Engineer explains ‘hop-scotch’ street work

In Tuesday’s Post Scripts column we asked if there was a reason for the “hop-scotch manner” in which city streets are being stripped for the ongoing overlay project.
There is, according to Tim Mader, city engineer.
“I can tell you that one reason for this ‘skipping around’ is that we are mostly stripping — aka ‘milling’ — the existing asphalt surfacing only on curb-and-gutter streets as opposed to those street with open ditches,” Mader said. “This may create an appearance of the contractor randomly skipping around when he is simply completing one curb-and-gutter street before moving over to the next curb-and-gutter street.
“This is especially so where a given street has open ditches in some stretches and curb-and-gutter in others.”
The reason for milling only on curb-and-gutter streets is simple, according to Mader.
If the contractor did not strip off the existing inch-and-a-half-thick layer of asphalt — which was installed 25 years ago — before laying down the new inch-and-a-half-thick layer, the edge of the road would be 3 inches thick at the existing gutter.
This condition could cause vehicle tires to drop down into the gutter more suddenly, which could make driving uncomfortable or dangerous.
Mader said the contractor also explained that they prefer to strip the “through streets” first for the purpose of better traffic maintenance during the asphalt lay-down process.
“Combining this preference with the fact that we’re only stripping asphalt off of curb-and-gutter streets can make it difficult to understand the contractor’s mobilization process,” Mader said.
Yet another reason for the seemingly random stripping is that the contractor, in some cases, is also stripping the city streets where they intersect with state routes (Louisiana Highway 13, U.S. Highway 90, for example) in order to smoothly tie in the new overlay with the existing highway surface.
Besides all of that, it’s basically the contractor’s choice.
“For most of the various items of work to be accomplished in a street overlay project, it is left up to the contractor to decide how to mobilize around on the job, that is, what to do first, where to go next and how to finish it up,” Mader said.