Concrete vs. asphalt: a closer look
Making decisions to ensure the highest quality paved trails and greemways.
By Tom Peterson
The July, 1998 issue of the Colorado State Trails News reported that "...one of the persistent debates in the trails world concerns selecting the best type of paving to use for trails." To provide insight into the debate, a session entitled "Asphalt vs. Concrete" was part of the 1998 Colorado Trails Symposium. Both the article and the session at the symposium identified a number of the key criteria that should be considered in the decision making process. These criteria include trail design (ie. width and pavement thickness), cost both initial and long term and maintenance needs and user preference.
Knowing that each trail is unique in terms of its location, design, environment, and intended use, it is important that a thorough analysis be performed so that the most cost effective pavement type is selected. The following is one viewpoint on the issue.
One of the primary criteria if not the most important criteria used to determine the type of pavement should be to consider the opinion of those who will be using the trail or user preference. A paved trail for mountain bikers is not the proper design. The most important factors for most users are 1) having enough room and 2) having a smooth, regular surface. The City of Durango reports that asphalt provides a softer surface and is preferred by joggers and walkers. Tom Hale, County Administrator of Chafee County, stated that walkers and joggers near Salida prefer the smoother, softer, asphalt surface of an existing roadway to a concrete trail that was constructed for them adjacent to a roadway. In addition, the use of trails by roller-bladers, cyclists, handicap users, and parents pushing baby buggies is ever increasing and a majority of these users prefer the smooth, joint-free travel that asphalt provides.
Nearly all would agree that the construction cost of an asphalt trial is significantly less than a concrete trail. Cathy Metz of the City of Durango reported that the cost for a 10 ft. wide concrete trail is approximately $35 per linear foot versus $20 per linear foot for a comparable asphalt path. These numbers (or a 30% to 60% savings using asphalt) are very comparable to other locations around the state. The savings or impact to the overall project cost is less dramatic, but still significant. Of the three examples reported by the City of Durango the overall project cost savings of using asphalt would have been from 4% to 26%. This savings depends in part on the other features of the project e.g. retaining walls, fill material, site work, surveying, etc.
The long term (or life cycle costs) depend on the need for and extent of maintenance, see below for a discussion on maintenance. One maintenance issue that is sometimes over looked in the design phase is that when concrete requires maintenance, it is very costly, whether this is slab replacement or joint grinding. Maintenance of an asphalt trail can frequently be done by agency employees at a reduced cost.
A history (or a perception) of higher maintenance costs for asphalt trails is often times the deciding factor for selecting the trail to be constructed of concrete. A designer or a landscape architect must recognize that the service life of a trail whether asphalt or concrete is not only a function of the quality of the materials used and the quality of construction by the contractor, but also a function of the design and investment level. Maintenance costs of improper designs and low budget trails can be high. It is not uncommon for 2" asphalt trails to be constructed on compacted native soil. Problems occur within a few years and then the maintenance costs of this trail could very well be compared against a 6" concrete trail built on top of a quality aggregate base. When comparing maintenance costs, it is important that apples are compared against apples and equivalent designs are compared.
To ensure the highest quality asphalt trails and paths, we have developed a report entitled "A Guideline for the Design and Construction of Asphalt Pavement For Colorado Trails and Paths." The guideline provides insight on proper design, construction techniques, tips for the proper inspection of asphalt trails and how to avoid common maintenance problems. We encourage trail designers to review the report prior to the design and construction of your next trail. Copies of the report can be obtained free of charge by calling the Colorado Asphalt Pavement Association at (303) 741-6150.
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Updated March 18, 2007