Construction Crews Raise the Roof in Cowan Tunnel

Mon March 10, 2008 - National Edition
Tim Thornton -ROANOKE TIMES



RADFORD, Va. (AP) The excavator’s big yellow arm reached out, then up, extending two wheels of whirling metal teeth toward the ceiling of Cowan tunnel. When they got there, hunks of concrete and chips of rock fell like a rainstorm onto the rail car below.

Two cars back, approximately half a dozen men from Johnson Western Gunite worked with jackhammers and drills and inserted roof bolts intended to keep bigger pieces of the rock ceiling in place. When the bolts were set, the crew sprayed their work with a layer of shotcrete — concrete sprayed through a hose with compressed air.

If things go well, those crews will raise the roof on about 10 ft. (3 m) of tunnel in a 10-hour day. The tunnel they’re working on in Pulaski County near the Radford Army Ammunition Plant is 3,304 ft. (1,007 m) long.

When they’ve finished Cowan and 27 other tunnels, Hampton Roads will be hundreds of miles closer to Chicago. At least it will seem like it.

The work going on at the Cowan tunnel is part of the Heartland Corridor project, which aims to move freight rail traffic faster and more efficiently by accommodating double-stacked container trains.

“That’s where you put two truck containers on top of one another and haul them by rail,” explained Robert Billingsley, Norfolk Southern’s director of structural projects.

Now those trains travel from Norfolk to Radford before veering south through Bristol and Knoxville, Tenn., to Chattanooga, Tenn., before turning north again. Or they turn north at Roanoke, traveling up the valley to Harrisburg, Pa., before heading west.

With the Heartland Corridor improvements, trains can head north at Bluefield dramatically cutting miles and time from the trip.

“It will take about 250 route miles, or almost a day’s journey, between Norfolk and Chicago,” Billingsley said.

About two-thirds of the project’s $249 million cost will be borne by federal and state governments.

Virginia has agreed to pay nearly $10 million to increase clearances in Cowan and the three other Virginia tunnels on the route and about $15 million to relocate tracks leading into Hampton Roads’ ports.

Virginia also has agreed to put more than $12 million toward an intermodal rail yard in the Roanoke area. Norfolk Southern wants to build it in Elliston, but residents and county officials don’t want it there. Salem officials have asked to have the rail yard built in their city, but people who live near the proposed site oppose it.

At some tunnels along the route — including those at Eggleston and Pembrook — crews will lower the track and move it closer to the center of the tunnel to get 20 ft., 9 in. (6.3 m) of clearance. (The trains are 20 ft., 3 in. (6.1 m) tall, but they build in an extra space just to be sure.) There are a few reasons that won’t work on the Cowan tunnel.

“Number one,” Billingsley said, “there’s a lot of rock at the bottom of the tunnel. Also, there’s a big bridge — a six-span, three-truss bridge — just on the east end of the tunnel that spans the New River. And we can’t lower that bridge. So we’re locked in here to having to take the roof out to gain the clearance.”

When the Cowan tunnel was built approximately 1910, the principal tools were dynamite and shovels. For a while, the inside of the tunnel was bare rock. But rock has a tendency to fall, disrupting train schedules and endangering train crews. Through the years, stonework was added to the entrance. Bricks were laid along the walls, then covered with concrete. A concrete liner covers the ceiling.

To increase the clearance, crews first pump grout behind the concrete-covered walls, then insert long bolts through the sides and the rock behind. Using a diamond tip saw, they cut a notch near the top of the wall. Then the big excavator moves in and begins to chew away the ceiling.

The concrete averages about 2 ft. (0.6 m) thick, Billingsley said. In some places, there’s a 5-ft. (1.5 m) gap between the concrete and the rock above. In others, the concrete liner is tight against the rock. Either way, the machine cuts out room for the double stacked containers, and crews put in 20-ft.-long (6 m) roof bolts, then spray in a new liner of shotcrete.

During the construction, the track is closed for about 10 hours a day. Some sections of the track between Cowan tunnel and the West Virginia-Ohio state line will be closed for more than two more years.

Crews started tearing a higher ceiling in the Cowan tunnel in mid-February. If everything goes as it should, the tunnel will be finished by mid-September. The whole Heartland Corridor project is scheduled to be finished by the middle of 2010.