1 week Ago By Mitch Voehl, Windom
Letter to the Editor: It was interesting to me to read the recent comment from the Worthington City Engineer on why he recommended asphalt pavement for the Murray Ave street project. He said, “Concrete streets in Worthington last 50-60 years and then the City applies 2 inches of asphalt to extend the life of the concrete street.” This was a great testimonial for concrete streets as it’s well known that asphalt pavements will require costly routine maintenance to achieve a 50-60 year life.
In fact, I believe Ninth Street in front of City Hall, a concrete street, was at least 75 years old before it was replaced. ADVERTISEMENT In terms of the Murray Ave. project, both concrete and asphalt pavements were bid and both bids came in lower than the project estimate.
In designing pavements, every layer of material, whether it’s concrete, asphalt, or the aggregate below, has a strength value per inch of thickness. In my quick calculations, it appears that the two pavements were not equivalent as the concrete pavement was stronger than the asphalt pavement and the rock underneath. This design resulted in a lower asphalt bid.
When structural equivalencies (strength values) are the same, typically there’s up to a 10% difference in costs with concrete sometimes being less. It costs a lot of money to own and maintain asphalt streets. To get a 30-year life, asphalt needs some sort of maintenance every 2-5 years, which typically involves sealcoating or surface removal and replacement.
It doesn’t take very many years for the total costs of ownership to be equal, with asphalt costing more to own over its life. Without a maintenance plan, asphalt dries out and ends up looking like the dried-out sponge underneath the kitchen sink. There can be occasional maintenance to concrete, but not enough to budget for repairs and it’s often 15-20 years after the initial installation.
Given that, if one adds up the maintenance fees, the overall life cycle cost of asphalt can be as much as 50% higher when compared to concrete over 30 years. The best value for pavement in Worthington is concrete. Mitch Voehl Windom.
