Willie Nelson Road

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Hillsboro, the county seat of Hill, known for its historic courthouse, outlet center and now its highways?

Interstate 35 has been well known to travelers from across the state for some time on holiday weekends as traffic back-ups in all directions are common from the east-west split.

But a different type of highway issue is putting Hillsboro on the map in construction circles.

Two I-35 reconstruction projects continue to put a new face on the roadway, one north and the other south of Old Brandon Road in Hillsboro.

The new northbound service road from Farm Road 310 past Willie Nelson Road should be open by mid-July.

Opening a new entrance ramp north of Willie Nelson Road will clear the way for the northbound FM 310 entrance ramp to be closed for reconstruction.

It will also lead to the demolition of the Willie Nelson Road bridge, which will close the southbound service road on the west side of the interstate.

Work on the new service-road bridge that will span Highway 81 will get underway at that point.

It is the south project that has researchers, contractors and engineers coming to the area from as far away as Houston to see the latest approach to road construction.

The first concrete pavement using a post-tension design was poured last week north of the railroad bridge in southeast Hillsboro.

While post-tension technology has been used in bridge beams and residential slabs, this will be the first time an extended stretch of roadway has been constructed.

Texas Department of Transportation (TxDOT) Project Manager Charlie Ferry explained that the south project is utilizing two types of construction.

The roadway from Farm Road 310 north to just past the railroad bridge is made of 14-inch thick continuously-reinforced concrete pavement (CRCP).

That is the same pavement used on the interstate from Farm Road 310 south to Farm Road 1304.

But from the railroad bridge north to Old Brandon Road, the new technology is being utilized with nine-inch pavement.

The first 100-foot pour was made Tuesday, May 27, and after working out some kinks, two 300-foot sections were poured Thursday, May 29.

Pouring a section of roadway is no easy task, and in fact, no additional pours were scheduled Friday or Saturday, May 30-31, to give crews time to get cables in place that will allow the paving crew to work without stopping.

The University of Texas in Austin has been the research leader in post-tension roadway construction, and a team from the school was on hand for the initial pour last week, according to Ferry.

The project has generated so much interest that TxDOT officials are requiring visitors to sign in when they visit the site.

Under the design, a series of five-eighth inch cables are stretched the length of each 300-foot pour, and one-inch cables are laid across the roadway.

Both sets of cables are housed in plastic tubing that prevents the cables from bonding with the concrete pavement, which is poured on top of plastic that prevents bonding with the asphalt base below.

“Post-tension is considered a free system that is allowed to move when the cables are stretched,” Ferry explained.

There are two 150-foot cables in each pour that are attached to armor joints on each end and then connected in the middle.

The cables are initially stretched once the pavement is cured to 1,000 pounds per square inch (PSI) density. The final tension is added once it has reached 3,000 PSI.

Small test cylinders of concrete are poured at the same time as the pavement. They are used by TxDOT officials to check the density as it cures.

“The roadway must cure to 1,000 PSI within eight hours for the first stretch,” Ferry said. “There is no time limit to make the second stretch.”

Stretching is done from the center of each pour, where special cutouts are left exposing the cables.

Once the final tension is reached, grout is pumped into the plastic tubing to eliminate the void around the cables.

Rubber gaskets will be placed between the joints to prevent water, dirt or trash from getting under the pavement.

While the process is expected to be more expensive up front, research shows that the nine-inch pavement should last longer than the 14-inch CRCP, Ferry pointed out.

When completed, there will be two 64-foot sections of roadway for north and southbound traffic with an eight-foot section of CRCP in the center to support barrier walls and drainage structures.

Once the first section of roadway is complete, which is currently slated for August, northbound traffic will be switched to the new pavement and work will begin on the east section of the roadway.

The project manager said that he anticipated the pace of the project to increase substantially now that the two-mile post-tension pavement project is underway.

Switching traffic to the new pavement will also allow excavation below the Old Bynum Road overpass.

That new bridge will be built in two sections to assure that there is always access across the interstate at that point.

But the beams on the first section of the bridge can’t be put in place because of the elevation of the existing northbound lanes of traffic.

The switch of traffic will temporarily close northbound exits at Old Bynum Road and Corsicana Highway.

The contractor will be charged with working around the clock to get at least one of those exits back open on a temporary basis, according to Ferry.

During the reconstruction of the east section of the roadway, there will be at least one northbound exit ramp open.

But there will be a period when Corsicana Highway traffic will have to exit at Old Bynum Road as the second ramp is reconstructed.

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