Joseph S. Toole
by Joseph S. Toole on April 26, 2011
Associate Administrator for Safety
Federal Highway Administration
Every year, State and local highway agencies resurface many miles of existing pavement with new surfaces. A smaller number of miles of pavement are rehabilitated, or completely replaced. In a few locations, brand new highways are constructed. What do these highway surfaces all have in common? An opportunity for innovation! The Safety EdgeSM is a paving technique that costs very little, improves pavement durability, and saves lives.
The pavement edge can greatly affect what happens in a roadway departure. And, records show that every year approximately 20 thousand people die in roadway departure crashes on America's highways. Tens of thousands more are injured or suffer property damage. Countless others recover safely and drive away more alert. The condition of the pavement edge they encounter can mean the difference between death and driving away safely.
Four million miles of public road must be maintained by Federal, State, and local highway agencies in the United States. Every paved roadway has an edge, which is the location where degradation of the pavement and shoulder typically begins. During conventional asphalt paving, the edge of the new pavement is not confined and the result is typically a vertical face on an irregular shaped edge. Settling and erosion of the adjacent aggregate or soil expose this vertical edge, which has been shown to induce tire scrubbing, a factor in some of the most severe crashes. It can also lead to edge raveling or potholes, especially on narrow roads, where vehicles and farm equipment frequently expose and wear the edges.
For years, agencies have addressed the risk of pavement edge drop-off by setting a goal to maintain the shoulder material adjacent to the pavement edge flush with the top of the pavement. Combining the use of Safety EdgeSM with this type of shoulder maintenance has been shown to reduce the total number of crashes nearly 6 percent. Safety EdgeSM projects in place for 8 years demonstrate less raveling than comparable pavement edges using conventional installation – indicating improved pavement durability. Employing the Safety EdgeSM during asphalt construction and rehabilitation projects provides a confined, angled edge that is more compact and less prone to break off. Concrete pavement edges which are typically more vertical, can also easily be installed with the Safety EdgeSM shape.
Why has the Safety EdgeSM not become a standard?
Willingness to adopt or routinely deploy the Safety EdgeSM differs among the States. It may be a question of awareness and education – or actual onsite project experience. Through presentations, training, and demonstration projects, the Safety EdgeSM is being embraced by transportation agencies across the Nation as a welcomed solution for deterring roadway departure crashes.
Contractors are aware of the problem because exposed pavement edge drop-offs are especially an issue of concern to them during construction. However, they have questions about the time and effort required to install the Safety EdgeSM. Various technical experts are also seeking solutions to the longer-term problem of edge drop-offs. For example, safety professionals have a difficult time quantifying the extent of the problem without detailed analysis of individual crash reports. Maintenance personnel spend many hours re-grading shoulders to eliminate drop-offs, but may be unsure how the sloped edge will affect operations. Designers and pavement experts are unsure how to best include the Safety EdgeSM in their projects, and what it will mean to future resurfacing projects.
I pose this question to you – What do you see as the barriers and/or the benefits to implementation of the Safety EdgeSM?