Pulling for you

Wheel loaders help keep Alaska tunnel clear, even if it means retrieving a stalled vehicle

Tunnels Article April 03, 2001
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A 2.5-mile highway tunnel in Anchorage linking south-central Alaska to the port at Whittier on Prince William Sound through the Maynard Mountain is the longest highway tunnel in the country. Completed in mid-June 2000, it can accommodate 800 vehicles an hour.

Built in 1943 by the Department of Defense, the Anton Anderson Memorial Tunnel was used only by the Alaska Railroad. Trucks and automobiles traveling on the Portage Glacier Highway had to stop at the tunnel and then be transported on flat cars, while their drivers and passengers stayed in their vehicles.

With increasing demand for access to Prince William Sound, the Alaska Department of Transportation and Public Facilities (Alaska DOT & PF) opted to transform the railroad tunnel into a combination one-lane highway and railroad tunnel. The drive surface of the tunnel was made even with the tracks, and motor vehicles and trains take turns traveling through the tunnel. To keep the tunnel clear of snow, debris and disabled cars, the Alaska DOT & PF turned to Case 921C wheel loaders.

Snow, rock and car removal

Because the tunnel has only one lane, vehicles line up in staging areas at either end and proceed through in one direction or the other in 15-minute intervals. The tunnel is closed to vehicular traffic when a train is coming through.

To make sure both ends of the tunnel are passable during the state’s snow season, Alaska DOT & PF looked for a piece of equipment that could clear snow quickly in fairly tight spaces. This equipment also had to be able to clear occasional rock slides off the road. But there was still one more important job for the equipment if it ever became necessary.

The tunnel provides eight turnout spaces for disabled vehicles, and a method was needed to get these vehicles out of the tunnel. Whatever equipment was ordered for snow and rock removal also had to have enough power to lift the end of a truck, bus or car and successfully pull it out of the tunnel.

"The specs called for the equipment to have a UV blade for removal of snow at the tunnel’s entrance and exit," said Earl Lackey, sales manager for Yukon Equipment, the Case dealership in Anchorage. "It also had to have a quick coupler to easily swap-out attachments, such as a bucket. The Case 921C was the answer. It had a blade attachment that swiveled for snow removal, a quick-coupler to change to a bucket and the weight, lift capacity and hydraulics called for in the state’s specs."

Satisfied that the Case wheel loader could do the job, the Alaska DOT & PF ordered two of them, one for each end of the tunnel.

The 921Cs are equipped with forks modified by Alaska DOT & PF engineers that allow them to hook onto an axle, lift up the front or back end of a vehicle and pull it out. The maximum lift capacity of these units is 46,109 lb.

"But we’ll use these units for most everything," said Greg Hall, facility manager. "We’ve already put them to work cleaning up some rock slides we had near the tunnel."

He said these blade-mounted units also come in handy when removing not just inches of snow, but snowdrifts.

"With winds reaching up to 150 mph, we can get drifts as high as 5 ft in less than an hour’s time," he said. "We need something with muscle to take these down quickly.

"In addition to the wind and snow, temperatures can get down to 40û below zero. If a machine isn’t built to handle these conditions, it’s not much use to us," said Hall.

Detecting movement

Hall is a retired Air Force master sergeant and a Desert Storm veteran whose specialty in the service was in command-and-control-center operations. As facility manager, this job seemed to be made for him.

The tunnel has a control center that houses a computer-controlled Tunnel Control System (TCS) and Train Signal System that allow the trains and cars to safely take turns using the tunnel. The TCS also monitors vehicle movement within the tunnel. If a car, truck or bus stops for any reason, the detection equipment will alert the tunnel-control operator, direct the video cameras to display that area of the tunnel and shut the appropriate gates. At that point, one or the other of the 921Cs will go in, if necessary, and pull the vehicle out.

Manufactured air force

"We have layer upon layer of safety controls built into this tunnel," Hall said. For example, another safety device is the use of fans to control the wind direction in the tunnel. In the event of fire, four 300-hp portal fans will blow smoke and fumes away from any vehicles stopped in the tunnel. During normal operations, six 75-hp jet fans are used for ventilation.

Fortunately, to date, the Case wheel loaders have not been called upon for any rescue operations, but because of their versatility, Hall will put them to good use when they’re not pulling out vehicles.

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