Precast Box Culvert: Madison County, Ill. Bicycle Bridges

Precast box culvert crossings become integrated in a renowned bicycle trail system in Illinois.

By Michael D. Cole

In terms of bicycle trails, the intricately planned system established by Madison County Transit (MCT), located in the southwestern region of Illinois, has emerged as a popular refuge coveted by nearby recreational enthusiasts, while also becoming a project envied by other municipalities.

Developed over the last decade, the rapidly expanding and near-complete bicycle trail system now spans more than 100 miles of which 75 are operated and maintained by Madison County Transit.

Construction of the trail system, located just east of the Mississippi River and only a short drive from St. Louis, has sped forward with a Lance Armstrong-like speed since MCT first developed the idea back in the early ’90s. Today, the trail has become such an engrained aspect of daily life for many in the region that MCT has even equipped all the commuter buses in its system with bicycle racks for hybrid travelers.

Remarkably, the MCT bike system, though situated in a traffic-congested metropolitan area – woven with Interstates 55, 70, 255 and 270 – is virtually grade-crossing free as careful planning will ensure bikers a trail system free of traffic crossings.

Those responsible for building the trail credit the liberal use of precast concrete box culverts for helping them achieve that vision.

“If the goal of a bicycle trail development is to minimize disruptions, then this is clearly the way to go,” said Mark Steyer, MCT’s director of engineering in reference to the strategically placed box culverts. “You’re avoiding interruptions for both the car drivers and bikers. As a result, we’ve been able to create a system safe for all types of people using the trail, from children on their roller blades to mothers with their baby carriages. We could have said, ‘No, we’re not going to spend the money, and we’ll make the bikers stop and wait or put up pedestrian crossings that interfere with traffic.’ But that wasn’t our vision.”

Installing precast box culverts strategically beneath select roads created an uninterrupted and worry-free trail system, according to Steyer.

“Using box culverts has clearly been a better economic alternative versus bridges,” said Steyer, who was involved in the project from its inception from both the private and public sectors, working on it for the engineering firm Oates Associates before joining MCT. “(With precast box culverts), we’re putting the top of box culverts pretty much right at the subgrade of the pavement, so we’re not having to go real deep into the ground when you compare that to height considerations for a bridge at 13 feet 6 inches.”

Rails to trails

The trail system was initiated by Madison County Transit Managing Director Jerry Kane, who pushed the idea in the early ’90s of preserving plentiful but abandoned railways located throughout the region for conversion into bike paths.

“Initially the railroads wouldn’t release a section because of the potential of some development around the community,” Steyer pointed out, “but when they finally realized that potential probably wouldn’t come to fruition, we were able to acquire them.” The bike trail plan gained further traction in the mid ’90s as Congress passed legislation to provide government entities and municipalities with funding for converting railway rights-of-way for public usage.

Federal and state funding paid $15 million of the $20 million invested in the MCT bike trails, sparing local residents a heavy tax burden.

As full completion of the system reaches the finish line, its builders say precast box culverts are playing a particularly major role. Steyer noted that while a few culverts are already placed throughout the trail system, he said their most extensive usage is being reserved for the loop-completing trail of the project known as the “Schoolhouse Connector.” Upon completion, Schoolhouse Connector trail will connect six existing trails that are already part of the MCT system and provide a 30-mile loop. In total, six precast concrete box culverts are being planned for that culminating stage of the project, according to Steyer.

“We consider the Schoolhouse Connector to be the missing link, because it will connect the northern part (of the trail system) with a southern part,” added Phil Murphy, a project engineer with Oates Associates, a Collinsville, Ill.-based civil and structural engineering firm. Oates Associates specializes in recreational projects and designed many sections of the MCT trail system. Murphy said the goal is to finish construction of the Schoolhouse Connector in 2005.

County Materials, Marathon, Wis., manufactured the precast box culverts, and Killian Construction, Mascoutah, Ill., installed the products. Killian was awarded the bid for $3.1 million over four other firms.

Precast concrete blazes a trail

In such a unique environment where serene bike trails and busy traffic-filled roads coexist peacefully without actually encountering one another, the system’s builders credit the quick deployability of precast concrete for making it all possible.

“We’re only allowing a 30-day window for these roads to be closed (during trail construction),” Murphy said. “It’s a developing region and daily traffic is increasing – they’ve got to get in there and get out pretty quickly as they put the box culverts in. If we went with cast-in-place, you’re looking at doubling that time, at least. And then of course you always go at grade, which we think would have been hazardous with the bicycles and pedestrians versus vehicular traffic.”

It’s all about speed and ease of installation, according to Steyer. “There’s one place where we’re putting (a box culvert) in without changing the road grade. In that situation we’re giving the contractor 10 days to get in and get out. That’s how quick all this can be done,” Steyer said. “The biggest plus was that minimum downtime. With a cast-in-place (approach), it takes longer because you have to form the walls of the box, set steel, pour the concrete, and sit and wait for it to cure. In this case we excavate, construct an aggregate base, set the box, cover up the road and you’re pretty much done.”

Mike Erickson, general manager of the Illinois pipe division of County Materials, oversaw construction of the culverts used in the MCT trails and noted that a precast approach ensured their uniformity. “You’re doing everything in a controlled environment where nothing changes from day to day,” said Erickson, who noted they were all constructed indoors using standard ASTM specifications. “If you make one piece this way, they’re all going to turn out the same way. That’s the advantage of precast. It’s a lot better result than you get out in the field.”

Erickson said the 8-by-12-foot dimensions of the MCT precast box culverts were particularly beneficial. “There are not many people who have the capabilities of producing them,” he said. “You’re talking about a product that can weigh 30,000 to 40,000 pounds, so it takes a lot of equipment – large fork trucks and overhead cranes – to handle and load them.” Despite those size considerations, the box culverts were transported about 120 miles from Charleston, Ill., to their final destinations along the trail. A special textured finish was applied to the areas of the culverts that served as the floor in order to make them less slick. Constructed in sections 6 feet in length, Erickson said they interlock using a tongue-and-groove system. Murphy said another challenge was that a box culvert placed at one of the MCT trail sites in Edwardsville, Ill., required considerable drainage and storm sewers. “We were fortunate enough to have all the drainage that was associated with the rain water go into inlets and then get carried away,” he said. “We eventually set the box culverts at a height where we could get them to gravity flow to a nearby stream. It prevented us from resorting to pump stations. That would have required a lot of maintenance and some pretty heavy front end costs.” Murphy, who lives near the MCT trail system, said one of the most satisfying parts of the project is to see the bond it makes with the community. “Senior citizens use the trail system quite often,” he said. “They might not otherwise be riding a bike if they had to use the street. It’s been really well received here. That makes it particularly rewarding.”

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