# Cardboard strip question?

Discussion in 'HO Scale Model Trains' started by trainsteve2435, Nov 10, 2006.

1. ### trainsteve2435Member

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Hello once again, I have decided to form my tunnel liner of cardboard strips and hot glue. My question is this.... What is a good safe length to make the cardboard strips in order to ensure i have enough heigth for clearance of cars? I did a test run useing 12" strips, but it wasnt enough clearance on the inside curve to allow a 69' double stack to clear both on the side and heigth. Would 14" - 16" gimme enough? Thanks!
steve
2. ### jasbourreMember

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I din't use cadboard for my tunnel, I made the walls out of styrofoam. Cut the back every inch or so for the curves, turned out nice. I added woaded newspaper arroud, then plaster cloth to finish.
3. ### MasonJarIt's not rocket surgery

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Steve,

If you don't have one, get an NMRA Gauge - it can do all kinds of useful things like checking the gauge of wheels and track, and measuring clearances.

Until then, your best bet would be to experiment...!

Andrew
4. ### Russ BellinisActive Member

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I don't run any double stack cars, so I don't know how tall they are. If you are running track laid on ho scale cork roadbed, you can figur 1/2 inch for the track & roadbed. I would figure a 1/2 circle for the roof of the tunnel. To figure the length you need to form the roof, multiply 3.14 x the diameter to get th circumference of the circle that would form the roof. Divide that number by 2 to get the circumference of the 1/2 circle that forms the tunnel roof. measure the distance from the rails to the top of your double stacks and double it. Add that number to the circumference of the 1/2 circle you got previously and then add 3 inches to the total to account for the roadbed and track and 1 inch left over on each side to glue your tunnel liner cardboard strips down. That should get you close to the length you need for the tunel strips.

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