In 2007, the South Carolina Department of Transportation (SCDOT) Strategic Highway Safety Plan (SHSP) established a goal to reduce fatalities on South Carolina roads to fewer than 784 by 2010 – a 25 percent reduction from 2004. Following an extensive, five-year analysis of traffic crash data, intersections were among the nine identified target areas within the Serious Crash Type Emphasis Area. The South Carolina Intersection Safety Implementation Plan (ISIP) was created and indicated 44 percent of intersection crashes occurred at just 1.3 percent of the state’s intersections, resulting in a list of 2,204 candidate sites.
SCDOT’s systematic improvements at stop controlled and signalized intersections were primarily related to signing and pavement marking upgrades. In addition, signalized intersections were treated with low-cost improvements specifically related to traffic signals and associated infrastructure.
It was critically important to SCDOT to implement the improvements quickly and efficiently, so during the summer of 2009, SCDOT advertised a performance-based contract for intersection improvements. Through the SCDOT procurement process, the contract was awarded to 3M, a St. Paul, Minnesota-based company.
As the project implementation proceeded, 3M was responsible for installing ground-mounted signs and pavement markings at all intersections within the project areas. An additional deliverable included an update of the SCDOT asset management system. The benefits provided to the agency and the motoring public from this streamlined process were safer intersections in a shorter timeframe.
Crash and fatality reduction results are anticipated to show a very high cost-benefit ratio for this safety improvement project. Preliminary results already indicate positive improvements during the first year of the project. The SCDOT expects similar positive results across all the improved intersections based on these initial findings and national research data on similar intersection safety improvement practices.
Preliminary statistics are based on simple analysis calculations and are not yet validated using well known Empirical Bayes methods. However, at a cost of only about $4.2 million per year to improve over 700 intersections, it is very clear that the safety improvements implemented have a positive benefit-to-cost ratio, met expectations and—most importantly—have saved lives.
