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Benefit-To-Cost Analysis for Safety Service Patrols

By Suzannah Cockerille

The key benefits of employing Safety Service Patrols (SSP) are reductions in the number and duration of travel delays and reduction in fuel consumption, secondary incidents, and environmentally damaging emissions. However, there’s a growing need to quantify and analyze these benefits in order to compare their efficacy with their capital, administrative and operational costs. With an ever-increasing focus on the effectiveness and expense of all aspects of traffic incident management, new methodologies and new tools are being used to assess the value of Safety Service Patrols.

“Quantifying the return-on-investment of Safety Service Patrols can be challenging – there are a number of benefits which are difficult to monetize,” explains Rebecca M. Brewster, President and Chief Operating Officer of the American Transportation Research Institute (ATRI), a leading innovator in transportation-related research and analysis based in Arlington, Virginia. “For instance, calculating the value of time saved [and/or alternative services rendered] by law enforcement officers who do not have to respond to certain minor incidents because there is a Safety Service Patrol in place” is extremely difficult.

As a way to address the many difficulties quantifying the benefit-to-cost ratio of Safety Service Patrols, researchers have created methodologies that define consistent parameters used to measure, as accurately as possible, the usefulness and cost-effectiveness of SSPs. Methodologies vary and are often met with new obstacles, such as capturing real-time data and a need to adapt to incorporate new data sources from a state.

In Benefit Cost Analysis of Freeway Service Patrol Programs: Methodology and Case Study published in January 2009, Jason (Chih-Sheng) Chou and Dr. Elise Miller-Hooks find that ideally a “before-and-after study” would be conducted to properly evaluate the benefit and costs of a patrol, but the reality is that “in most locations, the necessary data to establish a ‘before’ benchmark is not available.” As a result, studies of Safety Service Patrol programs, such as several which have been conducted in Minnesota, Florida, Maryland, Georgia, and northern Virginia, are instead composed of comparisons between responses to incidents with and without the involvement of SSP vehicles to determine savings in fuel consumption and pollution.

The NYSDOT HELP Patrol was a subject of one benefit-to-cost study.

Chou and Miller-Hooks’ study elaborates on simulation-based methodology used to study New York State’s Highway Emergency Local Patrol (HELP) program. The study builds on two simulation platforms: the corridor simulation (CORSIM) platform, a standard simulation platform in the transportation industry, and the Quadstone Paramics[1] simulation platform, to create a microscopic simulation-based methodology using the statistical analyses from nearly 10,000 replicated incidents in a defined metropolitan area in New York over a six-month period. Microscopic simulation-based methods apply car-following and lane-changing behavior models to replicate traffic operation of individual vehicles in a network approximating actual conditions where real-time data is not available. Taking into consideration the average number of occupants per vehicle, the approximate hourly costs per vehicle delay and commercial vehicle delay, the average costs per secondary incident involving or not involving property damage, and the average costs of incidents involving persons in critical condition or involving fatalities, the study concludes that New York’s HELP program operates with a benefit-to-cost ratio ranging from 2.14:1 to 2.68:1. With less conservative estimated figures, coupled with the avoidance of just one fatal incident (at an ascribed savings of $1 million) the benefit-to-cost ratio would greatly increase to 13.2:1 to 16.5:1.

The Florida Department of Transportation’s Road Rangers were found to have an even higher benefit-to cost ratio in the Review and Update of Road Ranger Cost Benefit Analysis Final Report, a study published in January 2012 by the University of Florida Center for Urban Transportation Research. A survey of 19 agencies, including the Florida Highway Patrol, other law enforcement, fire and rescue, and EMS teams, from 1995 to 2009, derived benefit-to-cost ratios for Florida’s Road Rangers from 4.6:1 to 42:1, with a median of 9.45:1 and an overall mean benefit-to-cost ratio of 12.4:1 In other words the benefits of the SSP program equal 12.4 times the SSP program costs.

One example from the study even found that while the 2010 costs of the Road Ranger program were about $20 million, the calculated benefits were about $134 million, yielding a benefit-to-cost ration of about 6.69:1. The major benefits of the Road Ranger program, as is the case with Safety Service Patrols in most states, were identified as reductions in traffic delays (also reducing fuel consumption and emissions), improved traffic flow, and reduced secondary incidents.

Benefit-to-cost studies also take into account reductions in secondary crash accidents and property damage, which are both frequently more severe than impacts associated with the primary incident according to the US Department of Transportations’ September 2011 Intelligent Transportation Systems Benefits, Costs, Deployment, and Lessons Learned Desk Reference: 2011 Update. With these additional benefits evaluated, the report finds that the ability of the St. Louis Motorist Assist program to lower secondary crashes annually by 1,082 was a key factor in its valuation analysis of safety data from the St. Louis metro area from 2000 to 2008.

Motorist satisfaction, which is identified in a few studies, increases with the presence and/or assistance of Safety Service Patrols. As described in the paper, Benefits of Traffic Incident Management, published by the National Traffic Incident Management Coalition, “Traffic Incident Management (including Safety Service Patrols) increases public satisfaction with government services.” In a statewide citizen survey conducted by the Maryland Department of Transportation, 98% of motorists surveyed ranked road clearance as “very important.”

In a similar survey for Tennessee’s Safety Service Patrol 99.9% of the respondents rated the program as “excellent.” And the state of Florida conducted a survey in the fiscal year 2011-12 in which 480 respondents rated their level of satisfaction with the Road Ranger services as “satisfied” to “extremely satisfied” at the levels of 90% for professionalism, 91% for respectfulness, 93% for helpfulness, and 92% for competence.

Overall states report that consumer satisfaction with Safety Service Patrols is typically quite high, reflected in the thousands of laudatory comment cards and letters from assisted motorists received each year by the operating agency. Some motorists even send checks (which are returned) to pay for services received.

While assisted motorists are grateful for the help they receive, Safety Service Patrols contribute so effectively to smoothing out traffic delays and clearing up vehicle incidents, that motorists may often be unaware of the extent of the benefits. Rebecca M. Brewster points out that studies continue to demonstrate that when SSPs are on-scene to assist with minor incidents and traffic control, incidents are cleared and traffic flow is restored more quickly, reducing congestion and limiting the safety risks that come with traffic queues.

“There are still so many social benefits and costs avoided that we do not include in our evaluation,” reports Jason Chou, for example, the cost of towing, lawsuits and police time for enforcement. “You can easily think of many other benefits associated with [Safety Service Patrol] programs but [it is] hard to quantify them.”

In addition to safety and convenience, motorists also benefit from indirect financial savings as a result of the use of Safety Service Patrols. “When commercial vehicles are stuck in traffic incidents and the resulting traffic queues, the costs begin to mount quickly– wasted fuel, driver time, and the potential for missed delivery windows,” explains Brewster. “All of this adds to the cost of freight transportation, which ultimately adds to the costs of consumer goods.” Though benefits such as this are not currently included in the methodologies used to analyze benefit-to-cost ratios of Safety Service Patrols, it is an example of additional hidden costs that are reduced as a result of the work of SSPs. For the past several years, ATRI has collected motor carrier operating costs. From its most recent data, Q1 2010, the average per-hour cost to operate a commercial vehicle was $59.61. Brewster suggests one might, “multiply that by the number of trucks you see stuck in any traffic incident and you can begin to understand the magnitude of the problem.”

The FDOT Road Rangers have received overwhelming praise from motorists as a result of their services.

Chou and Miller-Hooks elaborate on this point, “Savings incurred by drivers include costs of towing, minor repairs, changing of tires, as well as savings to the local community in terms of reduced fatality rates, and thus, reduced lawsuits, roadway closures, and the use of forensic teams.” The National Traffic Incident Management Coalition’s paper also references societal savings in lost work hours due to traffic delays, fuel, and vehicle repair costs due to prompt removal of debris, though these cost savings are not included in any benefit-to-cost analysis studies.

To the extent that Safety Service Patrols mitigate non-recurring congestion, they reduce the fuel consumed by vehicles idling in traffic, which in the aggregate has a palpable impact on air quality. Florida’s Review and Update of Road Ranger Cost Benefit Analysis Final Report reports that Carbon Monoxide (CO) and Volatile Organic Compounds (VOC) are reduced in most cases with increased speeds that occur when traffic delays are mitigated and highway speeds increase.

Despite the quantifiable and difficult-to-quantify benefits of Safety Service Patrols, states still seek to reduce their capital, operating, and administrative costs and to increase benefits. Contracting with private sector operators and implanting revenue-generating sponsorships are two attempts to reduce public sector costs.

The benefit-to-cost ratio in states using Safety Service Patrols are, to-date, overwhelmingly positive, with states citing increased roadside and motorist safety, decreased delays and secondary incidents, and decreased costs associated with roadside incidents, along with unanimous motorist satisfaction. The Virginia Center for Transportation Innovation and Research, the Virginia Department of Transportation’s research division, reported the overall savings from VDOT’s SSP program to be nearly five times the cost of the service, for a 2012 savings of $10 million, prompting the department to expand SSP coverage beyond the current coverage area in northern Virginia, Fredericksburg, and Hampton Roads.

As states address significant budget deficits and challenges, Safety Service Patrols are subject to greater scrutiny and measurement to avoid cuts and elimination. To facilitate regular evaluation of benefit-to-cost ratios of SSPs, Dr. Elise Miller-Hooks[2] and her students at the University of Maryland in May of this year completed the development of a user-friendly tool, called the SSP-BC Tool. Using Microsoft Excel/Access, the tool standardizes and simplifies Safety Service Patrol benefit-to-cost ratio estimation and promises to create consistency, and therefore added confidence, in the validity and reliability of benefit-to-cost study results.

According to the I-95 Coalition project database details, the tool was designed to support benefit-to-cost ratio estimation for roadways with existing programs, making it widely available. The SSP-BC Tool software uses a simulation-based method to measure each of the four key traffic incident management components addressed by SSPs: traffic delay, fuel consumption, emissions, and secondary incidents. The tool pulls data directly from the simulation results and regression-based estimates for travel delays and fuel consumption, from computations for emissions and secondary incidents, and from publicly available sources for wages, fuel costs, traffic composition, and monetary conversion rates.

A comparison between the previously obtained benefit-to-cost ratio in the Chou/Miller-Hooks study and the benefit-to-cost ratio obtained using the SSP-BC Tool was made and similar results were obtained. The quantitative advantages offered by the new SSP-BC Tool, combined with the benefit-to-cost studies already on record and the unanimous motorist satisfaction with Safety Service Patrols bode well for the future of SSP programs in place and the implementation of new SSP programs in congested areas where they do not currently exist.