Research and jobsite studies around the United States and other countries indicate that roadways built without shoulders, especially those with over 2” lift thickness, include sharp drop-offs that may lead to serious accidents with possible fatalities.
The problem, according to numerous jurisdictions, is twofold: One, the sharp, vertical pavement edge, when crossed by a vehicle, may cause an abrupt drop, which in turn may be the cause of the vehicle colliding with trees, guard rails and other objects.
Secondly, and on most occasions far worse, the driver overcompensates when steering the car back up over the road edge, often crossing into oncoming traffic.
TransTech has been working with many states and has developed a solution known as the Shoulder Wedge Maker™ (SWM). The TransTech SWM mounts directly on most paver screed extensions against the end gate and provides a 30 degree beveled shoulder edge that gradually transitions wayward vehicles off shoulderless road surfaces and back on with relative ease.
The specifications listed below are made available for your reference only. You are responsible for ensuring that you are using the latest and most up to date specification from your state.
Safety Edge equipment/processes improvements – FHWA evaluation in 2011
Pavement edge drop-off on highways has been linked to many serious crashes, including fatal collisions
Announcment for the requirement of shoulder wedges for binder and top courses
Construction of a Safe Pavement Edge: Minimizing the Effects of Shoulder Dropoff
Federal Highway Administration article explaining the importance of the SWM
Safety Edge brochure from the Innovation Team (I-Team) at the Caltrans Division of Research and Innovation