Restoring the heart

Feb. 2, 2018

Major corridor undergoes rehabilitation in downtown Manchester, N.H.

If one were to do a Yelp search for the best restaurants in downtown Manchester, N.H., a number of the top-rated spots would be found on Elm Street, a key thoroughfare that stretches from the south end to the north through the heart of the Queen City.

This particular corridor is in a crucial location, as it passes by Manchester City Hall. It also houses the Southern New Hampshire University (SNHU) arena, home of the Manchester Monarchs, the city’s minor-league hockey team. The 12,000-seat arena also hosts a number of concerts and conventions. A minor-league baseball team, the New Hampshire Fisher Cats, plays just a few blocks away from Elm Street, so the corridor is often bustling with activity.

As such, when the time came for the four- to five-lane road to undergo rehabilitation, officials with the city of Manchester allocated funding not only for repaving, but for a complete streets design approach to accommodate a variety of transportation modes that included bicycle, pedestrian, vehicular and transit.

Showing its age

Elm Street measures about 60-70 ft wide in pavement width, and until last year, it had not undergone much in terms of reconstruction for a couple decades. “The road probably hadn’t been repaved or had a lot of maintenance done to it probably since the mid-90s,” David Winslow, project engineer for the Manchester Dept. of Public Works, told Roads & Bridges. “So you’re talking 20 years—and it was showing its age.” He added that the road was significantly cracked and had a slew of visible utility patches on the pavement.

As rehabilitation became a clear necessity, the opportunity to incorporate the complete streets design was touted by transportation officials. “There’s a lot of advocacy for putting transportation facilities for bicycles and such in town for the downtown area,” Winslow said. “So we looked at where we could put the bicycle lanes in—and it seemed to make sense without impacting traffic operations all that much.” Adding the bike-friendly aspects along the corridor also meant that Elm Street would get a road diet, reducing the four-lane section to three lanes in order to add room for bicycle lanes along the road. The city of Manchester also decided on incorporating high-visibility crosswalks in certain problem areas for pedestrian crossings on the corridor.

Throughout the timeline of the project, which lasted from May to November of 2017 for the construction phase, the city of Manchester maintained an ongoing PR campaign to let the public know when they would be paving on the 2.5-mile stretch of Elm Street. This helped keep the city a step ahead, curbing a lot of the questions and complaints from residents about the roadwork.

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.

A road diet made for the right multimodal mix on Elm Street.

A showcase street

The total asphalt tonnage used in paving Elm Street came in at 12,500 tons. The compaction level achieved on the project was in the 93-94% range, exceeding the 92% requirement of the contract.

Work on the final section of Elm Street was completed a week in advance of the Nov. 7 deadline. While the total cost savings from using recycled material on the project is hard to pinpoint, if the same project used a mix with all virgin material, according to Charbonneau, the added cost would be $5 per ton. Thus, using 22% RAP provided a savings of around $62,000.

Another element of the project that used recycled material involved the installation of 50 permeable tree wells along Elm Street using 100% recycled tire rubber.

Such achievements on the project are part of what earned the Elm Street Rehabilitation project a Roads & Bridges/ARRA Recycling Award for 2018.

The final product, in the eyes of Manchester officials, provides a boost for the businesses along Elm Street and enhances the downtown experience for residents and visitors. “We have a lot of people from out of town coming to the arena and other events, and when they drive downtown they see a brand new street which looks nice,” Winslow said. “It’s the showcase piece for downtown or even just the city in general.”

About The Author: Bruns is associate editor of Roads & Bridges.

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