How much do they cost?
“Every state department of transportation should be installing continuous shoulder rumble strips on at least all their rural highways this year. They have no investments in anything that are even remotely close to this opportunity.”
Based on FHWA/NYSDOT accident costs for 1993, the prevention of a single fatality would cover the costs to treat over 1,700 miles of highway shoulder.*
The New York Thruway Authority determined that for every $1 spent on the construction of the 7-inch milled shoulder rumble strip, they saved motorists $88 in insurance costs, property damage, lost wages, quality of life, medical expenses and other costs associated with run-off the road accidents. (B/C ratio calculated by the New York State Thruway Authority using FHWA/NYSDOT accident costs. Based on the average number of fall-asleep accidents per month recorded before and after the construction of 7-inch milled rumble strips on over 106 miles of highway shoulder.)**
What Determines Price?
Advances in SPT’s numerically controlled NoisePrint mills have driven a dramatic decrease in pricing since the PA Turnpike introduced the 7-inch milled rumble strip in 1989. Highway authorities have also taken the following measures to preserve the best quality and price in shoulder rumble strips:
Project size has the single greatest impact on unit pricing. Projects in excess of 100 shoulder miles (25 lane miles x 4 shoulders) always receive more competitive bids. Larger projects also guard against the poor performance of prototype machines, which contractors will sometimes risk using on small resurfacing projects.
Rumble Strip only projects:
At first, some highway authorities only constructed rumble strips as part of larger resurfacing projects. Today, however, most construction takes place on stand-alone rumble strip contracts. The larger quantities drive down bid prices, and highway authorities can qualify low bidders better than when rumble strips are a small subcontracted item.
Also, by treating hundreds of miles of shoulder on one project, highway authorities don’t have to wait 7-15 years for the next resurfacing to take advantage of this safety improvement.
*Based on construction costs to treat over 100 shoulder miles.
**Benefit/cost ratios vary with traffic volumes and accident rates. Various agencies across the United States have found BCRs ranging between 20 and 200.