Illinois Tollway Moves to 100% Warm Mix Asphalt

As for the project, crews completed a mill and fill laying down a final surface of SMA. Crews paved 2.5 miles per night and 2 miles per day, when the plant was available and the schedule allowed. If crews were able to complete both day and night work they could pave 4 to 5 miles in 24 hours.

“We were milling 1.5 inches of the mainline and putting down 2.5 inches of SMA,” Curran says. “For the inside and outside shoulders we milled 3-4 inches down to the concrete pavement. Then, we were patching the shoulders and putting a binder and surface mix on the shoulder.”

A 19mm bottom lift and a 9.5mm top lift were laid on the shoulders using a WMA N50 binder and WMA N70 surface with a PG 58-28 asphalt cement. Key pieces of equipment used included a Caterpillar paver, a Roadtec MTV, two Sakai three-wheel rollers behind the paver and one double-drum Hypac finishing roller.

Working through challenges

With every project, contractors are faced with challenges and finding a way to overcome them. For the Tollway project, Curran Contracting’s biggest challenge was the change in staging. “The original plan was to put the traffic on the outside shoulder after it was paved to allow for two lanes of traffic,” Curran says. “When the traffic was first placed on the shoulder we had many immediate failures due to the deteriorated condition of the existing concrete shoulders under the newly placed hot mix asphalt.”

As a result, Curran Contracting had to work with the Tollway to create a new staging plan. “We proposed reducing traffic to one lane for short durations to allow for mainline paving,” Curran says. “We had to coordinate our milling and paving plan to allow traffic to be opened to one lane Monday through Thursday and two lanes during the day Friday through Sunday night.”

Another challenge Curran Contracting faced was coordinating the work between days and nights to allow the DeKalb plant to produce mix for other projects and private customers.

Due to the high-traffic location of the project, Curran Contracting was also required to use alternative transportation for crews to the site. Painted in Curran yellow, crews were transported to and from the site in a school bus.

“Since the job was 37 miles long and the Tollway does not allow personal vehicles to be parked in its ROW we had to have an efficient and safe method to get our people to the job,” Curran says. “We would load all of the crew members at a location off of the Tollway and transport them to the job-site. The only vehicles on the jobsite were the bus and other vehicles necessary to complete the job. The hazard and distraction of 10 or so vehicles parked on the side of the roadway were eliminated.”