Trestle Bridge - Geruestbruecke
































Sloping Trestle - Abschuessige Bockbruecke




in March 2020 copied from my thread in LSC
(from march 2014)




i was building a ten foot long trestle.

for the observer standing in front of it, the ground goes up from the left to the right, while the deck of the bridge goes down from the left to the right. (both at 6% grade)
thus the vertical trusses build no right angle with deck or ground. the leftmost trestle is 40cm high (nearly 16"), the rightmost one is 8cm high (about 3").
the distances between trestles are 6" (15cm). that worked fine for me.

My trestle is not very wide. for that, there are fiftyeight point four reasons.

58.4 cm (23") being the avayable space for three paralel tracks of differing and opposing grades. (plus some landscapeing)

for using wooden guard rails the deck would have had to be about two inches wider. (not even to mention spaces for fire barrels)
a two inches wider footing of the bents was simply not possible.

metal guard rails of 332 LGB would have looked too massive for my taste. importing six meters of smaller rail from north america or europe wasn't worth the trouble to me.

a desired sidekick was, that the slim construction results in an enhanced impression of length.

in hindsight, i could/should have made the spaces between the sleepers/ties smaller. (now the spaces equal the width of the sleepers)
on a quickly nailed together jig, i marked the different lengths for the various trestles.
i drew some horizontal marks on the jig. (in my case many, for the many different lengths of bents)
then i pushed the two outer beams against the upper stopper and sawed them off at the mark for the upper horizontal.
after putting the upper horizontal in its place, i pushed all four beams against it, stapled them to the horizontal.
at the desired length i sawed off the beams (all four at once) with an iron saw. (they are long enough to get all four with one cut)

after stapling the footer to the beams, i turnd the whole bent over in the jig (thus confirming it to be simmetrical) then stapled connections from the other side.
at last i nailed the horizontal and diagonal boards to the bent.

no glue involved.

the ties, posts and beams are from cedar. i used 10 by 10 mm (3/8 by 3/8") for the bents (vertical and horizontal) and the boards (2 x 10 mm) (13/32 by 1/16") from pine.
the ties/sleepers are cut to the LGB dimensions.

the posts are connected with cramps (just tackered), the boards are nailed on with shoemaker nails.
staples used are 8mm galvanized hardened steel.
used them for both sides, for the caps and for the footers.
for nails i used soft shoemaker nails. they don't go in straight.thus giving some force against being drawn out.
 


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for the deck of the bridge (road"bed"?), i made another simple jig.
at the head i nailed on a single LGB-tie, on one of the sides i clamped a board as arrestor.
such i could position two ties, fix them with the movable tieweb, nail every second to the rails, and later take out the spaceholder ties.
(the 1 mm thick ruler beside the tieweb became necessary, because the carpenter cut the ties 2 mm too long)
the rails are LGB 5' long profiles.

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the shortest nails, i could get here, are a wee bit too long.
to pinch them off a bit, would have meant pre-drilling and a lot more work. so i choose another way.

after lightly hammer in the nails (the surgical tweezers did prevent a lot of finger-hits) and driving them in, using a setscrew head down and the hammer, i bent the nails sideways over the railfoot with the pincers.

then i helt the pincers from above upon the nailheads and hammering on the grip of the pincers, drove the nails down on the foot of the rail.

in the eyes of many, this will not look nice, but work under the assumption, that on a bigger layout the general impression will supersede details.

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after i leveled the bench more or less, and prolongated it to ten foot, i connected the two 5 foot pieces with LGB fishplates, and screwed the beams to the ties.

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now came the interesting part.
for the trestles to stand straight, when everything is finished, they had to be fixed a 3.5 inclinated to the beams.

my new jig (a board, sawed to the correct angle, and hindered from falling over by blocks clamped to its sides) seemed to give the adequate inclination.
i sawed a little groove as arrestor for the file, filed a little inclination, and was ready to nail the first trestle to the beam.

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as soon, as i had repaired my flexible elongationshaft for drilling, i did continue...

the 6% are tested for my situation and rolling stock. nearly all locos are Stainzes with motorized tenders, drawing five foot of cars. (either five four-wheeled ones, four eight-wheeled cars or combinations of the two kinds)
locos and tenders do get additional weight to four and a half pound each. (my only Bachmann loco died of a broken heart, trying to haul itself and the tender up that grade...)

after predrilling i could easily nail the trestles to the running beams.
i used the same nails for this, that had to double as railspikes.

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to stabilize the trestles, again i use the above mentioned boards.
tiny shoemakernails lightly hammered into the boards, and then driven into the posts not with a hammer, but with a adjustable tweezers, makes for good and stable connections.

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now i just had to play around with the placement of the boards, to find an optical pleasing distribution.

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as one can see above, i was kind of stuck at that moment.
the only word, that came to mind, how the first part looked, was "shitty"

it looked as if the engineer responsable had studied social engineering...

i got something done:
the nastiest part of the project. to get the kerbs more or less similar in inclination.

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looked at under dim light, i was content.

that raises a phylosophical question.
for the famous "10 foot rule" (if it looks acceptable from 10 ft, be content) - how does this apply to 10 ft long objects? at the nearest or at the farthest part of the object?

thanks for all, who councelled me on how to put the boards.
after some tries, i settled for this. the individual boards now are more or less horizontal, while the whole enhances the impression of a steep ramp.

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this is only a staged mock-up.
i was still working on the lowside access and the curve on the upper side still lacked a roadbed. (the roaadbed still awaits to be done - march 2020)

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here comes the last part:

well, the lower part of the bridge is done too.
(i planned it, to be able, to compensate any screw-ups, that my height management of the bridge might have had. it turned out, that everything fits fine)

at the very end of the project i had to screw up! the very last tie did split at screwing it to the beams...

i did, what every second rate wildwest railway would have done - i belted the tie to another one, that i put beside.

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the inspector M. Onkey was convinced bei the engineer (soc.) R. O. Oster that a jumping-up-and-down stability test was not necessary

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the crew placed the last tie

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the president of the Southern & Gulf helt a moving speech to a crowd of onlookers
(well, yes, that area is very scarce populated...)

in his speech he mentioned, that the last spike on this bridge would be driven in by him personally.
(regretfully, we must admit, that he could not fullfill that. of his crew of cowards nobody volunteered to hold the spike for him)

from the following little celebration (no disturbing food, only drinks), we can not offer any pics, because the photographer had problems with his optics...

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