Pneumatic Tools Help Prevent Open Cutting of Railroad

Near New Albany, Indiana, just across the Ohio River from Louisville, Kentucky, the CSX Transportation railroad rumbles six times daily, hauling freight through the southern Indiana countryside.

Six times a day, the railroad depends on the track to provide an unyielding, stable foundation for the weight of its 50-mph diesel-locomotive-driven revenue producer. Six times a day, 365 days a year, the rail bed must not erode, and the embankments must remain rock solid. Stone box culverts created 150 years ago - and the updated corrugated pipe brethren that followed them 70 years later - channeled the creek and field run-off water under and through the rail bed of one five-mile stretch of this railroad as it runs north from New Albany to Salem, Indiana. The years took their toll however, and the rusted corrugated pipe and deteriorated stone culverts began to collapse, requiring replacement to avoid threat of erosion to the embankment and the rail bed. Getting the job done - with minimal disruption to train traffic - was the challenge facing CSX Transportation.

CSX Transportation Supervisor of Bridges, Craig S. Guth, P.E., summed up the problem facing the railroad, "The concerns of CSX Transportation while planning this drainage replacement project were many." Safety concerns with settlement, quality concerns about the track and its rail bed, and revenue-losing disruptions to train traffic were high on the priority list.

There were five drainage culverts scheduled for replacement out of the 1,100 in the 80 miles that separate Louisville, Kentucky, and Bedford, Indiana. Originally, the railroad planners thought that they would be forced to bid the job on an open-cut basis and demand from the contractor that any one of the new pipes be installed in a single day, with the trench backfilled and compacted, and the track replaced by nightfall so trains could be routed to run the track the same evening.

This original plan faced potential scheduling nightmares. So when Len Liotti, owner of Midwest Mole, Inc., suggested using pipe ramming with a large HammerHead Mole to push in the new casing and install the new drainage pipe without disrupting train traffic, railroad officials were all ears.

"Pipe ramming was the superior method for the replacement of these drainage pipes," said Guth. "Not only were we able to keep train traffic moving without any disruption, but we had no fear of loss of integrity to the rail bed and embankment. We didn't have to worry about creating any voids during the installation - since we were driving a solid steel pipe - or any post-project settlement. Despite the higher up-front costs, it accomplished what no other method could have."

Liotti and his crews know about putting holes in the ground. They've used a variety of tunneling methods for the past 16 years, working with auger-boring machines, micro-tunneling, hand tunneling and, more recently, pneumatic pipe rammers. According to Liotti, pipe ramming has become his preferred method for culvert replacement work. "When you have soil conditions like those underneath these rail beds including: like boulders, cobble, sand and gravel, rip rap and rail ties - pipe ramming with the large pneumatic tools is much better than traditional auger boring. When we ram, the lead-reinforced pipe edge shears the ties and cuts and breaks up the rocks. With auger boring, not only would the boulders cause the pipe to go off line and grade, but the rocks would get stuck in the flighting."

Two of the five culvert replacements demonstrated the reason why Midwest Mole, Inc. employed pipe ramming. On the first of the replacements, the crew installed 50 feet of 36-inch pipe. Rather than punch a new hole through the rail bed, the crew went through the existing culvert, swallowing up the existing deteriorated 24-inch corrugated pipe. David Miller, Midwest Mole's crew foreman, described the installation. "Because we took the casing over the existing corrugated pipe, we were able to follow established drainage patterns and didn't have to fill in the old line with grout and move over for a whole new line. During the ramming part of the job, the 16-inch HammerHead Mole hammered the 50 feet in a half hour, chewing right through old rail ties. If we had been using any other method, those rail ties would have stopped us cold."

The process Midwest Mole's crew used entailed getting access to adjacent property and moving its excavation equipment and the rammers to the site. After excavating the launch pit, they leveled it and installed their auger-boring unit track and set it on their desired grade. They had their pipe contractor fabricate a reinforced soil shoe on the lead pipe so that they had quarter-inch clearance from the bore wall on the outside of the pipe and a quarter-inch clearance from the spoil accumulation on the inside of the pipe. Because of the short length of the bore, Miller and his crew did not add lubrication for the ramming. After ramming, they cleaned out the spoil using their auger flighting. All the restoration work was completed before the crew moved on to the next culvert replacement.

As the crew worked, the trains ran uninterrupted. The crew did stop the pneumatic tool ramming once, however, so that the vibration of a passing train would not shake the track.

Another casing rammed in was 48-inches in diameter in order to concentrically swallow up the deteriorated 36-inch corrugated pipe. Midwest Mole brought in the 23-inch HammerHead Mole to hammer the half-inch wall pipe through the 50 feet of Indiana limestone to move the new drainage pipe through the existing culvert.

With its 48-inch adapter ring and 24-inch collets to accommodate the tool, the HammerHead was lowered into the launch pit some 20 feet below the track surface. The tool was started up; it taper-locked itself into the collets and the push was on.

"If we had not pipe-rammed this culvert, we would have had to open a new culvert, direct the creek away from the original channel and turn the creek on the other side another 90 degrees so they would meet up," said Liotti. "By hammering with the pneumatic tool, we saved a lot of time and tons of rip rap that we would have had to restore the site with." The 23-inch HammerHead pounded the 50 feet of 48-inch diameter pipe in under 90 minutes, with most of the time spent during the last 12 feet of the push. When the crew cleaned out the limestone spoil, they saw the aggressive chipping accomplished by the tool.

"With pipe ramming we had no interruption of service," said Guth. "So we know this is the way to go on these culvert replacements. There was no appearance of any settlement or any concern about rail bed or track integrity."