Suppose you overheard a reference to a “preservation law” — what would you expect it to be about? Some kind of environmental issue perhaps, maybe protecting an endangered species or something like that? Well, preservation is not just for the natural environment; it applies to the built environment too, and that includes our roads. In this edition of the RoadReady newsletter, we’ll look at the implications of a new legislative emphasis on pavement preservation in the U.S. via MAP-21.
Preservation and Legislation
The 2012 federal surface transportation bill, known as the Moving Ahead for Progress in the 21st Century Act (MAP-21), includes some important provisions related to pavement preservation. It recognizes pavement preservation as one of the purposes for establishing the National Highway System, and makes pavement preservation projects eligible for funding under the Act. The bill emphasizes preservation as a focus of planning and asset management practices for agencies that maintain a transportation network.
MAP-21 also provides a definition of what pavement preservation means. The Act defines “pavement preservation programs and activities” as referring to “programs and activities employing a network level, long term strategy that enhances pavement performance by using an integrated, cost-effective set of practices that extend pavement life, improve safety, and meet road user expectations.” Fundamentally, pavement preservation needs to be included as a consideration in practically every aspect of our road network. In the next sections, we’ll look at different ways in which pavement preservation factors into multiple levels of transportation programs.
Every Level of the Organization
By emphasizing pavement preservation as part of agency planning, MAP-21 offers a reminder that all levels of the organization have something to contribute. The contractors and crews who do pavement preservation work need to understand how to correctly apply the proper treatments, of course. However, road networks also need systematic asset management to provide an approach for when to choose pavement preservation, which kinds of preservation treatments to apply, and selecting the projects where they will be used. This requires leaders and planners to understand how pavement preservation fits in with other construction activities and the operation of the transportation network.
Every Pavement Condition Level
Preservation is not just for pavements in need of repair. Just think about the meaning of the word — if you want to “preserve” something, you’re trying to keep it in the condition it’s currently in, so it’s best if the thing is already in the kind of condition you want. Most pavement preservation strategies are actually most effective on pavements that are performing relatively well. These are preventive maintenance treatments like seals and thin overlays to improve pavements while they are still in good condition to extend their service life.
A preventive maintenance treatment is cheaper than rehabilitating a distressed pavement, and a cost analysis will commonly show that early treatment is more cost-effective than waiting until more intensive repairs are needed. This is why pavement maintenance decisions are more complicated than simply fixing the worst roads first. Still, pavements that are not in as good a condition also need some type of preservation while you work on coming up with the resources to bring them up to a higher level. This is where patching and pothole repairs come in, to maintain at least a minimum standard until the pavement can be rehabilitated to good condition.
Every Level of the Pavement
The design of a pavement contributes a lot to the feasibility of a pavement preservation strategy. While a preservation treatment may be able to address surface distresses in the pavement, this is of little use if defects in the underlying structure cause those distresses to promptly reappear. As a result, the effectiveness of pavement preservation also depends on a thorough structural design for all layers when the pavement is constructed. Design approaches that take this into account, such as perpetual asphalt pavements, can work in conjunction with pavement preservation to achieve significant increases in pavement life, together with reductions in maintenance and life cycle costs.
Over its lifespan, a pavement experiences a lot of wear and tear. As MAP-21 recognizes, pavement preservation is critical to ensuring that it functions properly and safely for a long time. If we take good care of our roads, they’ll take good care of us.