By: William Jamieson
The Utah Department of Transportation (DOT) recently conducted a live test of PSS rumble strips on I-70 near Green River. This location was selected because of high average daily traffic (ADT) and drivers’ speeds. While the posted speed limit is 75 mph, drivers often exceeded the speed limit. Speeds of 80 mph+ were observed throughout the test.
In 2009, PSS introduced RoadQuake Temporary Portable Rumble Strip, a traffic safety countermeasure that alerts drivers to changing road conditions. Designed to reduce accidents and save lives in work zones, RoadQuake rumble strip protects drivers, passengers and highway workers. PSS introduced a modular version, RoadQuake 2, in late 2011.
It was rainy that morning on I-70, with ambient temperatures around 70°F; the asphalt pavement temperature was estimated at 85-90°F during the two-hour test.
About a dozen Utah DOT engineers, from the central office and District 4, witnessed the test.
Prior to the live test, PSS staff introduced RoadQuake rumble strip to the assembled engineers, as many had never encountered the device. Tests in other states were described, as were rumble strip standards issued by the Texas and Montana DOTs.
The Utah DOT engineers were then shown how to assemble RoadQuake 2, as three 45-in. sections make one 11-ft strip. The introductory session concluded with a Q&A session.
After traffic control was in place, including a “Rumble Strips Ahead” temporary sign, two arrays of three strips each were placed about 50 ft apart in the same travel lane. The strips were placed on 10-ft centers.
Most tests are conducted to determine if PSS rumble strip performs effectively.
State agencies want to know if the strips:
- Alert drivers to upcoming changes in road conditions;
- Remain in place, with little movement; and
- Stay together or disconnect.
PSS rumble strips demonstrated their effectiveness in the test. A few days after the test, several Utah DOT engineers reported their observations of performance:
- “. . . positively affected work-zone traffic speeds”;
- “Any movement . . . is uniform and longitudinal. They do not shift or twist within the lane . . . [they] do not come apart”;
- “. . . did not move off the ground during several, triple-trailer semi impacts . . . forward movement was minimal”;
- “Virtually no movement from passenger cars and pickups and very little movement from semi tractor trailers and heavy trucks”; and
- “They stayed well-connected together during the entire demonstration.”
As demonstrated in Utah—and in hundreds of hours of tests and demonstrations—PSS rumble strip arrays show little movement in traffic. They remain in place in a variety of weather conditions and on many different road surfaces in posted speed limits of 75 mph or less.
More importantly, PSS rumble strip, which is designed to reduce work-zone accidents and save lives, alerts drivers to changing road conditions.
