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21st Century Operations Using 21st Century Technologies

CHAPTER 1. INTRODUCTION

Background

Safety Service Patrols (SSP) have existed in one form or another since the early 1960s, and have served as a vital part of Traffic Incident Management (TIM) programs. SSPs are also referred to as Freeway Service Patrols (FSP), Courtesy Patrols, Emergency Response Units, and Motorist Assistance Patrols (MAP). The Federal Highway Administration (FHWA) has promoted TIM program implementation, including SSP and traffic management centers (TMC), in the interest of promoting safety and mobility throughout the United States. The FHWA has provided both technical and financial assistance to many States developing and deploying TIM programs. The safety of incident victims and responders has been of paramount concern, along with the rapid detection and clearance of these incidents.

In the 1990s, FHWA created a multi-agency approach to training incident responders in the form of a two-day workshop as part of Demonstration Project 86[1]. Some of the primary topics of these workshops included SSP, quick clearance, and inter-agency coordination and cooperation. Today, FHWA continues to evolve and promote the use of the SSP along with quick clearance and inter-agency coordination and training. The emphasis is not only on detecting and clearing incidents but also on guiding motorists approaching an incident scene safely past or around the impacted travel lanes. The value of these programs has been reflected in various benefit-cost studies that have been carried out by SSP operators.

Today's SSP deployments may vary in the types of service provided, vehicles used, and staffing. Services may range from a "courtesy patrol" providing simple motorist assistance, to higher-level services providing aggressive roadway clearance of disabled and wrecked vehicles, including removal of large trucks. The operations and maintenance of these SSP services differ from region to region. Some of the simpler operations may be operated by the private sector as "Samaritan patrols" through public-private partnerships, while more complex operations may be operated by a State department of transportation, police agency, transportation authority, or some partnership of the above. Many services maintain all their assets (e.g., trucks, heavy equipment, garages, etc.) in-house, while others may contract the staffing, procurement and/or management of assets such as trucks, garages and heavy equipment.

Patrols can be staffed in several ways including dedicated agency employees, contracted services, or agency personnel assigned to different duties in their routine positions but can be applied on an as-needed or overtime basis.

Service Patrols: A Key to Effective Traffic Incident Management

SSPs are considered an integral TIM component, and they also complement the efforts of regional TMCs in detecting, confirming and eventually clearing incidents that cause lane blockages. From a public perspective, they serve as the front-line representative of the agency who operates the patrols, providing face-to-face contact when an individual traveler may most need assistance.

SSP duties in TIM may include:

  • Provide the initial report, response or verification of an event.
  • Provide initial traffic control and scene safety for responders and victims.
  • Support the incident commander as needed to manage the lane closure and protect the incident site, victims, and agency personnel.
  • Communicate resources needed to their agency.
  • Assist in the quick clearance of debris, disabled vehicles, or crashes in or along the travel portion of the roadway.

The FHWA Service Patrol Handbook states, "Communications with the TMC, both directly or through the service patrol at the incident, can only improve responses and advance the treatment and transport of the injured. When service patrols arrive on the incident scene before fire and rescue personnel, they can relay valuable information such as the nature and severity of injuries, and the number and age of any victims."[2] This statement reinforces the need for clear communication between the TMC and the patrollers in the SSP vehicles. Both the TMC operator and the patroller should understand each other's specific job functions and needs. An SSP can greatly contribute to quick incident clearance through reliable information exchanges with the TMC. These actions can reduce the resulting delays to motorists as well as the likelihood of secondary incidents occurring upstream of the original incident.

Service patrollers are often the first agency representatives on an incident scene. The patroller's role in the incident command environment will depend on regional policies and the designated level of responsibility of the SSP when compared with police or other first responders. They may be responsible for communicating particular incident details to the TMC, although other entities such as police or fire departments may typically serve as the actual incident commander. Key relationships for a successful SSP (both patrollers and dispatchers) include those with the first responders and law enforcement agencies, TMC operations staff, other transportation agency staff responsible for incident clearance or clean-up activities, and towing companies.

Examples of Why Some Agencies Implemented Service Patrols

It is helpful to understand the reasons why existing SSP programs were founded when contemplating the establishment of a service patrol program or evaluating options to update an existing program. The primary purpose of SSP is to maximize the safety and mobility of the transportation network. SSP accomplishes this purpose through rapid removal of incidents from travel lanes or shoulders, which reduces traffic flow disruption that might result in secondary incidents.

From their initial success and corresponding program results, including favorable motorist feedback, many SSP programs have evolved into much larger programs. Some expand from a focus on specific roadway segments and peak time periods into regional coverage over a longer period (sometimes 24 hours per day/7 days per week) of coverage depending on the resources and funding available from the public agencies, as well as public and/or private partners.

Although the purpose of SSP may be clear, the impetus for such programs may differ depending on the region. Examples include:

  • Seasonal programs developed to reduce travel delays to vacation destinations while monitoring conditions along the key access routes.
  • Construction traffic mitigation programs employing SSP to monitor delays and keep work zones clear of crashes and breakdowns.
  • Programs focused on the mitigation of non-recurring congestion in order to enhance roadway safety and operations.
  • Weather-related programs started as a result of extreme weather conditions.

Each of these examples may evolve into more extensive programs covering larger networks over longer periods of the day or week, depending on the effectiveness of current services and demonstrated needs based on current and projected traffic conditions.

Seasonal Program Example - Maryland's Coordinated Highways Action Response Team Program

The roots of Maryland's Coordinated Highways Action Response Team (CHART) Program are derived from a patrol created in the early 1980s focused on improving seasonal traffic flow to and from Maryland's Eastern Shore during the summer months. The patrol focused on the routes connecting Baltimore and Washington to the Chesapeake Bay Bridge along with major routes on the Eastern Shore. In addition to delays on the Bay Bridge, there were other delays along US-50 across the Eastern Shore area, including several at-grade intersections as well as a frequently-operated drawbridge. Issues with disabled vehicles and crashes along this corridor further impacted traffic operations.

In order to mitigate these delays and associated incidents, the Maryland State Highway Administration (MdSHA), in coordination with the Maryland State Police (MSP), implemented a program known as Eastern Shore Traffic Operations (ESTO) that consisted of staff from various MdSHA offices equipped with light trucks. Staff patrolled the main corridors and assisted stranded motorists, removed minor crashes from the travel portion of the roadway, and manually controlled traffic signals at major intersections when needed. The program proved to be a success and was so well received by the public that Governor William Donald Schaffer announced in 1987 a new program called "Reach the Beach." This program included expansion of the MdSHA Emergency Patrols as well as a Traffic Operations Center (TOC) to provide motorists with real-time updates on travel conditions.

In 1989, a serious crash along I-270 northwest of Washington, DC resulted in a very long closure of the interstate. In response, the program was expanded to include a new TOC in the Washington, DC region. The CHART Program evolved into a statewide traffic management program operating 24 hours per day with a Statewide Operations Center (SOC).

Construction and Work Zone Program Examples – Florida and Nevada

In the late 1980s, District 4 of the Florida Department of Transportation (FDOT) started a patrol service focused on assisting stranded motorists within construction zones. The first deployment of this service was for the I-95 expansion in Broward County, and was implemented by the construction contractor at the direction of FDOT. The patrols assisted stranded motorists with basic services, such as furnishing a limited amount of fuel, assisting with tire changes, and helping with other types of minor vehicle repairs. In February 1995, the FDOT District 4 Office initiated the program in its current form that initially covered the entire I-95 corridor through Broward County. This effort proved to be so successful that it was expanded to Palm Beach County in 1997 and has since been expanded to include all types of roadway incidents, using heavier patrol vehicles with tow capabilities. In December 1999, FDOT began funding the service patrol program on a statewide level, realizing that it was one of the most effective elements of FDOT's Incident Management program. The service patrol program received the name "Road Rangers" as a result of a statewide contest held in 2000. The program remains a highly successful FDOT service. There were almost 4.4 million assists recorded between 2000 and 2013.

Table 1 shows the annual number of assists provided by the Service Patrol since 2000.

Table 1. Florida Service Patrol Assists (2000-2013).

Year

Assists

2000

112,000

2001

198,372

2002

279,525

2003

316,883

2004

342,895

2005

336,684

2006

267,358

2007

383,584

2008

320,217

2009

296,041

2010

351,941

2011

395,516

2012

399,008

2013

374,971

The Nevada Department of Transportation's (NDOT) FSP program started in 1998 in a manner very similar to that of Florida. The NDOT FSP program primarily used vans and had a focus on motorist assistance. The program began on a trial basis in Las Vegas to mitigate traffic congestion caused by the US 95 roadway construction project. The program was operated within the construction limits. From there the program slowly grew to include the Las Vegas and Reno/Sparks metropolitan areas. Today, the NDOT FSP program continues in those regions with corporate sponsorship supporting the operational costs of these services. In addition, NDOT also provides Incident Response Vehicles (IRV) in the Las Vegas area, which assist in the removal of incidents from travel lanes. The purpose of the NDOT FSP program is to improve safety on heavily traveled urban freeways by reducing the time required to remove incidents that disrupt traffic flows and cause traffic congestion during peak travel periods.

Examples of Programs Focused on Mitigation of Issues Related to Non-Recurring Congestion and Safety – Pennsylvania and Colorado

When Pennsylvania Department of Transportation (PennDOT) District 8-0 in the Harrisburg area began operating a TMC, the operations staff noted from congestion studies on their roadway network that even disabled vehicles on the shoulders were causing delays. In order to realize better system operations, crashes and other obstructions needed to be cleared from the roadway quickly and more efficiently, whether in travel lanes or on the shoulder. District 8-0 staff decided to follow the guidance of an FHWA research study that identified service patrols as a good tool to provide incident management services to the district's interstate network. The PennDOT District 8-0 office implemented two service patrol trucks on a trial basis that proved to be successful in clearing incidents and reducing related congestion. PennDOT has since expanded the operation to three trucks patrolling the Harrisburg area during peak travel times. Since the program's inception, PennDOT and the motoring public have realized fewer secondary crashes, reduced detection times of incidents and disabled vehicles, and a reduction in the amount of time abandoned vehicles sit on highway shoulders during the hours that the patrols operate.

In 1993, PennDOT District 6-0, located in the Philadelphia region, began operating the region's first TMC. PennDOT soon realized that they needed to clear crashes more quickly to lessen the impact of freeway congestion in Philadelphia. They worked with the Philadelphia Police Department who managed the traffic along I-95 at the time. The sponsored Samaritania program was contracted to patrol the roadways and offer assistance to stranded motorists as well as acting as the "eyes and ears" of the District 6-0 TMC. In July 2000, Samaritania ceased operations in Philadelphia, but PennDOT began contracting services to operate the service patrol program on a permanent basis since the need for these patrols was so great. The program started with three patrol trucks and it has grown to 13 patrol vehicles. The program operating area has expanded to include suburban Philadelphia as well as the city. The patrollers operate in the city of Philadelphia five days a week, from 5:00 AM until 7:30 PM (15 hours). In the suburbs, they work five days a week during peak hours (8 hours per weekday).

The Colorado Department of Transportation (CDOT) has had courtesy patrol operations in place for more than 25 years. CDOT's original purpose for the program was to enhance safety and operations along Colorado interstates. The program was funded using grant money for the initial two to three years of operations, and then the program was transferred to CDOT for financial support. Initially, the program provided only motorist assistance, but it has evolved to include quick clearance in recent years. Colorado currently has three active service patrols. The first is called the Mile High Courtesy Patrol (MHCP) that patrols the Denver Metro area. The Mountain Courtesy Patrol (MCP) and a Heavy Tow program along I-70 west of Denver, were added. The Heavy Tow program provides services on heavy traffic weekends to assist with spinouts, crashes, and tractor-trailers that are disabled on mountain grades.

Weather-Related Program Example - Colorado

Due to the severe weather conditions during the winter months, CDOT and the Colorado Motor Carrier Association developed a variant of an SSP service known as the Heavy Tow Program along the I-70 corridor between Denver and Vail. Under the program, heavy tow units are staged at strategic locations along the I-70 corridor during high traffic conditions or when storms are anticipated. When a Class 8 or commercial vehicle becomes disabled, the heavy tow unit in the area responds and removes the vehicle to a safe haven at no cost to the trucking fleet. At that point, the trucking company is responsible for moving the vehicle. The program started in 2008 and was found to be successful in reducing the clearance time of large trucks stuck in the snow blocking roadway lanes. The lane clearance times were cut in half from previous seasons to an average of 27 minutes. The economic benefit is reported by CDOT at over a 20:1 return on investment on a program that the State estimates to cost $500,000 to fund per year.[3]

Example of Evolution from Earlier Programs – Pennsylvania Turnpike

The Pennsylvania Turnpike Commission evolved its SSP activity from an earlier approach that originally stationed ambulances at each maintenance shed location. The vehicles were on-call 24 hours per day to provide a quick response to incidents where there were injuries involved. During the early to mid-1990s, the Turnpike contracted with local fire departments to respond to medical assistance calls on the Turnpike facility the ambulances were replaced by patrol vehicles for emergency response to incidents. One patrol vehicle was stationed at each maintenance shed staffed by maintenance utility workers. These vehicles currently patrol their routes twice per shift and are available at the maintenance facilities for immediate response to any event that occurs when they are not actively patrolling. The patrol staff are assigned other duties when not executing patrol duties.

Service Patrol Goals and Objectives

Service patrol goals and objectives vary from program to program depending on the agency's mission. In general, SSP programs are intended to:

  • Reduce non-recurring traffic congestion and improve travel time reliability by quickly and safely removing debris, disabled vehicles, and minor crashes from the travel portion of the roadway. It is important to note that removing disabled vehicles and abandoned vehicles from the shoulders of the roadway lessens congestion impacts and improves safety for motorists and the occupants of disabled vehicles along the shoulders.
  • Improve highway safety for responders and motorists by providing proper traffic control to support a safe incident work area for responders and victims. The SSP guides traffic safely through or around the affected section of roadway and assists stranded motorists.
  • Provide timely and accurate information to the TMC allowing staff to activate traveler information devices (e.g., dynamic message signs (DMS), highway advisory radio) to warn motorists when they are approaching an incident or closure, or systems (511, websites, media, etc.) to alert motorists of the current road conditions, lane or road closures, diversions, and any delays prior to their departure.

When implementing or expanding an existing patrol program, the goals and objectives need to be carefully defined to address the needs of motorists and the agency. Once the goals and objectives have been set, it is very important to capture as much data as possible to track the performance of the program and determine if the goals and objectives are being attained. FHWA, through a focus group initiative[4], has identified three TIM-specific objectives and associated performance metrics. The three objectives include:

  • Reduce roadway clearance time - the time between the first recordable awareness of the incident by a responsible agency and the first confirmation that all lanes are available for traffic flow.
  • Reduce incident clearance time - the time between the first recordable awareness of the incident by a responsible agency and the time that the last responder has left the scene.
  • Reduce the number of secondary incidents - the number of crashes that occur after the time of the primary crash, either within the original incident scene or within the queue in either direction that is caused by the original incident.

While it is still difficult to accurately measure some of these objectives uniformly from program to program, more information is now available thanks to the availability of Global Positioning System (GPS)-based dispatch data as well as real-time traffic data. For the majority of incidents, the first notification of the event is received by a 911 call center or other public safety answering point (PSAP). As TMCs begin to integrate or receive a cleansed data feed from 911 call centers and other PSAP's Computer Aided Dispatch (CAD) systems, the first recordable awareness data is now available to accurately reflect the response and clearance times of incidents. Numbers and types of incidents are logged. Assists or actions taken by the patroller to clear the motorist and/or vehicle from the roadway are also logged.

It is typically a greater challenge to relate secondary incident data to an original incident because criteria needs to be defined to relate potential secondary incidents to primary incidents. The criteria which involves the association of the time and location of each incident should be defined so that TMC operators and SSP dispatchers can confirm the relationship between particular primary and secondary incidents. This is especially important to capture for later data retrieval and performance measures analysis.

Benefits of Implementing or Enhancing an Existing Service Patrol Program

An agency can realize many benefits as a result of implementing a service patrol program that meets the needs of the agency and the communities that it serves. As with any sustainable program, the need for the service must be clearly defined whether it will be a new service, an expansion of an existing service operating area, operating hours, or an increase in the number of patrols. The benefits must be clearly identified for the agency as well as the community and motoring public. Measurement of the benefits from the resulting service implementation is critical to justifying the new or expanded service as well as for managing and maintaining service performance and success.

Typical Measures

The FHWA's TIM Benefit-Cost (TIM-BC) tool[5] provides a standardized approach, using a series of simulation tools, to establishing the potential effectiveness of SSP services given capital and operating costs. Agencies such as New York State Department of Transportation, FDOT, and others have demonstrated direct means of measuring benefits and costs.

Data collection is an ongoing process. If possible, a before and after data comparison should be compiled to quickly identify and illustrate the added benefits of an SSP program deployment. Typical measures for determining the benefits established by SSP deployments include:

  • Safer environment for first responders and motorists measured by reduction in staff injuries in the vicinity of the initial incident location.
  • Reduction in incident duration measured by decreased detection, response, and clearance times.
  • Reduction of secondary incidents.
  • Reduction in vehicle delays and environmental-related factors such as emissions and fuel consumption.
  • Timeliness of verification and real-time updates on traffic conditions that enable more accurate traveler information about freeway conditions and estimated durations.

Fundamental Benefits and Core Services

Several service patrol benefits depend on the level of SSP deployment and their assigned missions. Some of the "fundamental benefits and core services cited" according to the FHWA's "Service Patrol Handbook"[6] include:

  • Reduced incident duration.
  • Quicker debris removal.
  • Assistance to stranded motorists and crash victims.
  • Traffic control and management.
  • Real-time updates on traffic conditions (more accurate traveler information).

Secondary benefits can be gained from the direct services that patrols provide. These include:

  • Improved traffic flow as a result of reduced incident duration and better traffic control.
  • Reduced travel time, fuel costs, and vehicle emissions.
  • Improved travel time reliability.
  • Improved motorist and TIM responder safety.
  • Reduced number of lanes closed for an incident.
  • Reduced secondary crashes.
  • Reduced TIM responder personnel and resources required for incidents when service patrols can handle response (e.g., stalled vehicle).
  • Reduced traffic congestion.

Basic Service Capabilities

SSP implementations provide extensive ranges of services which extend to heavy-vehicle clean-up and incident coordination activities. The typical services offered by service patrols include[7]:

  • Moving disabled or abandoned vehicles from the travel portion or unsafe location along the roadway.
  • Providing fuel.
  • Providing water to person(s) being assisted or for overheated vehicles.
  • Changing flat tires.
  • Providing mechanical assistance such as jump starts, minor mechanical repairs, tire inflation.
  • Assisting stranded motorists with cell phone service or a safe place to wait if vehicle is disabled.
  • Removing obstacles and objects from the roadway to include debris and other hazards.
  • Cleaning up minor vehicle fluid spills.
  • Arranging for towing by calling for the motorist.
  • Providing relocation services to point of safety.
  • Sharing information.
  • Acting as the agency's representative in the Incident Command structure.
  • Requesting emergency services.
  • Providing information and updates to the TMC.
  • Assisting other responding agencies such as law enforcement, fire and rescue, Emergency Medical Services, and other response agencies as needed.

Benefit Case Studies and Evaluations – Some Examples

In order to advance the benefits and levels of service provided by SSP, agencies seeking to approve new programs as well as program expansions may compile performance measure data on existing services and the resultant benefits. There are many examples of how agencies have used data to show the success of SSP deployments and demonstrated benefits through studies or pilot programs.

Justification of 24 Hours per Day/7 Days per Week Services for Maryland Coordinated Highways Action Response Team Patrols

The Maryland CHART Program recognized a need to move their patrols from a Monday through Friday, 16-hours-per-day (nights and weekends were on-call) to a 24 hours per day/7 days per week operation as a result of a SSP Pilot project. MdSHA undertook a two-pronged approach using pilot deployments to determine if the need for their patrol services and associated cost was warranted.

One pilot looked at the need for expansion of SSP services to weekends which, prior to May 2012, was only provided for sporting and other special events on an overtime basis. As part of the pilot, MdSHA scheduled Emergency Patrols on two weekends in June 2012, with two sets of patrollers scheduled for three regions (Baltimore, Frederick and National Capital) on two shifts (5:00 AM-1:00 PM and 1:00 PM-9:00 PM on Saturday and Sunday). All communications were handled from the Statewide Operations Center (SOC) rather than regional TOC facilities. Overall the Maryland CHART Program patrols assisted 202 motorists and managed 75 incidents during the four piloted weekend days. Assists and incidents were equally distributed between morning and evening shifts. The results indicated there was value in considering the expansion of the CHART Program patrol operations to include weekend days, although it would likely require overtime costs for staff.

The second pilot was conducted in November 2012 and examined the expansion of the Maryland CHART Program patrol services to weeknight periods. The pilot deployed two Emergency Response Technicians (ERTs) in two trucks, patrolling the beltways around Baltimore and the National Capital Region on weeknights from 9:00 PM to 5:00 AM between Sunday night and Friday morning. They responded to road closure incidents in other areas of the State as well. The eight-week operation was interrupted for two days due to a weather event, Hurricane Sandy, and the MdSHA's preparation and response to the storm and its aftermath. Over the eight weeks of the pilot, the two ERTs assisted 164 motorists and managed 150 incidents. The Wednesday-into-Thursday shifts proved to be the highest day for assists with 47, while Thursday-into-Friday shifts saw the greatest number of incidents with 40. Nearly a quarter of all incidents during the pilot involved lane closures of greater than 50% of the roadway, and a third of those incidents involved closures of the entire roadway. All closures were resolved prior to the start of the normal day shift. The effort of night patrols in managing these closures had a significantly positive impact on the morning rush hour.

The pilot programs provided documentation of the potential benefit of expanding the hours of the service patrol. This information provided justification for the legislature to give MdSHA an additional 24 permanent State positions in order to implement patrols on a 24 hours per day/7 days per week basis. The regional TOCs maintained normal weekday operating hours and the SOC, which was already operating 24 hours per day/7 days per week, maintained all of the communications for overnight and weekend shifts throughout the State.

Demonstrating Benefits and Return on Investment in Hampton Roads, Virginia

A Return on Investment (ROI) study of the SSP in Hampton Roads[8], conducted by the Virginia Transportation Research Council and published in 2007, showed the benefits of service patrols in another context. The Virginia Department of Transportation (VDOT) Hampton Roads SSP program serves approximately 80 miles of roadway on a 24 hours per day/7 days per week basis. It patrols eight routes continuously and provides dispatch service along two other routes. The Hampton Roads region experiences heavy tourist and vacation traffic during the summer months, especially during weekends.

To perform the study, an analysis of route geometrics, traffic characteristics, and incident data was conducted in the Hampton Roads area from July 1, 2005, through June 30, 2006. This data was used to define parameters and inputs into an SSP evaluation model to obtain the benefits of the program. Reviews were conducted on a seasonal basis to assess the fluctuations in cost and benefit during different times of year.

The research found that the total annual benefits of the Hampton Roads SSP, in terms of delay and fuel consumption, were approximately $11.1 million. The costs associated with patrolling the routes in the region were approximately $2.4 million; thus the savings generated by this program were nearly five times the expenditures to fund the program.

The Hampton Roads SSP study compared the average incident duration for crashes, breakdowns and debris along routes that were patrolled routinely by the SSP to similar incidents and conditions without SSP assistance. The study analyzed 33,877 incidents. The study compared the "begin" and "end" times of incidents that had occurred on SSP routes to the times for incidents without SSP assistance that matched in terms of incident type, roadway, and traffic conditions. Incidents on non-SSP roadways only received assistance from the Virginia State Police (VSP).

The analysis performed as part of the ROI comparison not only showed the monetary benefits of the service patrol program, but the benefits of quicker clearance that the patrols provided at incident scenes compared to incidents that were handled solely by the VSP without the SSP services. Some of the findings included:

  • SSP assistance at incidents yielded a 70.7% reduction in duration compared to VSP-only assisted incidents.
  • The mean clearance time for all incidents with SSP assistance, including debris, crashes, and breakdowns, was 10.17 minutes.
  • The mean clearance time for incidents handled only by VSP was 34.70 minutes.

The research identified other associated benefits, such as freeing State police for law enforcement and reducing the time for emergency service providers to clear the scene of an incident.

[1] "Summary of Experiences Related to Demonstration Project 86 – Relieving Traffic Congestion Through Incident Management", USDOT, 1997. [Return to note]

[2] "Federal Highway Administration Service Patrol Handbook", USDOT, 2008, https://ops.fhwa.dot.gov/publications/fhwahop08031/index.htm[Return to note]

[3] "Evaluation of the Heavy Tow Quick Clearance Program", Colorado DOT, 2008, http://aii.transportation.org/Documents/TRSP/TRSP-Other-CDOT-program-evaluation-2008.pdf [Return to note]

[4] "Federal Highway Administration Focus States Initiative: Traffic Incident Management Performance Measures Final Report", FHWA, 2009, https://ops.fhwa.dot.gov/publications/fhwahop10010/fhwahop10010.pdf [Return to note]

[5] FHWA Traffic Incident Management Benefit-Cost (TIM-BC) Tool, https://www.fhwa.dot.gov/software/research/operations/timbc/ [Return to note]

[6] FHWA Service Patrol Handbook, p.8 [Return to note]

[7] Ibid., p.11 [Return to note]

[8] "A Return on Investment Study of the Hampton Roads Safety Service Patrol Program," VTRC 07-RD33, Virginia Transportation Research Council, June 2007, http://www.virginiadot.org/vtrc/main/online_reports/pdf/07-r33.pdf [Return to note]

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