Bryan Johnson said:
Ok according to my math ,I have a 2.88 % grade and have a 3/4 " rise every 4 ' . Does that sound right ? After that My mind flakes out.
Bryan,
The short answer is just 5†divided by 48 bents = .104†per bent. … a tad over 3/32†each. This is cumulative in that the first bent is + .104, the 2nd bent is + .208, 3rd is + .312, etc. through all 48.
To figure the grade %, first convert your trestle length of 24 feet to inches by multiplying 24’ X 12â€= 288â€. Now divide the 5†rise by the 288†total length. This gives you a grade percent of 1.736%, well within accepted practice for GRRs which is typically 2% to 2.5%.
Having said all that, block up your roadbed temporarily over your 24’ total length. When you’ve got it leveled out OK, go back and trim your trestle bents to fit as needed, replacing the temporary supports with the bents. HTH and good luck.