Report analyses multiple ITS projects to highlight cost and benefits
First publishedin ITS International
Overview of ITS projects provides cost benefit insight.
Every year in America cost benefit analysis is carried out on dozens of ITS installations and pilot studies and the findings, along with the lessons learned, are entered into the US Department of Transportation’s (USDOT’s) web-based ITS Knowledge Resources database. This database holds more than 1,600 reports and periodically the USDOT reviews the material on file to draw conclusions from this wider body of evidence. It has just published one such review ITS Benefits, Costs, and Lessons Learned: 2014 Update Report (Publication Number: FHWA-JPO-14-115) which updates the 2011 report in the light of the 325 new studies added subsequently. Topics covered range from a single evaluation on the benefits of alternative fuels to more than 250 on the benefits, costs and lessons learned in arterial management, and there are also examples outside the US.
Throughout the 18 years that the USDOT has been monitoring ITS deployments, one of the most common aims has been to improve safety but the report points out that in 2014, motor vehicle crashes remain the leading cause of death among Americans aged between one and 34 years old. That annual death toll has proved difficult to reduce and the Federal Highway Administration puts the total societal cost of crashes at more than $230 billion per year.
In the preamble to the 130-page report it states that in 2014 Americans travelled for an extra 5.5 billion hours and purchased an additional 11 billion litres (2.9 billion gallons) of fuel because of congestion. It puts the cost of that congestion at $121 billion – a one billion dollar increase from 2013 and equivalent to $818 per commuter. In terms of pollution and emissions, the Texas Transportation Institute estimates the additional carbon dioxide (CO2) emissions attributed to traffic congestion at 2.5 million tonnes (56 billion pounds) or about 172kg (380 pounds) per auto commuter.
In collating and rationalising the findings of the various studies the report divides the individual projects into 16 categories and details key benefits, costs and lessons learned for each category along with reference numbers of highlighted studies. Much of the information has been further distilled into 20 factsheets.
The category with the biggest evidence base is Arterial Management and the report reinforces the point that improved traffic signal control remains one of the most cost-effective ways to improve safety and mobility. It also highlights the ability to utilise traffic control technology during peak pollution periods (to control traffic demand, restrict speeds and ban heavy duty vehicles) in order to significantly reduce the need for other air quality measures. Continuing on the environmental theme, the report collates evidence showing cooperative adaptive cruise control systems can cut fuel consumption by up to 37% and drivers find them easy to use.
Examples and key highlights in this section include the Bay Area Rapid Transit’s smart parking system which not only improved the efficiency of managing the car park and increased parking space utilisation rates, it also boosted ridership. Fifty parking spaces were instrumented at a cost of between $150 and $250 and 15 of these could be reserved while the others were available on a first come basis. Two portable variable message signs located on Highway 24 displayed parking availability information to motorists and survey showed the smart parking scheme had encouraged 30% of respondents to use transit instead of driving alone to their place of work.
In other trials, providing highway drivers with transit travel times and departure information has led to a mode shift from automobile to transit of between 1.6 and 7.9%.
Benefit-cost ratios for selected Traffic Control Systems. Source: USDOT
Lessons learned by San Francisco’s Municipal Transportation Agency during a pilot project to adjust the cost of parking at metered bays according to the demand, were to understand the parking supply and not to underestimate the scope of work.
Perhaps the most spectacular result is Oakland County’s two-phase project to retime 640 traffic signals. This resulted in a benefit-cost ratio of 175:1 for the first phase and 55:1 for the second.
Topping the lessons learned is to commit to acquiring the proper level of staffing and knowledge required for the operations and maintenance of adaptive traffic control systems prior to deployment.
With Freeway Management some of the best returns are in adopting an integrated corridor management (ICM) approach to manage the transportation corridor as a multimodal system rather than individual assets. Estimated costs for a corridor-wide ICM solution range from $4 to $75 million and projected benefit cost ratios are between 10:1 and 25:1 over 10 years.
USDOT continues to encourage the adoption of ICMs and the report says the key lessons learned are to foster champions and organise stakeholders when considering an ICM and then to confirm project responsibility, commitment and expertise.
Another system proving its worth is ramp metering. Kansas City recorded a 26% to 50% reduction in crashes after installing the technology at seven interchanges along an 8km (5 mile) section of the I-435. The report said that level of improvement is not unusual.
Variable speed limits (VSLs) have also been shown to reduce crashes (by eight to 30%), travel time and vehicle emissions through increased uniformity of traffic speed. For instance, implementing VSLs along Wyoming’s Elk Mountain corridor reduced crashes to the lowest level in a decade while a case study on the IH-35 corridor in Austin, Texas found VSLs could cut NOx emissions by 17% on ‘Ozone Action Days’.
Given special mention in the Roadway Operations & Maintenance section were portable traffic management systems for rapid deployment at work zones. The report highlights such systems’ ability to monitor traffic conditions and communicate with drivers to improve situational awareness, harmonise traffic flow and lessen the impacts of reduced capacity.
Findings from various studies show up to a 30% reduction in crashes and 81% fewer dangerous driving occurrences as well as a halving of speeding offences and delays. Benefit cost ratio can exceed 2:1 although a key lesson is that ITS solutions are just one part of a successful work zone management plan.
Much of the Crash Prevention & Safety section is taken up looking at studies of the technology at pilot project or even earlier stages – including Car2Car (C2C) and Vehicle 2 Infrastructure (V2I). The report concludes that crash avoidance technologies have been shown to decrease crashes and reduce driver injury and fatalities by up to 57%.
Reports of projects that did not work are of equal value and one of these is Wisconsin’s rural intersection collision avoidance system at the intersection of US 53 and State Trunk Highway (STH) 77. It installed a ‘Stop Sign Gap Assist’ system which provides information for drivers at stop signs waiting to cross or join major routes that do not have stop signs. Stationary drivers receive information about any danger to their vehicle proceeding through the intersection from vehicles approaching on the cross street.
The results were mixed: Surveys indicated that more than half of respondents believed the signs to be ‘very accurate and very reliable’ and over 30% believed the signs to be ‘accurate and usually reliable’. However, the technology and sign placement seemed to confuse many motorists, and no detectable change in behaviour was indicated while data analysis showed no reduction of crashes following installation of equipment.
The case for weather-responsive traffic management systems is made by results showing they can reduce rear-end conflicts by approximately 22% for moderate volume levels and 43% for high volume. Analysis of incident management systems show some of the highest benefit cost ratios ranging from more than 4:1 to over 38:1.
With complicated evaluations such as that of Transportation Management Centres, the report defines some of the benefits in percentage terms and some typical annualised costs but says these vary widely depending on the type of work the TMC undertakes.
Figures are readily available in the Traffic Incident Management section and include an almost 40:1 benefit cost ratio for the expansion of St. Louis’ Motorist Assist program. Elsewhere, research concerning the Comet incident response program in Portland, Oregon, found that reducing the duration of each incident by just 30 seconds would reduce the costs of delays by $711,300 – the cost of operating the scheme for a year.
Washington DC is highlighted as an example of the benefits in the Emergency Management section as, during a no-notice emergency evacuation, a transit vehicles’ priority system resulted in a 26% time saving for buses without impacting personal vehicle travel time.
Traveller Information systems is another category in which schemes’ aims and scope vary widely them difficult to compare. However, a six-month test of in-vehicle systems in Washington State found users changed their travel routine once out of every 4.2 journeys. Having diverting, the users said they saved approximately 30 minutes in travel time.
An online version of ITS Benefits, Costs, and Lessons Learned: 2014 Update Report can be downloaded free of charge and contains text hyperlinks to individual reports and evaluations on the ITS Knowledge Resource website.