Evaluating Mobility and Safety Benefits of Freeway Service Patrols: A Case Study of Florida\u27s Road Rangers

The Florida’s Road Rangers monitor the freeways for incidents to minimize their adverse impacts on traffic. The objectives of this study were to evaluate the extent to which Road Rangers reduce incident clearance duration (ICD), incident-induced traffic delays (IITDs) and secondary crashes (SCs). Since ICD distributions are often right-skewed, the study applied quantile regression to relate ICD to influencing factors. Data skewed to the right is usually a result of lower bounds in a data set being extremely low relative to the rest of the data. Data from 28,000 incidents that occurred on freeways in Jacksonville, Florida were analyzed. Of the factors analyzed, crash events, incident severity, shoulder blockage, peak hours, weekends, nighttime, number of responding agencies, and towing were found to associate with significantly longer ICDs. Road Rangers were found to reduce incident clearance duration by 25.3%. In other words, shorter incident clearance durations were observed when Road Rangers responded to incidents compared to other agencies. On the second objective, IITDs were estimated by establishing incident-free recurrent travel time profiles as bases from which the incident-induced delays could be measured. To determine the extent to which Florida’s Road Rangers can reduce IITDs, the analysis was based on the data from 4,045 incidents that occurred on freeways in Jacksonville, Florida. The parametric accelerated failure time (AFT) survival model, with Weibull distribution of IITD was used to model IITDs. The results show that significant variables affecting IITDs include incident characteristics (severity, type, towing requirements, lane and shoulder blockage, etc.), Road Rangers involvement, and prevailing traffic conditions. The findings also revealed no significant effects of median width, average detector occupancy and the day-of-the-week on IITDs. A significant and unique contribution of this paper is that the Road Rangers program was found to shorten IITDs relative to other responding agencies by 12.6%. To identify the potential impact of Road Rangers in lowering the likelihood of SCs, this study sought to evaluate the safety performance of the Road Rangers program. Since SCs are often rare, the study applied a complimentary log-log model. The analysis was based on incident data related to 6,088 incidents on freeways in Jacksonville, Florida. Of the factors analyzed, traffic volume, incident impact duration, moderate/severe crashes, weekdays, peak periods, percentage of lane closure, and shoulder blockage were found to significantly increase the likelihood of SCs. While vehicle speed and lighting condition showed little contribution (not significant at 95%) to SC likelihood, Road Rangers were associated with relatively lower probabilities of SC occurrence. Based on the reduction in the average incident duration, the results suggest that the Road Rangers reduce SC risk by 20.9%. Based on increased safety at incident scenes, Road Rangers reduce SC probability by 17.9%. The results of this study can, in general, provide researchers and practitioners with an effective way for evaluating mobility and safety benefits of the Road Rangers program. The developed approaches provide practical guidance on how to quantify the mobility and safety impact of the Road Rangers program. The results can, in general, help practitioners to improve incident management plans

Performance Evaluation of Connected Vehicle (CV) and Transportation Systems Management and Operations (TSM&O) Projects in Florida

BDV29-977-64Connected vehicle (CV) technologies and Transportation Systems Management and Operations (TSM&O) strategies are increasingly being considered by transportation agencies to improve the safety and mobility of the transportation network. To fully understand the potential benefits of CV and TSM&O initiatives, it is crucial to not only identify the performance measures used to evaluate the progress of each initiative, but also to estimate the benefit-to-cost (B/C) ratios to justify the funding requests associated with implementing these technologies and strategies. The primary goal of this research was to assist the Florida Department of Transportation (FDOT) in developing approaches to evaluate the performance of CV projects and current TSM&O strategies being deployed, including the Rapid Incident Scene Clearance (RISC) program, the Road Ranger Service Patrol (RRSP) program, and the Smart Work Zone (SWZ) TSM&O strategies. A comprehensive review of the existing body of literature was conducted to identify the quantitative and qualitative performance measures and metrics that are being considered in evaluating the performance of CV deployments and TSM&O strategies. B/C analyses were conducted to quantify the mobility and safety benefits associated with implementing the RISC and RRSP programs. Results indicate that for every dollar spent on the RISC program, $5.78 is returned in secondary crash savings, and$1.20 is returned in incident-related traffic delay savings. For every dollar spent on the RRSP program, $5.15 is returned in secondary crash savings, and$7.44 is returned in incident-related traffic delay savings. The study also discussed the potential safety and mobility benefits of Smart Work Zone (SWZ) technologies. Performance criteria and evaluation metrics were also developed for the different stages of the CV project development process (i.e., pre-project phase, planning phase, design-deploy-test phase, and the operations & maintenance phase). The performance criteria of two CV deployments in Florida (Gainesville Signal Phase and Timing (SPaT) Project and I-4 Florida\u2019s Regional Advanced Mobility Elements (I-4 FRAME) Project) were also reviewed. Findings from this research offer guidance in evaluating the effectiveness of CV and TSM&O initiatives. Evaluation criteria and approaches presented in this report can better prepare FDOT for deployments

Impact of Freeway Service Patrols on Incident Clearance Duration: Case Study of Florida\u27s Road Rangers

Florida\u27s Road Rangers monitor the freeways for incidents to minimize incident clearance duration. The objective of this study was to evaluate the extent to which Road Rangers reduce incident clearance duration. Because incident clearance duration distributions are often right-skewed, the study applied quantile regression to relate incident clearance duration to influencing factors. Data skewed to the right are usually a result of lower bounds in a data set being extremely low relative to the rest of the data. Data from 28,000 incidents that occurred on freeways in Jacksonville, Florida, for the years 2014-2017 were analyzed. Of the factors analyzed, crash events, incident severity, shoulder blockage, weekends, nighttime, number of responding agencies, and towing were found to significantly increase incident clearance durations. Road Rangers were found to reduce incident clearance duration by 25.3%. In other words, shorter incident clearance durations were observed when Road Rangers responded to incidents compared to other agencies. The results of this study can, in general, provide researchers and practitioners with an effective way of evaluating the mobility benefits of the Road Ranger program