What is the grade I should use building trestles ? Is 1/4" per ft. going to be to much in HO scale?
q2w - Welcome to trains.com! [C):-)]
That works out to about a 2% grade, which would be OK.
(2% = 2 inches rise in every 100 inches, 1 in. every 50 in., 1/2 in. every 25 in., and 1/4 in. every 12.5 in.)
Welcome.
Depending on what you’re modeling, you could go even more. As I recall, the Saluda grade is around 5%. Of course most modern mainlines like them less than 2%.
Richard
Hi q2w and[#welcome]
1/4 inch per foot is 2%. That’s the max I like to go. If you have the room or a bit bigger layout planned consider changing the degree of climb as you go. In the pic below the spline roadbed changes the degree of climb as it goes up. It makes for a less stamped out, more natural flow look on the layout. The same also applies for curves. A curve with a changing radius looks better than a stamped out 180 degree turn. As long as you don’t go below your minimum radius it can add to visual appeal.
Brent[C):-)]
The maximum grade for a trestle is whatever grade the track crossing it needs to have.
The Mount Washinton Cog Railway is built on trestlework, some of it in the 70% range (37 degrees from horizontal!)
1:48 is less than Congress specified as maximum for land grant railways in 1862. Their requirement was the maximum used by the Baltimore and Ohio - 2.2%
My own work calls for 2.5% and 4%, but my bridges are steel - deck girders on masonry piers.
The only requirement is that piers, and trestle bents, have to be vertical.
Chuck (Modeling Central Japan in September, 1964)
On the Verazano Narrows Bridge the tops of the towers are further apart than the bases of the towers.
Each tower is perfectly vertical, but the earth is curved.
ROAR