Agenda - Public Works Committee - 08/19/2009

Home

CASE # 5 CONSIDERATIONS OF CONCRETE VERSUS ASPHAL T PAVEMENTS By: Steve Jankowski, Assistant City Engineer Background: The Council has inquired about the potential use of concrete for the construction of City streets. Staff reported on this topic at the July 15,2008 Public Works Committee meeting. The primary element in the debate between the use of these two paving materials centers on which is cheaper. Last year staff reported that in general terms the initial cost to construct a concrete street wass approximately 50% - 100% more than asphalt. However Minneapolis had bid a downtown street project last year when asphalt prices were at their peak and received a concrete bid within 5% of asphalt. However, since that time asphalt prices have declined making it more price competitive again. To stay current on this topic staff has requested a cost comparison for the construction of one mile of residential street constructed with both our standard asphalt pavement (32 feet wide from face of curb to face of curb, 1.5 inches bituminous wear, 2 inches bituminous base, and 4 inches of class 5) and an equivalent concrete pavement. This analysis had not been completed at the time of this agenda preparation but will be available at the meeting. Factors other than initial cost Below is a listing the some of the nonmonetary factors which are typically cited when comparing these two paving materials: . Durability - Concrete streets typically have a design life of 40 years, whereas bituminous is approximately 30 _years. When concrete streets are constructed they generally don't require maintenance other than some minor rehab/joint sealing every 12 - 15 years. It is possible that the road wouldn't need to be resurfaced for the entire design life, or beyond. As you are probably aware from our existing street maintenance program, bituminous streets require routine maintenance far more frequently; crack sealing and seal coating every 5 to 7 years and overlays every 15 to 20 years. · Noise potential - In a municipal environment the noise level coming off a pavement is a consideration. Asphalt pavements have a smoother surface initially and are quieter. However as asphalt pavement ages and deteriorates it can exceed the noise level of concrete which is relatively constant throughout its service life. . Temperature Considerations - Concrete pavement is lighter in color and better reflects the sun. As a result it is a cooler pavement. This is considered an environmental plus in terms of combating environmental warming. However, asphalt pavements tend to absorb the sun in the winter and achieves bare pavement quicker following snowfall events. . Light Reflection - Concrete is lighter and more reflective making street lighting more effective.