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Publication Number: FHWA-SA-97-021
Date: March 1997
Temporary work zones are hazardous for motorists and workers. The short duration of most maintenance and repair jobs, such as pothole patching, makes it impractical to install concrete barricades or other formidable types of protection. As a result, the crew often works just a few short steps away from passing vehicles, with scant protection. The sometimes confusing nature of work zones increases the risk of accidents; drivers are suddenly faced with closed or shifting traffic lanes, backed-up traffic, or other exceptions to normal travel conditions.
New work zone safety devices developed or evaluated under the Strategic Highway Research Program (SHRP) can give workers more protection in, and help motorists safely wend their way through, temporary work zones. To evaluate the benefits versus costs of the SHRP devices, a panel of safety experts at the Texas Transportation Institute (TTI) looked at two of the most widely used products-namely, the flashing stop/slow paddle and the opposing traffic lane divider. The flashing stop/slow paddle helps flaggers to get drivers' attention and instruct them to stop or slow down in a work zone. The opposing traffic lane divider is placed along the centerline to alert drivers to a changed traffic pattern, such as when a one-way road is temporarily converted to two-way operation.
In 1994, 706 people were killed in work zone accidents in the United States. It is difficult to quantify the average value of a human life. For the purposes of the benefits versus cost analysis, however, TTI assigned each fatality a value of $2.7 million, a generally accepted figure in calculating the monetary losses resulting from an accidental death. Thus, the 706 fatalities in 1994 came at a financial cost of $1.9 billion to society. Each injury resulting from a work zone accident was assigned a value of $24,800, with a total cost of $122 million; property damage costs were estimated at $43 million.
The TTI panel estimated that using the flashing stop/slow paddle and the opposing traffic lane divider at work zones around the country could reduce the number of accidents by 5 percent. Because the vast majority (86 percent) of people killed in work zone accidents are occupants of vehicles, not part of work crews, TTI apportioned 86 percent of the predicted costs to motorists (road users) and 14 percent to highway agencies.
Realizing that implementation of these two devices would not happen overnight, TTI calculated that the savings apportioned to State and local highway agencies could range between $2.1 million and $4.1 million annually over a 20-year period, after subtracting the upfront costs of purchasing the devices. The savings apportioned to motorists could range between $15 million and $29 million per year.
These benefits more than cover the expense to highway agencies of developing and implementing the safety devices. TTI estimates that the cost of researching, developing, and implementing the SHRP products will total $30 million over 20 years, or $1.5 million per year-less than half of what highway agencies could save every year.
The work zone safety devices developed under SHRP are already making life better for workers and motorists. Here are just two examples:
The following work zone safety devices developed under SHRP are now commercially available:
A ninth product-the remotely driven shadow vehicle-is nearing commercial production.
More detailed information on the benefits-versus-costs analysis of the SHRP products, as well as more than 100 case studies of how highway agencies are using those products, are available at the RoadSavers home page.
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