Tree wells using 100% recycled tire rubber were installed along the corridor.
In the matrix
While the city successfully kept the public informed about their presence on Elm Street, coordinating the project schedule itself became quite the hassle as 10 different contractors had to complete repair and utility work along the corridor. All utility work had to be completed before paving could begin, and the city had to juggle an already compressed schedule with making sure the work would be completed apart from the times of major events happening downtown.
Utility work proved to be a major headache for the city to get out of the way before paving. “One of the utility companies putting the fiber optic in, as they started they didn’t realize how tough Elm Street was,” Winslow said. A number of utilities along the corridor slowed down the process of installation.
When construction began in May, contractor Continental Paving at first was limited in the work they could do. “Around June we were able to get started with some sections, and some sections weren’t available to us until some time in September,” Ryan Charbonneau, project manager for Continental Paving, told Roads & Bridges. Elm Street was broken up into eight different work areas, and each section varied in size and had its own unique conditions affecting work production. According to Charbonneau, the most asphalt laid down per day was 2,200 tons of 12.5-mm wearing course. This occurred on the straightest southerly section of Elm with no irregularities to pave around. The average paved was 1,200 to 1,400 tons per day for the top course.
On Continental’s side of the project, the contractor tried to maintain a similar conceptual schedule to each section where they milled. “The general process was mill, shim, pave, and then there was a fair amount of other work—raising structures, new traffic-control signal loops, things of that nature,” Charbonneau said. On an average week, Continental would try to mill about 2 in. off the road, and then try to shim it in by Friday of that given week. Each section carved out of the project usually was completed within the span of two to three weeks, depending on weather and some of the other work going on along Elm Street.
For the work on Elm Street, in compliance with New Hampshire Department of Transportation (NHDOT) specifications, Continental used 22% RAP in their mix, which consisted of a 9.5-mm mix for shim, 12.5-mm mix used on the top course and PG 64-28 binder. The shim course varied in lift thickness, averaging 1 in., while the top course was 1.5 in. thick.
The paving train featured a Roadtec RP190 paver at the front, with some sections using two pavers—one to handle the mainline, and the other to pave in and around angled parking stalls, sidewalk bump-outs and other irregularities. Compaction was achieved with a Hamm 120 for breakdown rolling and Hamm 90 rollers for intermediate and finish rolling. The transporting distances for trucks bringing the mix to the project site ranged from 8-11 miles, depending on the location on Elm Street.
