A reader recently asked me why I-75 is being rebuilt with concrete pavement from about State Rt. 582 north to just south of the I-475 split near Perrysburg, while the rest of the ongoing widening and reconstruction down to the north side of Findlay is using asphalt-mix pavement.
The Ohio Department of Transportation explained that for the northernmost I-75 contract, bidders were allowed to quote prices for both concrete and asphalt, but for the sections farther south, asphalt was specified because of soil acidity. Acid soils compromise reinforced concrete’s longevity, state engineers said.
In situations where either concrete or asphalt is suitable, ODOT considers the life-cycle cost of the two materials to be equivalent. While concrete is more durable than asphalt, it’s also more expensive to build. Asphalt, meanwhile, can be maintained by grinding off the top few inches and paving a new surface, a repair method that doesn’t work with concrete.
And while reporting on the progress of ODOT’s interchange reconstruction at Central Avenue and I-475 in Sylvania last week, I noticed that asphalt was used to build the new Central alignment but concrete was used for the new freeway ramps.
Project officials told me that’s because ODOT now specifies concrete for all interchange ramps. Ramps have more concentrated traffic and are curvier than mainline roadways, they said, so concrete’s durability is a bigger advantage for them.
A co-worker, meanwhile, asked why trucks are directed to use the left lane in some of the I-75 work zones. That answer I didn’t need to get from ODOT.
In work zones where traffic is crossed over to one half of the freeway and the shoulders are used as travel lanes, truckers are instructed to use the lane or lanes that don’t include part of the shoulder. Highway shoulders are not always built to the same design standards as travel lanes are, and heavy truck traffic breaks their pavement down.