Freeway Service Patrols Research Articles

Evaluating the impact of Road Rangers in preventing secondary crashes

Many transportation agencies utilize freeway service patrols (FSPs) to quickly identify and respond to incidents. The objectives of FSP are to minimize the incident duration and increase safety at the incident scene. The current research explored the safety benefits of Florida’s FSP program known as Road Rangers – harnessed from lowering the likelihood of secondary crashes (SCs) – compared to other responding agencies. The analysis was done on 6088 incidents that occurred on freeways in Jacksonville, Florida, from 2015 through 2017. Since SCs were not explicitly identified in the SunGuide® incident database, the study adopted a data-driven technique that used BlueToad® speed data to identify them. Once SCs were identified, a model was developed to identify factors influencing their occurrence. Factors such as an increase in equivalent hourly traffic volume, incident impact duration, and the percent of lanes closed significantly increased the likelihood of a SC. Besides, moderate/severe incidents, crash events, weekdays, peak hours, shoulder blockage, and incidents involving towing showed a high likelihood of resulting in a SC. Of practical importance, the model results revealed that a minute increase in incident impact duration increased the SC probability by 1.2 percent, with other factors held constant. Based on a 16-minutes decrease in incident impact duration, the Road Rangers program could lessen the probability of SCs by 21 percent, compared to other agencies. These findings could be beneficial to incident managers, responders, and researchers in evaluating the program’s performance.

Impact of Freeway Service Patrols on Incident Clearance Duration: Case Study of Florida’s Road Rangers

AbstractFlorida’s 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 incide...

Genetic Algorithm for Optimizing Routing Design and Fleet Allocation of Freeway Service Overlapping Patrol

The freeway service patrol problem involves patrol routing design and fleet allocation on freeways that would help transportation agency decision-makers when developing a freeway service patrols program and/or altering existing route coverage and fleet allocation. Based on the actual patrol process, our model presents an overlapping patrol model and addresses patrol routing design and fleet allocation in a single integrated model. The objective is to minimize the overall average incident response time. Two strategies—overlapping patrol and non-overlapping patrol—are compared in our paper. Matrix encoding is applied in the genetic algorithm (GA), and to maintain population diversity and avoid premature convergence, a niche strategy is incorporated into the traditional genetic algorithm. Meanwhile, an elitist strategy is employed to speed up the convergence. Using numerical experiments conducted based on data from the Sioux Falls network, we clearly show that: overlapping patrol strategy is superior to non-overlapping patrol strategy; the GA outperforms the simulated annealing (SA) algorithm; and the computational efficiency can be improved when LINGO software is used to solve the problem of fleet allocation.

Evaluation of the Benefit-to-Cost of Freeway Service Patrol in Advanced Video Surveillance System Environment: A Case Study in China

Abstract With the growing traffic incidents led by the rapid increase of traffic volume on freeways, Chinese government is facing how to ensure the efficiency and safety of the freeway system. One of the hot debates is the efficiency of Freeway service patrols (FSPs) technology in the advanced video surveillance system environment, namely dense video-based surveillance system (DVBSS). To help making a correct decision, this paper develops an effective approach to assess the effectiveness of FSPs in the DVBSS environment. This paper proposes a simulation method to measure the B/C ratios of FSPs in advanced VSS environment. B/C ratios are evaluated under four scenarios namely basic scenario, FSP1, FSP2, and FSP3. All scenarios were simulated in the 9.4-kilometer segment and data were collected from the working log of traffic monitoring center. Among all scenarios, B/C ratio of FSP1 is lowest, sometimes less than1, indicating that not all the FSPs scenarios are effective in the advanced VSS environment. However, the B/C ratios of FSP2 and FSP3 in mean cost scenarios exceed 1, represent as 4.33:1 and 3.47:1 respectively. It indicated that FSPs technology is still an effective way for traffic incident management in VSS environment. To explore the robustness of the results, authors extended the length of patrolling segment to 13.4 kilometers.

Evaluation of the integrated application of intelligent transportation system technologies using stochastic incident generation and resolution modeling

This paper presents the use of the microscopic vehicle traffic simulation software PARAMICS to evaluate different incident management implementation alternatives in South Carolina. This study customized the simulation model for random spatial and temporal traffic incident generation, and modeled different incident alternatives through an application programming interface. This incident management system integrated incident reporting hotlines, traffic cameras, traffic sensors, and freeway service patrols (FSPs), finding that this approach to incident management outperformed the application of traffic cameras or FSPs alone. The integrated application of intelligent transportation system technologies significantly reduced incident duration and total vehicle hours of travel during an incident. In addition, FSP response policy and headway affected the incident management performance.

Operational impacts of incident quick clearance legislation: a simulation analysis

AbstractMany states in the US have enacted quick clearance laws requiring drivers of vehicles involved in minor incidents to move their vehicles from travel lanes prior to the arrival of first responders. Since little is known about the effectiveness of these laws, this research sought to find the benefit–cost ratio of advertising quick clearance legislation to improve driver compliance, and compare it with benefit–cost ratios of other incident management strategies, particularly traffic cameras, freeway service patrols, and traffic sensors. The analysis used traffic simulation that applied application programming interfaces to produce random spatial and temporal occurrence of incidents, including incident start times, durations, and locations, based on normal distributions developed from field data, to test before and after the law scenarios. The results provide decision makers with support for prioritizing funding between these incident management strategies and indicated that investments in the advertisement of this law was beneficial. Copyright © 2011 John Wiley & Sons, Ltd.

Freeway service patrol deployment planning for incident management and congestion mitigation

This paper investigates the problem of deploying freeway service patrols to detect, respond to and clear traffic incidents in two settings, deterministic and stochastic. The deterministic setting assumes that there is only one scenario of incident occurrence and, in the stochastic counterpart, there are many scenarios, each of which occurs with a probability. The main objective of both problems is to minimize the total incident response time. Rather than minimizing the expected total response time, the stochastic model minimizes the expected total response time over the high-consequence scenarios instead. In both settings, the deployment problem can be formulated as a mixed-integer nonlinear optimization problem, a hard class of problem to solve. To obtain solutions in a reasonable amount of time, three heuristic algorithms are proposed. In particular, one makes use of the dual information, another employs a neighborhood search technique and the third uses simulated annealing, a meta-heuristic algorithm. Numerical experiments based on data from Sioux Falls demonstrate that all three algorithms provide solutions with a significant reduction in total response time without using an excessive amount of CPU time.

Harnessing the Power of Microscopic Simulation to Evaluate Freeway Service Patrols

Public agencies have been increasing their use of freeway service patrols (FSPs) to help with incident detection, verification, response, and motorist support. Using the microscopic simulation software PARAMICS, this study evaluated the benefits of FSPs in reducing the duration of roadway blockage, following a crash and the resulting vehicle delay. A customized PARAMICS model was developed for random spatial and temporal crash generation, and the modeling of different number of FSPs and response policies through an application programming interface. Analysis of the simulation results revealed that both response policy and the number of FSPs affected the crash response times and consequently the duration of blockage and vehicle delays. The effects of different response policies diminished as the number of FSPs increased. Benefit-cost analysis indicated that FSP programs can obtain a maximum benefit-cost ratio of 22:1, which decreases as the number of FSPs increases, number of crashes per year decreases, and the discount rate increases.

Evaluation of incident management strategies and technologies using an integrated traffic/incident management simulation

This paper describes Rutgers Incident Management System (RIMS) software that is developed to evaluate the benefits of various incident management strategies and technologies. This tool can generate incidents and test various response strategies and technologies. South Jersey highway network is used as a test network due to the available historical incident data. The evaluated incident management strategies include the deployment of Variable Message Signs (VMS) to divert traffic during incidents and the use of Freeway Service Patrols (FSPs) for detecting and verifying incidents efficiently. The simulation-based evaluations also include the effect of cellular phone users in the network on the incident detection and verification times. The results show that the studied incident management strategies have positive impacts on reducing incident durations while being cost effective. More specifically, the deployment of VMS for diverting traffic in case of an incident results in a benefit cost ratio of 9.2:1; an additional service unit in freeway patrol results in reduced incident detection and verification time with a corresponding benefit-cost ratio of 3.9:1.

A Scenario-based Model for Fleet Allocation of Freeway Service Patrols

As one component of traffic incident management systems, freeway service patrols (FSP) facilitate quick removal of incidents through faster response and reduced clearance time. This paper is to investigate how to strategically allocate tow trucks among patrol beats to optimize the performance of the FSP system. A mixed-integer nonlinear programming model is formulated to minimize the expected loss with respect to a set of high-consequence scenarios of incident occurrence, which may be solved in polynomial time for realistic networks. Moreover, the data required for the model can be easily obtained from practice.

A simulation approach for quantifying the cost-effectiveness of freeway service patrols programs

Freeway Service Patrols is one of the main components of highway Incident Management (IM) programs because of its low-cost feature and effectiveness in incident detection, mitigation and clearance. This paper presents a methodology to quantify freeway service patrol programs' cost-effectiveness with limited operation data using microscopic simulation. Simulation models are developed to test benefits of patrol service by comparing 'with' and 'without' scenarios under various traffic conditions. The analysis results from a case study indicate that patrol operations may have a significant impact on incident detection process, especially for incidents of low severity, such as debris and abandoned vehicles.

Optimal Fleet Allocation of Freeway Service Patrols

As one component of traffic incident management systems, freeway service patrols (FSP) facilitate quick removal of incidents through faster response and reduced clearance time. This paper is to investigate how to allocate tow trucks among patrol beats to maximize the effectiveness of the FSP services. A min–max bi-level programming model is proposed to determine an optimal fleet allocation that minimizes the maximal system travel time that incidents may incur. A heuristic iterative solution algorithm is proposed to solve the model. Both the model and the algorithm are demonstrated and validated through a numerical example.

Tools for Supporting Implementation Decisions of Intelligent Transportation System

Planners and engineers may consider both conventional capacity improvements and intelligent transportation systems (ITS) to address transportation problems. Examples of ITS include freeway service patrols, advanced vehicle location systems, and certain elements of employee transit pass programs, each with various advantages. Details of a system to help planners and engineers make informed decisions about ITS deployment are provided. ITS Decision is designed to provide comprehensive information about state-of-the-art ITS technologies in a relevant form—the user can access desired information without sifting through irrelevant material. In addition, ITS Decision offers innovative tools to help users identify ITS appropriate for particular transportation problems. An expert system queries the user about specific conditions, diagnoses the problem, and suggests ITS remedies. The case-based reasoning tool lets users match historical cases that are most similar and see the effects. Given the still limited penetr...

Tools for Supporting Implementation Decisions of Intelligent Transportation Systems

Planners and engineers may consider both conventional capacity improvements and intelligent transportation systems (ITS) to address transportation problems. Examples of ITS include freeway service patrols, advanced vehicle location systems, and certain elements of employee transit pass programs, each with various advantages. Details of a system to help planners and engineers make informed decisions about ITS deployment are provided. ITS Decision is designed to provide comprehensive information about state-of-the-art ITS technologies in a relevant form—the user can access desired information without sifting through irrelevant material. In addition, ITS Decision offers innovative tools to help users identify ITS appropriate for particular transportation problems. An expert system queries the user about specific conditions, diagnoses the problem, and suggests ITS remedies. The case-based reasoning tool lets users match historical cases that are most similar and see the effects. Given the still limited penetration of ITS into appropriate settings, the expert system and case-based reasoning tools are meant to stimulate greater deployment of promising technologies in localities that have not adopted such systems.

Method for Priority-Ranking and Expanding Freeway Service Patrols

Freeway service patrols (FSPs), classified as part of intelligent transportation systems, are programs that use roving vehicles to patrol congested and high-incident sections of freeways; they help to smooth traffic flow by aiding stranded motorists and assisting in incident clearance. Many major urban areas currently have patrols, and most medium-sized urban areas are following suit. The success of FSPs has resulted in frequent requests for service expansion. However, the decision on where to put the next patrol is becoming more difficult because an assessment of greatest need typically indicates that high-priority areas already have the service, whereas the possible effects of the service are often indistinguishable on lower-priority facilities. A new approach was developed to help determine the most beneficial locations for patrol deployment by using expanded placement criteria. North Carolina was used as a case study. Analysis of three incident and crash indexes was combined with spatial analysis, incident type distributions, average hourly freeway traffic volumes, and incident delay estimations to identify, evaluate, and compare candidate facilities for FSP expansion. Results of the research were incorporated into a decision support tool that allows easy planning and operational assessment of candidate sites by comparing performance values between sites, modeling the effect of FSPs, and estimating their key potential benefits. By using the tool, decision makers can quickly assess the needs of different facilities and make an informed, cost-effective decision on where to implement the next service patrol.

Development of Tennessee’s Freeway Service Patrol (HELP) Program

Many studies have been conducted to describe and evaluate the benefits of freeway service patrols, but much less is known about the planning and institutional development of such programs. This case study describes the implementation of Tennessee’s freeway service patrols. In 1998 the Tennessee Department of Transportation (TDOT) began planning for patrols to operate on the highest-volume freeways in the state’s four largest cities—Chattanooga, Knoxville, Memphis, and Nashville. After a staged implementation plan, TDOT has successfully implemented the patrols, known as HELP, in all four cities while also moving forward with related intelligent transportation system and incident management initiatives. Five aspects of program development are described that have been especially important to the success of the program—teamwork, attention to human resource issues, comprehensive training, first-rate vehicles and equipment, and communications.

ITS Impacts on Safety and Traffic Management: An Investigation of Secondary Crash Causes

Freeway service patrols, an increasingly popular choice in combating the effects of traffic incidents on freeway operations, have been known to reduce incident response and clearance time. This reduction can help alleviate the delay due to non-recurrent, incident related congestion, as well as lower the chance of secondary crashes. While much work has been done in the direction of identifying the benefits stemming from the delay savings by freeway patrols, little has been done to identify the potential savings from lowering the likelihood of secondary crash occurrence. Using a 5-year incident data base from the Borman Expressway, we develop logistic regression models to examine what primary crash characteristics are likely to influence the likelihood of a secondary crash. The findings suggest that clearance time, season, type of vehicle involved, and lateral location of the primary crash significantly influence the likelihood of secondary crash occurrence. Further, the 1995 potential benefit from secondary crash reduction was $568,080 exceeding the 1995 Hoosier Helper freeway service patrol program costs by a factor of 1.38. Given a better understanding of what contributes to secondary crash occurrence, various components of incident management can be operated at a higher level of cost-effectiveness.

Freeway Service Patrols: A State of the Practice

Freeway service patrols have been cited as one of the most effective elements of an incident management program for reducing incident detection time and incident duration. Service patrol programs utilize roving vehicles to patrol congested and high incident sections of urban freeways. The state of the practice of freeway service patrol programs in the United States is documented in this paper. A telephone survey was conducted with managers of 53 freeway service patrols in 22 states. Approximately 74 percent of the surveyed service patrols are sponsored exclusively by public agencies. Approximately 47 percent of the surveyed patrols are sponsored exclusively by Department of Transportations; 6 percent are sponsored exclusively by police agencies; and 21 percent are sponsored by multiple public agencies. Approximately 34 percent of the patrols receive federal support funding. Finally, 27 percent of the patrols operate with private funding sources. Service patrol hours of operation vary from program to program, with the most common being coverage of the weekday a.m. and p.m. peak periods. Approximately 70 percent of the surveyed agencies own and operate their own vehicles, whereas 26 percent contract with private tow companies to provide drivers and vehicles. Benefits associated with service patrols are typically quantified by multiplying a value of time by the estimated delay reduction provided by the service patrol in vehicle-hours. Available benefit to cost analyses for 15 of the service patrols studied ranged from 2:1 to 36.2:1. A contact list and recommendations for agencies interested in starting a new service patrol program are also included in this paper.

New Model for Predicting Freeway Incidents and Incident Delays

This paper presents a new model that predicts the number of freeway incidents and associated delays based on general freeway segment characteristics, traffic volumes, and incident management procedures. The model is intended to be used in planning capacity-enhancing freeway improvements and incident management programs. Estimates of incident frequencies, severity, durations, and delays are provided for seven standard incident types, each of which represents a significant fraction of total unplanned incidents and has severity and/or duration characteristics substantially different from the others. In addition to describing the incident prediction model, the paper addresses the need for a coordinated national strategy for collecting incident data, with particular attention to urban freeways. It concludes that the incident data systems that have evolved in several urban areas, often in connection with freeway service patrols and incident response team activities, already provide a valuable nationwide data resource for understanding incident patterns and their variations. However, better national coordination of locally collected incident data would be helpful for addressing issues beyond the scope of the local concerns for which virtually all current systems were originally designed. Specific areas for improvement include the definitions of incident types, descriptions of incident locations (relative to both the length and breadth of the highway), and data recording the critical times during incidents such as when detection, response, and clearing occur. Language: en

I-880 Field Experiment: Analysis of Incident Data

The I-880 field experiment has produced one of the largest data bases on incidents and freeway traffic-flow characteristics ever compiled. Field data on incidents were collected through observations of probe-vehicle drivers before and after the implementation of freeway service patrols (FSPs) over a freeway section. Supplementary information was collected from the California Highway Patrol’s computer-aided dispatch system, FSPs, and tow-truck company logs. The incident patterns are described and the major factors affecting incident frequency and duration are identified. FSPs significantly reduced the response times but did not have a significant effect on the duration of all incidents.