing to partake and submit data. No vendors supplied sign retroreflectivity data, one submitted pavement marking retroreflectivity data, three submitted roadway geometry data, and five submitted data on roadside elements. The results showed that mobile data compared reasonably well to manual data for most of the desired variables. Mobile data on elements in close proximity to the edge of pavement matched manual data better than elements further from the road. Counts of specific elements were a better fit between mobile and manual data than elements that needed qualitative judgments. Among the major lessons learned is the need for crystal clear specifications before embarking on a mobile data collection program and the desirability of having vendors submit data for a small sample of roadway before embarking on the bulk of a data collection effort.}, number={3}, journal={TRANSPORTATION RESEARCH PART C-EMERGING TECHNOLOGIES}, author={Findley, Daniel J. and Cunningham, Christopher M. and Hummer, Joseph E.}, year={2011}, month={Jun}, pages={521–540} }
 @article{hummer_rasdorf_zhang_2011, title={Linear Mixed-Effects Models for Paint Pavement-Marking Retroreflectivity Data}, volume={137}, ISSN={["1943-5436"]}, DOI={10.1061/(asce)te.1943-5436.0000283}, abstractNote={The objective of this paper is to present an improved paint pavement-marking retroreflectivity degradation model. Previous degradation-modeling methods were reviewed and studied. The paint-marking retroreflectivity data were collected on 25 two-lane rural highways in North Carolina from November 2007 to May 2010. A linear mixed-effects model (LMEM) was selected as most appropriate for the paint-marking retroreflectivity data. The LMEM took into account the correlation among repeated measurements of the data set and produced more accurate predictions than other methods. LMEMs were established for white edge and yellow center paint pavement markings. The LMEM results showed that the estimated white edge pavement marking life cycle is 37.5 months and yellow center marking life cycle is 38.9 months on average when using 100 and 65  mcd/m2/lx as the minimum acceptable retroreflectivity values for white and yellow paint markings. A model comparison indicated that the LMEM provided a more accurate prediction tha...}, number={10}, journal={JOURNAL OF TRANSPORTATION ENGINEERING}, author={Hummer, Joseph E. and Rasdorf, William and Zhang, Guanghua}, year={2011}, month={Oct}, pages={705–716} }
 @article{haley_ott_hummer_foyle_cunningham_schroeder_2011, title={Operational effects of signalized superstreets in North Carolina}, number={2223}, journal={Transportation Research Record}, author={Haley, R. L. and Ott, S. E. and Hummer, J. E. and Foyle, R. S. and Cunningham, C. M. and Schroeder, B. J.}, year={2011}, pages={72–79} }
 @article{moon_hummer_van duyn_2011, title={Saving space in a dense city: When designers should consider the new nano-interchange}, volume={15}, number={6}, journal={KSCE Journal of Civil Engineering}, author={Moon, J. P. and Hummer, J. E. and Van Duyn, M. H.}, year={2011}, pages={1101–1108} }
 @inproceedings{hummer_rasdorf_findley_zegeer_sundstrom_2010, title={An examination of horizontal curve collisions characteristics and corresponding countermeasures}, booktitle={Proceedings of the Transportation Research Board 89th Annual Meeting}, publisher={Washington, D.C. : Transportation Research Board}, author={Hummer, J. E. and Rasdorf, W. and Findley, D. J. and Zegeer, C. V. and Sundstrom, C. A.}, year={2010} }
 @article{hummer_rasdorf_findley_zegeer_sundstrom_2010, title={Curve collisions: Road and collision characteristics and countermeasures}, volume={2}, ISBN={NULL}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79958270365&partnerID=MN8TOARS}, DOI={10.1080/19439961003734880}, abstractNote={Horizontal curves are relatively dangerous portions of roadway networks. Agencies optimizing the use of safety funds should be aware of characteristics of the collisions on those segments. However, few previously published articles attempted to characterize collisions on horizontal curves. This article describes an effort that characterized collisions reported to be on curves in North Carolina using the Highway Safety Information System. More than 51,000 North Carolina (NC) collisions on two-lane road curves were compared to collisions on all two-lane roads and on all roads. In doing so we gained a perspective of how well various curves perform relative to other road areas. We investigated numerous two-lane curve-collision types. Those most overrepresented included: collisions on grades, rural, severe injury or fatal, fixed object (particularly tree, ditch, and embankment), overturn, off-peak hours (particularly during darkness on unlighted roads), weekend, holiday periods, and wet, icy, or snowy pavement. The analysis also revealed that there were few short roadway segments (of 0.1- to 1-mile length) with more than 10 reported curve collisions in 3 years. This article provides recommendations from the literature to treat overrepresented collision types on horizontal curves. Based on the analysis findings, agencies should target countermeasures for the most common and overrepresented collision types.}, number={3}, journal={Journal of Transportation Safety and Security}, author={Hummer, J.E. and Rasdorf, W. and Findley, Daniel and Zegeer, C.V. and Sundstrom, C.A.}, year={2010}, pages={203–220} }
 @inproceedings{hollar_arocho_hummer_liu_rasdorf_2010, title={Development of a regression model to predict preliminary engineering costs}, ISBN={9781933452517}, booktitle={ITE 2010 Technical Conference and Exhibit compendium of technical papers}, publisher={Washington, D.C. : Institute of Transportation Engineers}, author={Hollar, D. and Arocho, I. and Hummer, J. and Liu, M. and Rasdorf, W.}, year={2010} }
 @article{zhang_hummer_rasdorf_2010, title={Impact of Bead Density on Paint Pavement Marking Retroreflectivity}, volume={136}, ISSN={["1943-5436"]}, DOI={10.1061/(asce)te.1943-5436.0000142}, abstractNote={This paper addresses the impact of bead density on paint pavement marking retroreflectivity. The writers collected retroreflectivity data and glass bead images on 40 segments of two-lane highways. Bead density is defined as the surface percentage of glass beads exposed above the paint marking material. Numerous methods for determining bead density were considered and studied. A new approach, referred to as a computer-aided counting method, was developed and a bead density analysis program was written. The program was used to analyze 108 images to obtain a bead density value for each image. A correlation study was conducted between pavement marking retroreflectivity and bead density. The findings of the study show that the normal range of glass bead density for older markings is 9–24% of the paint marking surface area. Furthermore, bead density values have a positive correlation with marking retroreflectivity readings; higher bead density leads to higher retroreflectivity. White paint markings have significantly higher retroreflectivity values than do yellow markings when the bead density values are the same.}, number={8}, journal={JOURNAL OF TRANSPORTATION ENGINEERING}, author={Zhang, Guanghua and Hummer, Joseph E. and Rasdorf, William}, year={2010}, month={Aug}, pages={773–781} }
 @book{engagement_2010, title={Integrating learning, discovery, and engagement through the scholarship of engagement}, journal={Technical Report- Not held in TRLN member libraries}, institution={Raleigh, NC: NCSU Office of Extension, Engagement, and Economic Development}, author={Engagement, Task Force}, year={2010} }
 @article{moon_hummer_2010, title={Speed enforcement cameras in Charlotte, North Carolina estimation of longer-term safety effects}, number={2182}, journal={Transportation Research Record}, author={Moon, J. P. and Hummer, J. E.}, year={2010}, pages={31–39} }
 @article{harris_rasdorf_hummer_2009, title={A Control Sign Facility Design to Meet the New FHWA Minimum Sign Retroreflectivity Standards}, volume={14}, ISSN={["1552-7549"]}, DOI={10.1177/1087724x09350226}, abstractNote={ Minimum sign retroreflectivity standards issued by the Federal Highway Administration (FHWA) on January 29, 2008, have focused the attention of administrators and sign managers on improving the nighttime performance of traffic signs. To predict when a sign will need replacement, an agency will need to know when the retroreflectivity of signs with similar characteristics deteriorate to the minimum level established by the FHWA. Currently in the literature, there is limited information about the long-term deterioration behavior of ASTM Type III and IX signs. One way of achieving a better understanding of long-term sign deterioration is to establish an experimental sign retroreflectivity measurement facility (ESRMF). An ESRMF is an arrangement of signs in a controlled area that have their retroreflectivity measured at regular intervals to determine how it deteriorates as a function of time. This article shows how such a facility should look and why. A template is presented that can be used by agencies nationwide for collecting critical sign data to inform policy decisions. }, number={2}, journal={PUBLIC WORKS MANAGEMENT & POLICY}, author={Harris, Elizabeth A. and Rasdorf, William and Hummer, Joseph E.}, year={2009}, month={Oct}, pages={174–194} }
 @article{sitzabee_rasdorf_hummer_devine_2009, title={Data integration of pavement markings: A case in transportation asset management}, volume={23}, DOI={10.1061/(ASCE)0887-3801(2009)23:5(288)}, abstractNote={Effective transportation asset management requires the implementation of tools such as software, hardware, databases, and data collection systems. Pavement markings make up one component in transportation asset management, which are complex networks that require large databases. Typically these databases are maintained in different areas within an agency and are most often incompatible. Combining new and old tools, this paper addresses the need for better data integration and utilization while incorporating current information technologies. Specifically, this paper presents integrated transportation asset management system for estimating the current and future condition of pavement markings. The paper describes the data structure, in the form of a physical model, integrating a pavement marking relational data schema with existing information technology systems. Software was found to be useful in developing the data schema. The software produced an extensible markup language file that is compatible with a variety of existing database structures such as Oracle, SQL, and MS Access. Additionally, the system included an algorithm, which implements the data structure and predictive models to estimate the condition of the asset at any point in time or space on the highway system. Using either measured data or predicted data the system gives managers an opportunity to decide on the best possible condition state of the asset and perform queries or optimizations. Ultimately, managers can develop cost effective strategies for pavement marking asset management.}, number={5}, journal={Journal of Computing in Civil Engineering}, author={Sitzabee, W. E. and Rasdorf, W. and Hummer, J. E. and Devine, H. A.}, year={2009}, pages={288–298} }
 @article{rasdorf_hummer_harris_sitzabee_2009, title={IT Issues for the management of high-quantity, low-cost assets}, volume={23}, DOI={10.1061/(asce)0887-3801(2009)23:2(91)}, abstractNote={Transportation infrastructure asset management efforts have historically focused on collecting data on assets with high capital costs, such as bridges and pavements. Road signs and pavement markings, on the other hand, are high quantity, low capital cost assets but are also critical elements of the transportation infrastructure. These high quantity assets serve a critical function, safety, and thus they are receiving attention. Mandated by law, the Federal Highway Administration has been working to establish minimum retroreflectivity standards for signs and pavement markings. This paper seeks to address the information technology (IT) problems that emerge when developing an overall asset management system for high-quantity, low-cost assets. These IT problems include asset identification, asset location, data availability, data fragmentation, and automated data collection. A discussion of the issues related to these problems is presented to promote awareness of the myriad problems that do exist and to facilitate the development of more comprehensive systems to manage the automation of infrastructure asset management systems.}, number={2}, journal={Journal of Computing in Civil Engineering}, author={Rasdorf, W. and Hummer, J. E. and Harris, E. A. and Sitzabee, W. E.}, year={2009}, pages={91–99} }
 @book{rasdorf_hummer_zhang_sitzabee_2009, title={Pavement marking performance analysis}, journal={Technical Report- Not held in TRLN member libraries}, institution={Raleigh, N.C.:  North Carolina Department of Transportation}, author={Rasdorf, W. and Hummer, J. E. and Zhang, G. and Sitzabee, W. E.}, year={2009} }
 @article{immaneni_hummer_rasdorf_harris_yeom_2009, title={Synthesis of sign deterioration rates across the United States}, volume={135}, DOI={10.1061/(ASCE)0733-947X(2009)135:3(94)}, abstractNote={In response to minimum retroreflectivity standards, transportation departments are implementing sign asset management strategies, which rely upon knowledge of how retroreflectivity decreases as signs weather and age. To provide this knowledge, the writers field measured over 1,000 in-service signs in scattered North Carolina Department of Transportation (NCDOT) divisions, collecting age and retroreflectivity data for white, yellow, red, and green signs and for ASTM sheeting Types I and III. Data from this study and data from five similar U.S. efforts were analyzed using regression to identify the best available deterioration rate estimates, finding that retroreflectivity minimums are usually reached eight to 15 years after installation. Initial results indicated that the best-fitting relationships between retroreflectivity and age were generally linear and that these models were significant despite having low R2 values. Because age did not explain some of the variance, the writers reevaluated their data i...}, number={3}, journal={Journal of Transportation Engineering}, author={Immaneni, V. P. K. and Hummer, J. E. and Rasdorf, W. J. and Harris, E. A. and Yeom, C.}, year={2009}, pages={94–103} }
 @article{rasdorf_zhang_hummer_2009, title={The Impact of Directionality on Paint Pavement Marking Retroreflectivity}, volume={13}, ISSN={["1552-7549"]}, DOI={10.1177/1087724x08330824}, abstractNote={ This article addresses paint centerline pavement marking retroreflectivity. The authors collect yellow centerline retroreflectivity data on two-lane highways, taking measurements in two directions. A paired t test on the data shows that there are differences and they are statistically significant. A field study is initiated to investigate the relationship between the direction the marking is painted and the retroreflectivity direction. The key result of this study is that paint centerline retroreflectivity values measured in the direction of paint striping are significantly higher than values measured in the opposite direction. Findings indicate that it is the lower retroreflectivity values of yellow centerlines (measured in the opposite direction from paint striping) that should be used to compare with the newly proposed Federal Highway Administration minimum standard because the drivers in that direction experience lower marking retroreflectivity at night. The implications for safety, for policy making, and for transportation asset management are significant. }, number={3}, journal={PUBLIC WORKS MANAGEMENT & POLICY}, author={Rasdorf, William J. and Zhang, Guanghua and Hummer, Joseph E.}, year={2009}, month={Jan}, pages={265–277} }
 @article{cunningham_hummer_moon_2008, title={Analysis of Automated Speed Enforcement Cameras in Charlotte, North Carolina}, ISSN={["2169-4052"]}, DOI={10.3141/2078-17}, abstractNote={ The effects of a mobile automated speed enforcement system in Charlotte, North Carolina, were examined. Limited focus groups were conducted to characterize resident and professional attitudes, opinions, and beliefs regarding such a speed program. Overall, opinions were positive. The system, consisting of three mobile units, was implemented along 14 corridors. Two separate analyses were conducted on data collected from January 2000 to December 2005. Findings from a previous study done for the North Carolina Governor's Highway Safety Program were updated. The first, and primary, analysis was a before-and-after analysis of collisions. This study used Hauer's comparison group methodology. Three different collision data sets were analyzed: total collisions, data accounting for regression to the mean, and data for five heavily enforced corridors. On the basis of the analysis, the impact of regression to the mean appears to be negligible. The results indicate that the camera program likely reduced collisions in corridors with automated enforcement. The second analysis observed whether compliance with posted speed limits was enhanced. Mean speeds, median speeds, 85th percentile speeds, and percentages of drivers more than 10 mph over the speed limit were analyzed. The analyses found speed reductions caused by the camera program. On the basis of these findings, it was recommend that the City of Charlotte continue the automated speed enforcement program. Other agencies considering speed camera programs can benefit from the knowledge gained in Charlotte. }, number={2078}, journal={TRANSPORTATION RESEARCH RECORD}, author={Cunningham, Christopher M. and Hummer, Joseph E. and Moon, Jae-Pil}, year={2008}, pages={127–134} }
 @article{baek_hummer_2008, title={Collision Models for Multilane Highway Segments to Examine Safety of Curbs}, ISSN={["2169-4052"]}, DOI={10.3141/2083-15}, abstractNote={ The objective of this study was to develop valid statistical collision models for multilane highway segments to examine the safety of curbs. For this, road geometric traffic and collision data for 2001 to 2003 were collected. The data included 2,274 collisions and 885 injury collisions that occurred on 191.85 mi of 199 directional segments in North Carolina. The authors applied a new modeling method of introducing variables into the model one by one in a multiplicative form. A nonlinear optimizing algorithm for estimating parameters using a negative binomial log likelihood function was adopted for the modeling. The functional form of the variable to be introduced was determined on the basis of the relationship between the recorded number of collisions and the number of collisions predicted by the current model without the variable. The integrate-differentiate method was applied to find candidate functional forms for each variable. Model selections were based on the −2 log likelihood and Bayesian information criterion statistics, and the cumulative residuals plot method to check the goodness of fit of the models was adopted. As a result of the modeling efforts, the annual average daily traffic, access point density, shoulder width, and shoulder type (including curb presence) variables were introduced to the final model for total collisions. The same variables except the shoulder type variable were introduced to the injury collision model. Overall, then, it appears that curbs mean fewer total collisions and no change in injury collisions as compared to no curbs on the sampled road segments. }, number={2083}, journal={TRANSPORTATION RESEARCH RECORD}, author={Baek, Jongdae and Hummer, Joseph E.}, year={2008}, pages={128–136} }
 @article{hummer_maripalli_2008, title={Laboratory test of driver responses to nine-panel logo signs}, number={2056}, journal={Transportation Research Record}, author={Hummer, J. E. and Maripalli, U. K.}, year={2008}, pages={52–59} }
 @article{harris_rasdorf_hummer_2008, title={New standards, new signs: Determining sign performance under controlled conditions}, volume={46}, number={1}, journal={IMSA Journal}, author={Harris, E. and Rasdorf, W. and Hummer, J. E.}, year={2008}, pages={44–55} }
 @article{kiattikomol_chatterjee_hummer_younger_2008, title={Planning level regression models for prediction of crashes on interchange and noninterchange segments of urban freeways}, volume={134}, DOI={10.1061/(ASCE)0733-947X(2008)134:3(111)}, abstractNote={The need for safety assessment tools for long-range transportation planning at statewide and metropolitan levels received serious recognition when the Transportation Equity Act for Twenty First Century established a requirement related to safety considerations in the planning process of metropolitan planning organizations (MPO) and state Departments of Transportation. The latest legislation titled “Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users” also has confirmed this requirement. However, most MPOs do not currently assess the safety consequences of alternative transportation systems, and one of the reasons is the lack of suitable methodology. The goal of the research on which this paper is based was to develop practical tools for assessing safety consequences of freeways in the context of long-range urban transportation plans. Data for crashes, identified by freeway segments, were obtained from the North Carolina Department of Transportation and Tennessee Department...}, number={3}, journal={Journal of Transportation Engineering}, author={Kiattikomol, V. and Chatterjee, A. and Hummer, J. E. and Younger, M. S.}, year={2008}, pages={111–117} }
 @article{harris_rasdorf_hummer_yeom_2007, title={Analysis of traffic sign asset management scenarios}, ISSN={["0361-1981"]}, DOI={10.3141/1993-02}, abstractNote={ Minimum traffic sign retroreflectivity standards proposed for the Manual on Uniform Traffic Control Devices by the FHWA will present numerous management challenges to state and local departments of transportation (DOTs) responsible for traffic sign assets. These DOTs are looking at how to comply with the standard while minimizing sign maintenance costs. This paper presents an analysis of several traffic sign retroreflectivity maintenance methods using a sign asset management simulation based on inspection and sign data gathered in the field. The simulation evaluated 30 sign asset management scenarios in terms of annual maintenance cost per sign and percentage of traffic signs not compliant with the proposed FHWA standard. The simulation results found that, generally, higher costs for sign maintenance resulted in a lower percentage of noncompliant signs. However, for some scenarios using the visual nighttime inspection method, lower percentages of noncompliant signs were found even with relatively low maintenance costs per sign. Increasing the maintenance cost per sign by 10% resulted in an approximately 10% or more reduction in the number of noncompliant signs. It is recommended that DOTs implement a 100% Type III sign replacement policy because Type I signs have a greater life-cycle cost than do Type III signs. DOTs need to allocate an adequate annual budget for sign replacement and should establish their own minimum retroreflectivity standards. The sign asset management simulation developed as part of this study could be modified so that its use could be extended to other DOTs. }, number={1993}, journal={TRANSPORTATION RESEARCH RECORD}, author={Harris, Elizabeth Allison and Rasdorf, William and Hummer, Joseph E. and Yeom, Chunho}, year={2007}, pages={9–15} }
 @article{murphy_hummer_2007, title={Development of crash reduction factors for overhead flashing beacons at rural intersections in North Carolina}, number={2030}, journal={Transportation Research Record}, author={Murphy, B. G. and Hummer, J. E.}, year={2007}, pages={15–21} }
 @article{immaneni_rasdorf_hummer_yeom_2007, title={FIELD INVESTIGATION OF HIGHWAY SIGN DAMAGE RATES AND INSPECTOR ACCURACY}, volume={11}, ISSN={["1552-7549"]}, DOI={10.1177/1087724x07299882}, abstractNote={ This study sought to create a simulation model to provide the North Carolina Department of Transportation (NCDOT) with recommendations to improve its sign inspection and replacement procedures. This research focuses on two key factors built into the model: (a) the rate at which signs are damaged beyond usefulness based on natural or man-made causes and (b) the accuracy rate of visual sign inspections based on retroreflectivity. The research team conducted nighttime rides with sign inspectors in 5 of 14 NCDOT divisions. During subsequent daytime rides, the team measured sign retroreflectivity to allow estimation of sign deterioration and inspector accuracy rates. Data were collected for white, yellow, red, and green signs and for sheeting Types I and III. About 2.3% of inspected signs (per year) were damaged to the point of needing replacement, and inspectors did not reject a large percentage of signs that had retroreflectivity values below the proposed minimum Federal Highway Administration standard. }, number={4}, journal={PUBLIC WORKS MANAGEMENT & POLICY}, author={Immaneni, Venkata Pavan K. and Rasdorf, William J. and Hummer, Joseph E. and Yeom, Chunho}, year={2007}, month={Apr}, pages={266–278} }
 @inproceedings{rasdorf_hummer_harris_2007, title={IT infrastructure problems for asset management}, ISBN={0784409374}, DOI={10.1061/40937(261)10}, abstractNote={Transportation infrastructure asset management efforts normally focus on collecting data on items with low volumes and higher capital costs, such as bridges. Road signs and pavement markings, on the other hand, are high volume, low capital cost items but are critical elements of the transportation infrastructure. These high volume assets serve a critical function, safety, and thus they are receiving attention. In particular, the Federal Highway Administration (FHWA) has been working to establish minimum retroreflectivity standards for signs and pavement markings. This paper seeks to address information technology (IT) problems that emerge when developing an overall asset management system for high volume assets and to identify their unique characteristics. These IT problems include asset identification, asset location, data availability, data fragmentation, automated data collection, software selection, and system size and resources. A discussion of the issues related to these problems is presented herein to facilitate the development of more comprehensive systems to manage the automation of infrastructure asset management systems (AMS).}, booktitle={Computing in civil engineering: Proceedings of the 2007 ASCE International Workshop on Computing in Civil Engineering, July 24-27, 2007, Pittsburgh, Pennsylvania}, publisher={Reston, VA: American Society of Civil Engineers}, author={Rasdorf, W. and Hummer, J. and Harris, E.}, editor={L. Soibelman, B. Akinci and Shon, H.Editors}, year={2007} }
 @article{craig_sitzabee_rasdorf_hummer_2007, title={STATISTICAL VALIDATION OF THE EFFECT OF LATERAL LINE LOCATION ON PAVEMENT MARKING RETROREFLECTIVITY DEGRADATION}, volume={12}, ISSN={["1552-7549"]}, DOI={10.1177/1087724x07308773}, abstractNote={ This article examines the effect of lateral location on the degradation of retroreflectivity in thermoplastic pavement-marking systems. The authors examined data collected on North Carolina roads over a 5-year period and conducted a statistical analysis to determine if there was a significant difference in the rates of retroreflectivity degradation between edge lines and center lines. The study concluded that there was statistical evidence that lateral line location does have an effect on retroreflectivity degradation and that center lines degrade faster than edge lines. Understanding retroreflectivity performance over time facilitates the development and implementation of guidelines and tools that can be used for holistic asset management. Based on their findings, the authors recommend changes in pavement-marking maintenance strategies. }, number={2}, journal={PUBLIC WORKS MANAGEMENT & POLICY}, author={Craig, W. Neil, III and Sitzabee, William E. and Rasdorf, William J. and Hummer, Joseph E.}, year={2007}, month={Oct}, pages={431–450} }
 @article{williams_tagliaferri_meinhold_hummer_rouphail_2007, title={Simulation and analysis of freeway lane reversal for coastal hurricane evacuation}, volume={133}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33847207471&partnerID=MN8TOARS}, DOI={10.1061/(ASCE)0733-9488(2007)133:1(61)}, abstractNote={Following the unprecedented multistate evacuation for Hurricane Floyd in 1999, the North Carolina Department of Transportation and the Department of Crime Control and Public Safety jointly developed a lane reversal plan for Interstate 40 to facilitate evacuation of residents and tourists in southeastern North Carolina. Prior to the 2003 hurricane season, the NCDOT sponsored a two-year research to address areas of operational concern. The first year research findings resulted in modifications to the original lane reversal plan. The second year's findings showed the modified reversal plan to be effective in expediting evacuation from the coastal threat zone. However, modeling of the entire lane reversal plan revealed a potentially extensive queue formation at the contraflow termination point. This paper presents an overview of the project along with the principal research findings and resulting plan modifications. In addition, this paper highlights conclusions and recommendations applicable to the general emergency evacuation problem.}, number={1}, journal={Journal of Urban Planning and Development}, author={Williams, Billy and Tagliaferri, A.P. and Meinhold, S.S. and Hummer, J.E. and Rouphail, N.M.}, year={2007}, pages={61–72} }
 @book{rasdorf_hummer_harris_immaneni_yeom_2006, title={Designing a nighttime sign inspection procedure to ensure motorist safety}, number={FHWA/NC 2006-08}, journal={Technical Report- Not held in TRLN member libraries}, institution={Raleigh, N.C.:  North Carolina Department of Transportation}, author={Rasdorf, W. and Hummer, J. and Harris, E. and Immaneni, V. and Yeom, C.}, year={2006} }
 @book{hummer_rasdorf_harris_2006, title={Designing an experimental facility for roadway sign retroreflectivity measurement}, number={TA-2006-06}, journal={Technical Report- Not held in TRLN member libraries}, institution={Raleigh, N.C.:  Department of Civil Engineering, North Carolina State University}, author={Hummer, J. and Rasdorf, W. and Harris, E.}, year={2006} }
 @inbook{baek_hummer_williams_cunningham_2006, title={Reasonable speed limits on suburban multilane highways with curbs}, ISBN={0309099781}, number={1969}, booktitle={Highway safety: law enforcement; alcohol; driver training; safety planning and management; commercial vehicles; and motorcycles}, publisher={Washington: Transportation Research Board Natl Research Council}, author={Baek, J. and Hummer, J. E. and Williams, B. M. and Cunningham, C. M.}, year={2006}, pages={10–17} }
 @inbook{carter_hummer_foyle_phillips_2005, title={Operational and safety effects of U-turns at signalized intersections}, ISBN={0309093856}, number={1912}, booktitle={Geometric design and the effects on traffic operations, 2005}, publisher={Washington, DC: Transportation Research Board}, author={Carter, D. and Hummer, J. E. and Foyle, R. S. and Phillips, S.}, year={2005}, pages={11–18} }
 @article{rasdorf_hummer_vereen_cai_2005, title={Quantitative evaluation of the nighttime visual inspection method of sign evaluation}, volume={14}, number={1}, journal={Journal of the Transportation Research Forum}, author={Rasdorf, W. and Hummer, J. and Vereen, S. and Cai, H.}, year={2005}, pages={121–139} }
 @inbook{hummer_rouphail_hughes_fain_toole_patten_schneider_monahan_do_2005, title={User perceptions of the quality of service on shared paths}, ISBN={0309094135}, number={1939}, booktitle={Bicycles and pedestrians:  Developing countries, 2005}, publisher={Washington, D.C.: Transportation Research Board}, author={Hummer, J. E. and Rouphail, N. and Hughes, R. G. and Fain, S. J. and Toole, J. L. and Patten, R. S. and Schneider, R. J. and Monahan, J. F. and Do, A.}, year={2005}, pages={28–36} }
 @article{vereen_hummer_rasdorf_2004, title={Alternative approaches for state agencies to address the proposed minimum retroreflectivity standards}, volume={8}, DOI={10.1177/1087724x04263208}, abstractNote={ This work aimed to determine, quantify, and present alternative approaches for agencies to meet the Federal Highway Administration's (FHWA) proposed minimum levels of retroreflectivity for signs. This study based these approaches on current North Carolina Department of Transportation sign maintenance practices and sought to minimize the cost and labor required to meet FHWA standards. This article offers four approaches: Nighttime visual inspection (current method), improved nighttime visual inspection procedures, sign inventory management system (no visual inspection), and combination of alternatives #2 and #3. This study ultimately recommends alternative #4, although it is the most costly. This article also recommends that an evaluation be made periodically to determine what benefits and improvement in sign condition, if any, have resulted from implementation. }, number={4}, journal={Public Works Management & Policy}, author={Vereen, S. and Hummer, J. and Rasdorf, W.}, year={2004}, pages={235–248} }
 @inbook{thompson_hummer_kluckman_2003, title={Comparison of the new W-interchange with conventional interchanges}, ISBN={0309085837}, number={1847}, booktitle={Operational effects of geometrics, 2003}, publisher={Washington, DC: Transportation Research Board}, author={Thompson, C. D. and Hummer, J. E. and Kluckman, R. C.}, year={2003}, pages={42–51} }
 @book{vereen_hummer_rasdorf_2002, title={A sign inventory study to assess and control liability and cost}, number={FHWA/NC 2002-16}, journal={Technical Report- Not held in TRLN member libraries}, institution={Raleigh, N.C.: North Carolina Department of Transportation}, author={Vereen, S. and Hummer, J. E. and Rasdorf, W.}, year={2002} }
 @inbook{reid_hummer_2001, title={Travel time comparisons between seven unconventional arterial intersection designs}, ISBN={0309072123}, number={1751}, booktitle={Geometric design and the effects on traffic operations 2001}, publisher={Washington, DC: National Academy Press}, author={Reid, J. D. and Hummer, J. E.}, year={2001}, pages={56–66} }
 @inbook{brown_hummer_2000, title={Determining the best method for measuring no-passing zones}, ISBN={0309066808}, number={1701}, booktitle={Pavement management and monitoring}, publisher={Washington, DC: National Academy Press}, author={Brown, R. L. and Hummer, J. E.}, year={2000}, pages={61–67} }
 @article{karimi_khattak_hummer_2000, title={Evaluation of mobile mapping systems for roadway data collection}, volume={14}, DOI={10.1061/(ASCE)0887-3801(2000)14:3(168)}, abstractNote={Mobile mapping systems (MMSs) are based on advanced technologies for automatically collecting roadway inventory data. A host of advanced technologies, such as the Global Positioning System for collecting georeferencing data and digital cameras for collecting roadway data, are used in current MMSs. An MMS is driven on a subject roadway, collecting positional data and digital images of the roadway. Through photogrammetric software packages, roadway data are extracted from images. Although there have been studies evaluating the accuracy of positional data collected by MMSs, there have been limited studies of the descriptive data accuracy they provide. In this paper the results of an evaluation of the accuracy of descriptive inventory data collected by three different MMSs are discussed. Each system was tested in three different roadway environments, and five different types of inventory elements were included in each test. The accuracy of collected data was compared with ground truth data. Analysis of these data indicated that the roadway environment and the type of inventory element affect the accuracy of descriptive inventory data collected by MMSs.}, number={3}, journal={Journal of Computing in Civil Engineering}, author={Karimi, H. A. and Khattak, A. J. and Hummer, J. E.}, year={2000}, pages={168–173} }
 @inbook{wissinger_hummer_milazzo_2000, title={Using focus groups to investigate issues of red light running}, ISBN={0309067359}, number={1734}, booktitle={Highway and traffic safety: Engineering, evaluation, and enforcement; trucking and motorcycles: safety and human performance}, publisher={Washington, DC: National Academy Press}, author={Wissinger, L. M. and Hummer, J. E. and Milazzo, J. S.}, year={2000}, pages={38–45} }
 @article{dai_karimi_khorram_khattak_hummer_1999, title={Roadway feature extraction and delineation fron high-resolution satellite imagery}, number={1999 May}, journal={EOM}, author={Dai, X. L. and Karimi, H. A. and Khorram, S. and Khattak, A. J. and Hummer, J. E.}, year={1999}, pages={34–37} }
 @article{karimi_dai_khattak_khorram_hummer_1999, title={Techniques for automated extraction of roadway inventory features from high-resolution satellite imagery}, volume={14}, DOI={10.1080/10106049908542099}, abstractNote={Abstract The emergence of high‐resolution satellite imagery is attracting new applications which can take advantage of remotely sensed data for mapping, inventory, and change detection. Automated collection of roadway inventory features is one such application. To this end, it is important to investigate the performance of conventional feature extraction techniques when applied to high‐resolution images and to develop new techniques for extraction of roadway features using one‐meter, or higher, resolution imagery. In this paper, classification‐ based and edge detection‐based techniques potential for automated extraction of roadway features from high‐resolution satellite imagery are described, tested, and evaluated. Of possible techniques, the applicability of conventional classification algorithms, the Thin and Robust Zero‐Crossing edge detector based on the Laplacian of Gaussian operator, and seeded region growing segmentation is investigated. The advantages and disadvantages of each technique for extrac...}, number={2}, journal={Geocarto International}, author={Karimi, H. A. and Dai, X. L. and Khattak, A. J. and Khorram, S. and Hummer, J. E.}, year={1999}, pages={5–16} }
 @book{hummer_1998, title={Accidents on secondary highways and counter-measures}, publisher={Knoxville, TN: University of Tennessee Transportation Center}, author={Hummer, J. E.}, year={1998} }
 @inproceedings{accidents on secondary highways and counter-measures: phase i, final report_1998, publisher={Raleigh, NC: Southeastern Transportation Center Consortium}, year={1998} }
 @inproceedings{hummer_khattak_1998, title={Analysis of major types of collisions on two-lane rural highways in North Carolina}, number={1998}, booktitle={1998 Compendium of technical papers, Institute of Transportation Engineers, 68th annual meeting, Toronto, Ontario, August 12}, author={Hummer, J. E. and Khattak, A. J.}, year={1998} }
 @article{khattak_hummer_1998, title={Analysis of run off the road collisions on two lane rural highways in North Carolina, USA}, volume={68}, number={10}, journal={ITE Journal}, author={Khattak, A. J. and Hummer, J. E.}, year={1998}, pages={1818} }
 @inproceedings{khattak_hummer_1998, title={Analysis of run off the road collisions on two lane rural highways in North Carolina, USA}, number={1998 Aug.}, booktitle={1998 compendium of technical papers, Institute of Transportation Engineers, 68th Annual Meeting, Toronto, Ontario, August 1998}, author={Khattak, A. J. and Hummer, J. E.}, year={1998} }
 @inbook{allen_hummer_rouphail_milazzo_1998, title={Effect of bicycles on capacity of signalized intersections}, ISBN={0309065186}, number={1646}, booktitle={Highway capacity issues, 1998}, publisher={Washington, DC: Transportation Research Board}, author={Allen, D. P. and Hummer, J. E. and Rouphail, N. M. and Milazzo, J. S.}, year={1998}, pages={87–95} }
 @inbook{milazzo_rouphail_hummer_allen_1998, title={Effect of pedestrians on capacity of signalized intersections}, ISBN={0309065186}, number={1646}, booktitle={Highway capacity issues, 1998}, publisher={Washington, DC: Transportation Research Board}, author={Milazzo, J. S. and Rouphail, N. M. and Hummer, J. E. and Allen, D. P.}, year={1998}, pages={37–46} }
 @article{khattak_karimi_dai_hummer_1998, title={High-resolution satellite imagery aids roadway data collection}, number={1998 Nov.}, journal={Public Works}, author={Khattak, A. J. and Karimi, H. A. and Dai, X. L. and Hummer, J. E.}, year={1998}, pages={28–30} }
 @inbook{allen_rouphail_hummer_milazzo_1998, title={Operational analysis of uninterrupted bicycle facilities}, ISBN={0309065089}, number={1636}, booktitle={Bicycle and pedestrian research, 1998}, publisher={Washington, DC: Transportation Research Board}, author={Allen, D. P. and Rouphail, N. and Hummer, J. E. and Milazzo, J. S.}, year={1998}, pages={29–36} }
 @inproceedings{rouphail_hummer_goldblatt_1998, title={Pedestrian and bicycle impacts on signalized intersection operations: the U.S. experience}, volume={2}, number={1998}, booktitle={Proceedings of the Third International Symposium on Highway Capacity, Copenhagen, Denmark, June 22-27, 1998}, author={Rouphail, N. M. and Hummer, J. E. and Goldblatt, R.}, year={1998}, pages={852–872} }
 @article{karimi_dai_khatak_hummer_1998, title={The emergence of high-resolution satellite digital imagery for acquisition roadway inventory features}, volume={3}, number={1}, journal={Space Energy and Transportation}, author={Karimi, H. A. and Dai, X. L. and Khatak, A. J. and Hummer, J. E.}, year={1998}, pages={19–26} }
 @article{hummer_1998, title={Unconventional left-turn alternatives for urban and suburban arterials: Part one}, volume={68}, number={9}, journal={ITE Journal}, author={Hummer, J. E.}, year={1998}, pages={26–29} }
 @inbook{rouphail_hummer_allen_1997, title={Bicycle operations and level of service literature synthesis}, booktitle={Final Draft, Federal Highway Administration, McLean, VA, January 1997}, author={Rouphail, N. M. and Hummer, J. E. and Allen, D. P.}, year={1997} }
 @article{hummer_graham_ravoori_king_rogers_1997, title={Classifying unlighted roadways based on night to total accident ratios}, volume={26}, ISSN={["0099-4480"]}, DOI={10.1080/00994480.1997.10748190}, number={2}, journal={JOURNAL OF THE ILLUMINATING ENGINEERING SOCIETY}, author={Hummer, JE and Graham, JR and Ravoori, SB and King, LE and Rogers, MD}, year={1997}, pages={49-+} }
 @inbook{karimi_hummer_1997, title={Collection and presentation of roadway inventory data}, booktitle={Interim Report, National Cooperative Highway Research Program Project 1515, Transportation Research Board, Washington, DC, May 1997}, publisher={Washington, DC: Transportation Research Board}, author={Karimi, H. A. and Hummer, J. E.}, year={1997} }
 @inproceedings{hummer_khattak_kantor_1997, title={Collision factors and potential counter measures related to heavy trucks on two-lane roads}, number={1997}, booktitle={Proceedings, 1997 International Large Truck Safety Symposium, Knoxville, TN, October 27-29}, author={Hummer, J. E. and Khattak, A. and Kantor, P.}, year={1997}, pages={81–91} }
 @inbook{chatterjee_hummer_clarke_ney_1997, title={Landside access to sea ports in urban areas: A case study}, ISBN={0309062047}, number={1602}, booktitle={Truck, marine, and intermodal freight and hazardous materials transportation}, publisher={Washington, DC: Transportation Research Board}, author={Chatterjee, A. and Hummer, J. E. and Clarke, D. B. and Ney, S. M.}, year={1997}, pages={49–56} }
 @inbook{hummer_1997, title={Planning and engineering studies}, booktitle={Traffic sign handbook (Ch. 4)}, publisher={Washington, DC: Institute of Transportation Engineers}, author={Hummer, J. E.}, year={1997} }
 @inproceedings{milazzo_rouphail_allen_hummer_1997, title={Proposed revisions to Highway Capacity Manual chapter 9: Pedestrian and bicycle analysis procedures}, booktitle={Proceedings of the ASCE Specialty Conference: Traffic Congestion and Safety in the 21st Century, Chicago, IL, June 8-11, 1997}, author={Milazzo, J. and Rouphail, N. and Allen, P. and Hummer, J.}, year={1997} }
 @inbook{dutt_hummer_clark_1997, title={User preferences of flourescent strong yellow-green pedestrian crossing sign}, ISBN={0309061741}, number={1605}, booktitle={Research on traffic control devices}, publisher={Washington, DC: Transportation Research Board}, author={Dutt, N. and Hummer, J. E. and Clark, K. L.}, year={1997}, pages={17–21} }