Ok, so I have a 24 ft testle and the bents will be 6 " apart. 6" is appropriate isn’t it ? That would be 12 Ft. apart
That would give me 48 bent,The rise is 5" total so what increments do I use for each bent? Never tried to figure this stuff out before, know how to make bents though !
Thanks Again from the mathmaticley challenged !
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.
Make all the bents the same size and wack the bottoms off as you rise uphill. 
j
Bryan Johnson said:Bryan,
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.
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.
John Bouck said:Be careful John, I just might be dumb enough to try that. Then I can tell everyone it is a John Bouck design:) :)
Make all the bents the same size and wack the bottoms off as you rise uphill. :) :) j
Bob Zajicek said:Bryan Johnson said:Bryan,
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.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.
Well , how everyone else does it in the UK is refer logically to slopes as 1in 4 ,for example , this means up 1 along 4,or goes up 1 for every 4 travelled . Much simpler than percent. There is a quick conversion for percent to #in# , I believe 1in 20 to be 5percent -achieved by dividing 20 in to a hundred .
So correct me if I’m wrong , and I might be .
I just say steep , bloody steep , and bugger me ! Beyond that is engage low transfer .
Mike
OK, Instead of whacking, just bury the long ones as you go downhill.
<Am I making this too complicated ?>
Uh, prolly just a bit.
whackin’ or buryin’
Don’t forget the top deck of your trestle as you plan for height. On top of your bents will be long stringers, usually the same dimensional lumber of your trestle bent legs (1/2 x 1/2–or whatever you are using for material.)
j
Bryan Johnson said:Bryan,
[ Or I could just make the trestle and adjust the ground for it. Am I making this too complicated ? How does everyone else do it.
I can’t really tell if you’re over complicating this or not because I’m not familiar with the details of your proposed installation. Is the 5†rise over 24’ something that can be adjusted or is it a fixed amount? Is it a straight section or curved? What are you setting the bents on, concrete, dirt or what exactly?
There are numerous methods of trestle installation and I think if more details of yours were known, the responses could be more accurately tailored to the situation you’re facing. FWIW.
Just being helpful here .
Get a 24 foot board and lay it where the trassle’s a goin’ . Then whack some posts in the ground . Saw ‘em off same height as board .
Or use UK measuring technique , it’s much easier .
If’n ya got a 3/4" rise every 4 ft., stick some posts in every 4’ ,making each 3/4 longer than the other . Make sure ya do that goin’uphill , now .
Now lay a stiff board along the top of each 4’gap , and welt in a few posts between ,making them the same height as the board . Don’t want posts ? Measure the things then . Hang a tape from the board .
Mike
Mike Morgan said:Thats a great idea Mike nice and simple . like me. Your starting to get a little American accent there, except for welt you thru in. What is the uk measuring technique ?
Just being helpful here . Get a 24 foot board and lay it where the trassle's a goin' . Then whack some posts in the ground . Saw 'em off same height as board . Or use UK measuring technique , it's much easier . If'n ya got a 3/4" rise every 4 ft., stick some posts in every 4' ,making each 3/4 longer than the other . Make sure ya do that goin'uphill , now . Now lay a stiff board along the top of each 4'gap , and welt in a few posts between ,making them the same height as the board . Don't want posts ? Measure the things then . Hang a tape from the board . Mike
Bob Zajicek said:Bryan Johnson said:Bryan,
[ Or I could just make the trestle and adjust the ground for it. Am I making this too complicated ? How does everyone else do it.I can’t really tell if you’re over complicating this or not because I’m not familiar with the details of your proposed installation. Is the 5†rise over 24’ something that can be adjusted or is it a fixed amount? Is it a straight section or curved? What are you setting the bents on, concrete, dirt or what exactly?
There are numerous methods of trestle installation and I think if more details of yours were known, the responses could be more accurately tailored to the situation you’re facing. FWIW.
I was planning on just gravel underneath the trestle. Hope that helps to understand better.
Thanks
Bryan ,
The UK technique is just as I described , "welt " being a midlands expression for knock the thing in a bit hard . Actually , you will see the technique used on building projects. See those posts sticking out the ground with a flat piece on top ? That’s the grade the bulldozer has to level to . You will see they even put them in holes when the grade goes below existing ground . That’s how they get the ramps on motorways , some of the bulldozers have laser sighting now , but the site is still pegged out for the lasers to work with .
So , remember , grades are 100 forward , one up . 50 forward , 1/2 up , 25forward ,1/4 up all equal 1%or
1in100 .
I just checked an old photo I have of the navvies wheelbarrow tipping an embankment on Brunel’s railway . The wood posts are quite evident .
Mike
ps it works on curves as well , a curve is treated as a series of short straights
Thanks again Mike !
…we just had a trestle burn on the IPP&W today…made for a neat experience…
That’s not what Guy Fawkes said when they threatened to burn him at the stake ,or was it as a steak ?
Guy Fawkes , who he ? The first bloke to treat politicians correctly , or try to . He attempted to blow up the Houses of Parliament , before America was born . Even though he had the right idea , they hung drew and quartered him anyway . Shame , my kind of man .
Anyway , howja set a trestle afire ? We need to know . I know one thing ,YOU didn’t spill whusky and set it .
And given the above erudite explanation of rising measurements , you can build a better one .
Mike