CalHar Construction Inc.

Building the first publicly-built segment of a concrete biking and hiking trail called the Six Cities Trail and setting a railroad bridge in the middle of a forest is a challenge, concedes Don Callaham, president of CalHar Construction Inc. “If you were standing there before we started and looked into this thick forest where this bridge had to go and thought about the crane and the large pieces of equipment and precast material, you’d wonder how we were going to get all this stuff back there,” Callaham muses.

“Not only were we able to accomplish that, but we did it without taking out any trees additional to those on the original plan to be re­moved. It’s pretty impressive when you stop to think about it that we were able to pull that off with very little impact to the existing conditions.”

The 314- mile long, $750,000 paved concrete trail was designed for access by people with disabilities so it had to meet the standards of the Americans With Disabilities Act (ADA) for concrete texture, paving, incline and other features. One of those requirements was that the portion of the trail that entered an underpass under tracks owned by Dallas Area Rapid Tran­sit (DART) could not have a grade greater than 2 percent.

The grade slope starts at an estimated 600 to 700 feet before the 15-foot-high underpass on the east side. “The grade to the west was not as critical, because that grade tended to be somewhat lower than back to the east,” Callaham explains.

“It’s a really nice winding trail,” Callaham declares. “It’s really peaceful. It follows the curve of the creek, weaving back and forth.” The trail is named after the six suburbs of Dallas along I-75 that it eventually will link.

The section in Allen, Texas, that CalHar started in February 2010 and completed in June 2010 will be linked with app­roximately 2 miles of trail that was built on privately developed commercial land. “You don’t feel like you’re in the city, but you’re within city limits,” Callaham points out. “I think their master plan is for 15 miles of trail inside the city limits of Allen. It’s pretty substantial.”

Precast Bridge

The precast concrete arch bridge is 48 feet long by 24 feet wide and was in 17 pieces that required 11 truckloads to transport to the site. A foundation had to be poured in place. “This is an existing railroad and railroad embankment, although not currently in use,” Callaham states. “We excavated the embankment and removed a section of track, built the foundation, and then we brought the bridge pieces in and started erecting the bridge pieces.”

When the bridge was erected, the embankment was built back and the railroad tracks replaced. Although DART owns the tracks, they are not being used yet for passenger service. The tracks may be used for freight trains, so the bridge had to be designed to withstand a heavier train. “They wanted to know that they weren’t limited by the bridge’s capacity,” Callaham explains.

Another factor in the project’s design was the depth to which the trail had to drop to clear the existing railroad tracks. “Because the area is in a flood plain, a lot of drainage work was associated with the bridge to get the rainwater away from it so the trail wouldn’t be flooded in that area,” Callaham notes.

No Way Out

Construction of the bridge and trail started at the point furthest into the forest. “We paved our way out,” is how Callaham describes the pro­cess. “We started at the deepest ends of it so we didn’t have to work over ourselves. Once you built the bridge – once you make that imp­rov­ement – you can’t get equipment to the other side of the work, at least not big equipment. We had to build all the west side imp­r­ovement – which is where the majority of the detail work was – box culverts, drainage work. I think we put down 690 cubic yards of riprap for erosion control under I-75 as part of this pro­ject.”

Much of the project was self-performed. One of the three subcontractors worked on the erection of the precast bridge. “We had a subcontractor come in with a crane and pick the pieces up and set them for us,” Callaham notes. Another subcontractor worked on erosion control, and a third sealed the sidewalk.

“We brought in a contractor to seal the joints to make sure they were of a quality level high enough that the city would accept them,” he says. “We wanted that done by a contractor who could see it would maintain the architectural look they were after, only in the sense that it had to be a very clean finish to meet ADA criteria. I think my guys do some of the best concrete you see poured. The fit and finish of the concrete is about as good as you’ve ever seen.”

Masonite forms were used for the trail to give it its meandering curves. Accomm­o­da­tions have been made to widen the bridge if DART decides to add more tracks. The concrete is placed on compacted soil with 2 inches of cushion sand underneath it. Callaham estimates approximately 60 truckloads of concrete were poured in place for the trail.

Callaham founded CalHar in 1992. It specializes in underground utility, water, sewer, bridge and concrete work. “We do anything that moves water, but we don’t build water features, per se,” he says. “We do not go after flat work like parking lots or things like that. We don’t mess with that or specialty things.”

Based in northern Texas, the company’s business extends from Waco to the Red River and from Weatherford to Tyler. “The people we work for know they don’t have to watch us, that we are going to police ourselves,” Callaham emphasizes. “We do good work and I think that and being able to pay our bills is more important to them than anything.”

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