Precast bridge segments reduced construction time for two bridges on M-115 in rural Michigan. Photo credit: Michigan DOT.
Several innovations, including performance-based contracting, are being implemented in the reconstruction of a two-lane rural road in Clare County, MI, as reported in the Federal Highway Administration’s latest newsletter.
The 5.5-mile-long (8.8-kilometer-long) project is on M-115, a trunkline route that serves as a primary connector for summer tourists traveling from the metropolitan Detroit area to northwestern Michigan. The Michigan Department of Transportation received a $1 million Highways for LIFE grant for its use of innovations on the project.
The original roadway is concrete pavement placed in 1940 and later overlaid with asphalt. This year, the state chose Central Asphalt Inc. of Mt. Pleasant, MI, to rebuild the road-working under an innovative $4.5 million performance-based contract.
Performance contracting is an approach in which the contractor is responsible for achieving defined goals and proposing how it will achieve them. The contractor is awarded incentives or assessed penalties based on its performance against the contract goals.
For M-115, Michigan DOT based the contractor selection on both best-value qualifications and price, said Jack Hofweber, development engineer for the agency. The state set goals in several areas, including the date the roadway would reopen to traffic, pavement performance, work zone safety and motorist travel delay.
The contractor began construction by removing the existing asphalt overlay with a milling machine and rubblizing the concrete. Rubblizing the concrete and then placing a crack relief layer of open-graded hot-mix asphalt is a method designed to eliminate reflective cracking, said Hofweber. Next the contractor laid down a leveling course of hot-mix asphalt, followed by a top course.
The contractor proposed the pavement design to better ensure pavement performance during the warranty period. The contractor warranted the construction of the new roadway for five years, Hofweber said. If significant distresses develop in the form of rutting, cracking or raveling during that time, the contractor must repair the damage at no cost to the state.
To speed construction and meet motorist travel delay goals, the contractor added a temporary travel lane alongside the existing roadway. The temporary lane allowed traffic to continue flowing in both directions during construction, Hofweber said. A more conventional method would have been to close down one lane for two miles (3.2 kilometers) at a time for construction, then route traffic through - first in one direction, then in another - on the open lane.
"With the temporary lane, the contractor worked on the full 5.5 miles all at once," said Hofweber. "That saved approximately four weeks on the construction schedule." As a result, the driving public was subjected to less inconvenience in the project area.
The contract also called for replacing the superstructures on two small bridges. The new superstructures, said Hofweber, were built with precast concrete beams and deck members -- and that innovation saved considerable time, compared to using cast-in-place construction.
Another innovation was the use of buffalo grass mixture alongside the roadway. Deer-car crashes have been a problem on M-115, and deer do not like to eat the buffalo grass mixture, Hofweber said. Deer did like to eat the previous grass mixture that was planted in the area.
Other innovations include the following:
- Automatically actuated temporary traffic signals sensed the number of cars waiting to cross at both bridge construction sites.
- Rumble strips along the centerline and shoulders give drivers an audible warning if they leave the driving lane.
- Hot-mix asphalt was paved continuously over the bridge approaches and onto the precast concrete bridge decks, creating a smoother transition with less tire-pavement noise.
- The use of a material transfer device in paving the top course of hot-mix asphalt will improve the uniformity and quality of the pavement and the smoothness of the ride.
The two bridges were constructed in May and June of 2008. The road construction began in August and is scheduled to end in November 2008.