WELCH, W.Va. (July 30, 2009) — As workers a century ago built the rail line traversing western Virginia and southern West Virginia, they had to pass through the Appalachian Mountains. The tunnels through the mountains were engineering marvels when they opened, given that they were built without the use of modern-day boring machines.
But, over the last century, the size of trains has increased, which now poses a bit of a problem for railroads operating trains over old routes with tight clearances. Norfolk Southern’s Heartland Corridor, a vital line that connects the port of Hampton Roads, Va., and Chicago, is one such example.
As part of a three-year project, Norfolk Southern, which operates 21,500 miles of track in 22 eastern states, is expanding 28 tunnels along the Heartland Corridor by adding up to two feet of headroom, which will allow larger trains — and thereby more cargo — to use the route and cut roughly 200 miles off their trip. The $150 million project, which began in 2008, is slated for completion in 2010.
Norfolk Southern hired three contractors to complete the project — San Leandro, Calif.-based Johnson Western Gunite Co.; Tillamook, Ore.-based LRL Construction Co.; and Nicholasville, Ky.-based R.J. Corman Railroad Co. As the material supplier selected for the tunnel work, The QUIKRETE Companies delivered QUIKRETE Core Fill Grout, QUIKRETE Non-Shrink Precision Grout and QUIKRETE Fiber-Reinforced Shotcrete MS to these contractors.
For the project, Norfolk Southern reroutes as many trains as possible to allow for the construction, but cannot completely shutter the line during the tunnel work. So, crews start their work on Saturday and must be finished on Wednesday, with scheduled work times of 2 a.m. to 12 p.m. each of these days, at which time the rail line resumes its normal operations.
“The challenge with this project is that Norfolk Southern cannot close the tunnels to all rail traffic because this is such an important route for freight movement,” said Charles Davis, QUIKRETE plant manager at the company�s Pounding Mill, Va., location. “That means workers have a limited window in which to work. As the material supplier, we have to be diligent to ensure that our customers have the products they need when they need them; otherwise, the entire project would be slowed.”
Because of its vast distribution network, The QUIKRETE Companies is able to successfully supply contractors with the materials — working overtime and on weekends as needed to make sure any and all deadlines are met. The company’s Pounding Mill plant exclusively serves the tunnel project and hasn’t missed a delivery deadline yet.
Between April 2008 and the end of last year, The QUIKRETE Companies supplied 16,950 bags of QUIKRETE Core Fill Grout, QUIKRETE Non-Shrink Precision Grout and QUIKRETE Fiber-Reinforced Shotcrete MS to the project’s contractors. All of the products were in 3,000-pound bulk bags, except for the QUIKRETE Non-Shrink Precision Grout, which was supplied in 50-pound bags.
Over the last three decades, freight traffic on railroads nationwide has increased, and railroads have turned to double-stack trains — or cars that allow intermodal containers to be stacked one on top of another — to boost the amount of goods each train hauls. The intermodal containers are used worldwide on ships, trucks and trains to carry a number of products.
Modern-day stack trains require tunnels to be at least 20 feet, 9 inches tall. Because of the small tunnels through the Appalachian Mountains, Norfolk Southern’s large intermodal trains make the trip from Hampton Roads, Va., to Chicago via Harrisburg, Pa., or Knoxville, Tenn.
Along the Heartland Corridor, Norfolk Southern has employed a number of methods to increase the clearance, including raising the roof and lowering the track. To expand the tunnels, workers must also transform the passageways’ corners from rounded to squared, which allows the taller trains to pass.
The railroad even removed the roof from one of the 28 under construction as part of a 174 foot-long “daylighting” of a tunnel. The tunnels, which range in length from 174 feet to 3,302 feet long, were built with arched roofs and rounded corners.
The QUIKRETE Companies is involved in 27 of the tunnel expansions — eight that require the linear notch work to square the edges, 18 that require complete roof replacements and the one “daylighting” project.
As part of the tunnel expansions that require linear notch work and roof replacements, crews bore holes every four feet, which allows them to fill any voids behind the tunnel ceiling with QUIKRETE Core Fill Grout. Workers then install 18-foot-long roof anchors to secure the tunnel ceiling to the mountain above; they complete the process by applying QUIKRETE Non-Shrink Precision Grout to fill in the holes.
While expanding the tunnels to accommodate larger trains is a primary objective, it is just one of the goals of the multi-year project. The railroad wants to ensure that the tunnels are stabilized and safe for the next century.
Before workers can square the corners, they need to ensure that the tunnels’ roofs are solid. They start this process by drilling a hole in the ceiling to check the canopy. If workers find a void behind the canopy, they pump grout into the void to create a solid ceiling. Since workers need to ensure that the roof is solid, they fill holes in areas that are later to be squared.
QUIKRETE Core Fill Grout is a pre-blended product requiring only the addition of water to obtain flowable properties and high strengths.
Using shotcrete combines the process of applying cement to the tunnel walls and packing it down. Spraying the shotcrete also eliminates the need for forming and provides an extremely dense (9,000 psi) and high-strength concrete tunnel lining.
“It’s important that these tunnels have a solid canopy in place before workers start squaring the edges,” Davis said. “It’s hard to know exactly what we are up against until workers start testing the canopy and pumping grout into the voids. For one void, workers pumped 780 bags of grout into the massive hole.”
While modern technology has shouldered the load in bringing the corridor into 21st century compliance, there’s no shortage of respect and admiration amongst today’s workers for those who forged the line.
“The workers who built these tunnels a century ago didn’t have the luxury of using the technology that we have available today,” Davis added. “But the fact that they build these tunnels through such irregular topography is a testament to their skill and dedication. We want to preserve these tunnels not just for the next 100 years, but for as long as the railroad uses them.”
The tunnel project was recently awarded “The Outstanding Underground Project” by the American Shotcrete Association.
