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Super 70 Project
Concrete, Cars and ‘Mountain’ Moved
for Hoosier Highway
by Steve Kaelble
Sometimes it’s easier to build a mountain than move a railroad. That was the lesson learned during the Super 70 highway reconstruction project under way in Indianapolis.
The $175 million project is roughly halfway through the removal and reconstruction of 6 mi of Interstate 70 just east of downtown Indianapolis. The original highway was built in 1971, and though it has emerged as the busiest stretch of interstate in Indiana, it has never been replaced.
Cash Canfield, department manager with engineer American Structurepoint Inc. of Indianapolis, says the state simply could no longer afford to maintain the deteriorating highway, which carries as many as 180,000 vehicles daily.
The Super 70 project will result in all-new, 16-in.-thick concrete on the roadway. That includes new decking on 28 bridges over city streets and railroads. It also involves bringing the highway up to today’s standards, including wider shoulders and higher bridge clearance.
An Indiana ‘Mountain’
In most ways, the new road will be much like the old—same right-of-way, same number of traffic lanes, same interchanges.
But when it became clear that it would not be feasible to divert rail traffic while lengthening a railroad bridge that currently runs over the highway, designers chose an option that has come to be known as “Mount Sherman,” the part of the project that is the most dramatically different and has turned the most heads during construction.
Raising “Mount Sherman” involves building the roadway up about 60 ft and over the existing railroad bridge as well as a nearby bridge that carries Sherman Drive over the old highway. By the time the project is done, some 300,000 cu yds of dirt will have been trucked in to create the “mountain,” says Pete Jerrell, assistant project manager of Chicago-based Walsh Construction Co., the contractor.
At the peak of the hill will be the Super 70 project’s only new bridge, a three-span structure with concrete beams up to 140 ft long that will soar above the railroad bridge and Sherman Drive bridge.
Crews built a temporary retaining wall to hold the hill in place, right next to five lanes of maintained interstate traffic speeding past at the bottom.
“We knew that was going to be the biggest challenge of the job, so that’s where we started,” Jerrell says.
Crews worked 24 hours a day, seven days a week early in the project to prepare the retaining wall and start to fill in the hill. They piled sand adjacent to the wall and dirt elsewhere. Upon completion of one side of the roadway, they plan to essentially bury the temporary wall with dirt on the other side, building up the other half of “Mount Sherman.”
Though traffic on Sherman was maintained through most of the construction, it was temporarily shut down in June while the massive beams for the new bridge were set into place.
Raising the road 60 ft may seem like a radical solution, but in the end it made the most sense, Canfield says.
Though the highway project is not adding travel lanes, it is widening the right-of-way by increasing the inside shoulder to 14 ft—from 7 ft or less. That means that the railroad bridge would have had to be lengthened to cross the wider highway right-of-way.
Engineers were told that the railroad line could not be closed for more than a few days, so the only options were to build a temporary railroad bridge over the highway, or build up and over. Canfield says the costs would have been similar, so the up-and-over plan was chosen.
Dealing with Hoosier Weather, Utilities
The new mountain wasn’t the only hurdle.
The fast-track Super 70 project started with a weather-related time crunch that set it back several days even before major construction work could begin in late February.
A late-winter snow arrived just as it was time to lay down the striping that would divert westbound traffic over to the eastbound lanes so demolition could begin.
Utility issues also are inevitable with a project of this size.
“We had lots of utility work and some unforeseen problems, such as finding pipes that weren’t supposed to be there and not knowing who the utilities belonged to,” says Monty Mason, Indiana Department of Transportation project supervisor for one section of the roadway.
Crews came across a large water line that had not shown up on utility maps. And they found fiber optics and railroad cabling closer to the construction area than first anticipated.
These kinds of utility problems resulted in mostly minor headaches and delays, Mason says.
Still, none of the utility issues proved insurmountable, and with most of them solved, work on the remainder of the project is now progressing quickly.
Because one goal was to bring the highway up to current standards, some of the overpasses needed to be raised to allow more clearance for city streets underneath. But the project did not call for new bridges.
Instead, the bridge beams were jacked up the required amount—2 to 3 ft—and concrete pedestals poured to fill in the gap underneath, Jerrell says.
Traffic Reconstruction Central
The other major challenge of the Super 70 project was traffic control. Though the state in 2003 took the bold step of entirely closing a downtown section of the highway for the “Hyperfix” reconstruction project, this time the choice was made to maintain both directions of traffic on one side of the interstate during reconstruction of the other.
A total of five lanes of traffic are maintained at all times—three in one direction and two in the other. A special concrete barrier down the middle is moved twice a day, allowing three lanes of traffic coming into downtown during morning rush hour and three outbound lanes during the afternoon rush.
To enhance driver and construction worker safety, crews have shut down exit and entrance ramps along the project route. The state, meanwhile, has reduced the speed limit to 45 mph and has banned most large trucks, diverting them onto the Interstate 465 loop around the city.
The result has been a remarkable safety record, says Kirk Stafford, INDOT project engineer for a portion of the project.
“The road has fewer accidents with injuries this year than last,” he adds. “We have a safer stretch of road during construction, which is rare.”
Walsh began preparatory work on the Super 70 project in October, including work to begin widening the highway bridges to accommodate the wider right-of-way. It’s a design-build project—just 30% of the plans were completed when it was bid, Canfield says.
According to terms of the contracts, Walsh is responsible for the final design.
The contractor is to complete major construction and reopen all travel lanes by mid-November. The company can earn a bonus of $120,000 per day for completing the job early, up to 15 days. Conversely, a late finish will cost the company $120,000 per day, up to 15 days.
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