History Of The Railroad Article 15

Tunnels Part 1

     So far, we have looked at the evolution of the rail, the roadbed, ties and spikes. Also, surveying the road, laying the track and building the different types of bridges.

     The one aspect we have not looked at yet is the most time-consuming, hardest to build and contributed to the most loss of life in the building of the railroad. That's the boring of the tunnel. Tunnels that were between a few feet and 10 miles long.

     They took from months to years and one tunnel took over a century. They were the most expensive to build and to maintain.

     Tunnels were all of this, but it would have been impossible to cross the mountain ranges of the Sierra and Rocky’s without boring a tunnel.

     The importance of the tunnels was to be able to maintain a grade at not more than 2%. This was needed to run the railroad efficiently enough, transporting people and freight and maintain a profit.

     A 2% grade does not exceed 2 feet of elevation for every 100 feet travelled. ²

     You can track railroad bridges back to industries beginning in the mid-19th century. The early bridges were built of stone. Some of these engineering marvels can still be found in the eastern United States and are still used today.

The Thomas Viaduct of the Baltimore & Ohio Railroad, Spanning Patapsco

River, Elkridge, Howard County, MD Closer in aerial view looking southeast.

Jack Boucher, Public domain, via Wikimedia Commons

     Before we get into the tunnel so too far, we need to mention that at the peak of railroad, there were 150,000 miles of railway in the United States alone. So that’s 300,000 miles of rail. To put it in perspective, it was enough to make 12 steel girdles for every mile of earth's circumference.

     It's hard to imagine that the small, mushrooms shape of steel

can't support the train

     This year, in 2024, the Union Pacific “Big Boy” came to Bismarck, Missouri on its Heartland American Tour. The big boy and its tender, at full capacity weighs 1,208,000 pounds.

     The tender holds 25,000 gallons of water, and it held 28 tons of coal, which it used as fuel until 2019. It was then converted to burn No. 5 fuel oil. It has the capacity of 6,500 gallons of fuel oil.

     The “Big Boy” had been built to pull the freight trains over the mountain regions of Utah, Wyoming and Colorado. In fact, the 28 tons of coal, that was the capacity of its tender was enough for the “Big Boy”, pulling a 3600-ton train between Ogden and Echo, Utah, 55 mountain miles. ³

     With all that said, it is amazing that this tiny, in comparison, two rails of steel, being held by 12,800 spikes per mile of track, could hold that much weight being transported on it. ¹ The load is enormous, but the rails bear the burden.

     When constructing the line through the mountainous region, when reaching the summit, the grade must be kept as light as possible. Plus, it may never exceed the maximum prescribe grade of 2%.

      Also, curves must have a gentle radius. Lines must be long at times to overcome the vertical height of the line.

     When the canyon or ravine directly crosses the line, a bridge or viaduct must be built to expand it.

     Without tunnels, it would have been impossible to cross the mountainous passes. Plus, to do it at a grade where the locomotive could operate efficiently enough to make it profitable.

Western portal of the Staple Bend Tunnel

Coasterlover1994, CC BY-SA 4.0

<https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

     The first railroad tunnel in the United States was the Staple Bend Tunnel, located near Johnston, Pennsylvania.

     Built by the Allegheny, Portage railroad in 1831, it was completed in 1834 and only remained in operation into the 1850’s. ²

     The Staple Bend Tunnel, like most of the early tunnels, were costly and labor intensive. Safety wise, they were unregulated, and the loss of life was well above today's numbers. This was due to how they had to blast earth and rock to burrow through the mountains. ⁵

Interior of the Staple Bend Tunnel, looking west

Coasterlover1994, CC BY-SA 4.0 <https://creativecommons.org/

licenses/by-as/4.0>, via Wikimedia Commons

     Dynamite and nitroglycerin had not been invented yet. Black powder, which was highly unstable was what was being used. To split and crush the rock, boring through the mountains

     A hole would be drilled into the rock by using a two-foot handheld drill bit, which looks like a chisel. One man would hold it in place while the other would strike it with a sledgehammer. Then the one holding the drill bit would turn it a quarter turn and then the hammer would ring again, followed by another turn. So, the process would go on until they were 18 inches in depth. They would drill three or four of these holes. Then they would pack them full of black powder and a blasting cap, lite it and run like mad for cover. They would progress about a foot a day using this process. ⁴  

     So were the difficulties of boring through the rock. If that was not enough, a railroad in Peru as an example of the difficulties of building a line in the mountainous regions. As a tunnel was being built it reached narrow gorge.  A truss bridge was placed across it. The tunnel then continued into the opposite rock face on the other side.

     The bridge was 575 feet long, consisting of four spans, supported by iron towers. The center tower is 252 feet high. They had constructed the bridge above ground and then lowered it in to place by two wire ropes cables that were suspended over the ravine from temporary towers that had been set up.