By Rick Henderson LSOL.com Associate Editor

Author  Bio Track laying across a bridge or trestle follows the same principle as laying on a ballasted roadbed.

Crossing Bridges

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Track laying across a bridge or trestle follows the same principle as laying on a ballasted roadbed. Keep it level and keep curves constant and centered. On this bridge, 2x2 ties were used in the making of the track panels and the track was laid on a 4' wide, 9' tall deck bridge.

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The rail has to make the transition from the 2x2 bridge ties to the 2x4 regular panel ties exactly. Also on a bridge you have guardrails, usually two sets. The inner set is simply an additional set of rails laid in between the regular track at such a spacing to allow a derailed engine or car wheels to be caught between the running rail and the inner guardrail and travel along on the ties. The ends of these guard rails are tapered to the center of the track in case a car is already derailed as it approaches the bridge, thus bringing the car more to the center of the track and allowing it to actually cross the bridge without causing damage to the bridge or going over the edge of the bridge.

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The guardrails need to be kept a constant distance apart across the bridge and a simple wooden guardrail gauge will make this job easy. You still need rail joiners on the inner guardrails at each joint, however the inner rails do not need to be screwed to every tie. A train should never attempt to cross a bridge until the inner guardrails are installed. They do work well.

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The outer guardrails work to keep cars on the bridge that somehow may completely jump the inner guardrail. They need to be higher than the rail so that the car trucks cannot easily climb over them. We use 2x2's on ours attached to the end of each tie. The second function of the outer guardrails is holding the ties in place.

Special Needs Of Large Scale Track

The most obvious issue in a riding scale is weight. The lightest cars you find are easily over 70 pounds. A set of trucks alone can weigh 40 pounds. A large steam engine can weigh up to 3000 pounds. Then you add people of various weights.

The track laying described above will handle these weights easily, but we have to get the trains to the track and in the case of live steam engines, you have to constantly tend to them.

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A loading area and steaming bays require special track work. It is all elevated so that it is easy to roll it out of your trailers or vehicles and to work on your equipment. This club has several sections of elevated tracks to prep the steam engines for running. Once they are ready for the mainline they are rolled onto a transfer table which is then aligned with an outbound track, headed for the main line. All of this elevated track is actually steel parts, usually 1x2, welded together at the proper gauge and supported by 6x6 wood posts.

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An elevated turntable here is actually between the loading area and the steaming area; in the event the engine comes off its transport vehicle in the wrong direction.

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A ground level turntable is also needed to sometimes turn diesels and cars after they are unloaded, or to be reloaded. Often equipment can only load in one direction into transport vehicles; usually it is the opposite direction the layout operates.

Special Situations
Turnouts have little construction difference in 7 1/2" scale from other scales. Controlling them when your riding a train however can be problematic. When an engineer is approaching a turnout that must be thrown for him, he does not want to stop his train, get off and leave it with passengers aboard and walk up to throw a turnout.

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This bridge is a major junction at this club's site with equal traffic going off in both directions. They have added a signal to show approaching engineers, which way the turnout is aligned, on the other side of the bridge. When the electric throw motor is in operation, engineers reach over to the left and push a button on the outside of the bridge frame. The turnout throws; the signal changes and the train may proceed.

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In the event the electricity is not on for this turnout, engineers may throw the turnout manually without getting off the train and before they get to it. Through a series of rods, and universal joints, this simple ground throw controls the points of the turnout on the other side of the bridge. They use this same system in several locations on this railroad.

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This shows the offset controlling rod on the outside of the bridge frame controlling the point throw rod.

Keep It Simple
One hint, don't do everything to the minimum possible. Successful track planning should include establishing standards, which will handle any and all equipment planning on using the railroad. Use as wide a radius as practical and use the minimum radius only where absolutely necessary. Curves create drag on trains and make the engine work harder. Sharp curves create more drag.

Grades are often more of a problem than curves. A 2% grade may not sound like much but it can put a real strain on a train. Plan to keep the grade below 1 1/2 degrees if at all possible. It is best to actually survey the area where the track will go. If you are going to rise 2' in 200' then spread the rise out over the entire length so you have a constant 1% grade. If you go up the 2' in less space you are making the engine work harder.

And when you combine a sharp curve with a steep grade you are likely actually reducing the acceptable standards below your minimums. Avoid this in your planning.

Track laying in 7 1/2" gauge is not simple so take your time, think it through, plan it out, survey as you go and take your time. All of these steps will make riding the rails later more enjoyable.

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