Wood Trestles in the Modern Age of Railroading

[Ted Marshall]

It would be interesting to see recent photos of wood trestles in use. If anybody has any, please share. If anyone can point me to a recent back issue of Trains that would be great too.

Thanks

[dldance]

Until the causeway was built in the 1950's the Great Salt Lake was crossed by SP on a wooden double track trestle (with a station in the middle).  The pilings were driven by barge mounted pile drivers with nearly 20 working at the same time.  If a piling when in full length without meeting sufficient resistance - the another piling was strapped to the top of it and the two were pounded to resistance.  In a few places, the soft mud at lake bottom took a stack of three pilings.  Some of these pilings are being recovered now and Golden Spike will use some to rebuild a small trestle. 

Since most trestles used standard dimensions, many trestles were prefabricated and then assembled in place.  Union Pacific used this method on the 1869 transcontinental.  The timbers were from Michigan and the trestles were prefabbed in Chicago.

It took a lot of hand labor to build a trestle - even a small one.  A typical bridge building crew would have several hundred men.  Holes were drilled with hand augers, timbers were cut with two man cross cut timber saws, final shaping was done with an adze.  If the pilings were driven, then the pile driver could also serve as the crane for lifting the other timbers in place.  But not all pilings were driven.  Some were just set in place on a horizontal timber set in the ground.  The exact approach depended on the subsurface - whether rock or soil.

dd

dd -- you're correctly alluding the two basic types of timber trestles, pile and frame.  Pile trestles consist of piles driven to resistance, cropped and capped, and sway braces, cross braces, and girts added as required.  Frame trestles rest on a mud sill that may rest on piles, concrete spread footings, or directly on the ground surface if it of sufficient bearing capacity (like rock).  Each bent from sill to cap is a separate element, stacked up to the appropriate height.  Steel drift pins set vertically tie together each vertical member, from the top of one to the cap, and through the cap into the base of the next.  This kept the bent veticals from skidding out under load.

Generally the timbers were precut, as you pointed out, and shipped to the site where the bents could either be erected one piece at a time, or sometimes as entire panels preassembled on the ground beneath their final location, stood up, and hoisted into place.

RWM

Thanks for the clarification.  I should have opened my bridge text.  All I learned in school were concrete and steel.  I am learning wood by getting slivers under the fingernails. I am helping Golden Spike stabilize and restore a 45 foot trestle built on a standard SP design.  I do think this particular trestle has been rebuilt at least once because the main beams are 12" X 18".  But these have been neatly trimmed with an adze to 12"X16" at the piling caps.

Golden Spike has a 1/4 mile section of ROW that has structures spanning 100 years of civil engineering - there is the original 1869 rock culvert, a 1901 timber pile trestle, a 1930's timber pile trestle, and a 1960's steel culvert with railroad tie end wings.  We have photos of the 1869 timber frame trestle but that was only used for a few years and then replaced by a fill.

dd 

[Railway Man]

Until the causeway was built in the 1950's the Great Salt Lake was crossed by SP on a wooden double track trestle (with a station in the middle).  The pilings were driven by barge mounted pile drivers with nearly 20 working at the same time.  If a piling when in full length without meeting sufficient resistance - the another piling was strapped to the top of it and the two were pounded to resistance.  In a few places, the soft mud at lake bottom took a stack of three pilings.  Some of these pilings are being recovered now and Golden Spike will use some to rebuild a small trestle. 

Since most trestles used standard dimensions, many trestles were prefabricated and then assembled in place.  Union Pacific used this method on the 1869 transcontinental.  The timbers were from Michigan and the trestles were prefabbed in Chicago.

It took a lot of hand labor to build a trestle - even a small one.  A typical bridge building crew would have several hundred men.  Holes were drilled with hand augers, timbers were cut with two man cross cut timber saws, final shaping was done with an adze.  If the pilings were driven, then the pile driver could also serve as the crane for lifting the other timbers in place.  But not all pilings were driven.  Some were just set in place on a horizontal timber set in the ground.  The exact approach depended on the subsurface - whether rock or soil.

dd

dd -- you're correctly alluding the two basic types of timber trestles, pile and frame.  Pile trestles consist of piles driven to resistance, cropped and capped, and sway braces, cross braces, and girts added as required.  Frame trestles rest on a mud sill that may rest on piles, concrete spread footings, or directly on the ground surface if it of sufficient bearing capacity (like rock).  Each bent from sill to cap is a separate element, stacked up to the appropriate height.  Steel drift pins set vertically tie together each vertical member, from the top of one to the cap, and through the cap into the base of the next.  This kept the bent veticals from skidding out under load.

Generally the timbers were precut, as you pointed out, and shipped to the site where the bents could either be erected one piece at a time, or sometimes as entire panels preassembled on the ground beneath their final location, stood up, and hoisted into place.

RWM

[Modelcar]

....And the ex-SP unit that burnt was replaced in what seemed to be record time frame....!

[andrewjonathon]

There is a great book called Last Train to Paradise by Les Standiford that discusses what it took to build railroads a hundred years ago. This book specifically tells the story of the railroad Henry Flagler built to Key West from Miami. It is not really an engineering book but it is a great read. I was left shaking my head in disbelief at what they went through. I would highly recommend it.

[SactoGuy188]

Well, we used to have a really long wooden trestle just north of the American River on the ex-SP mainline between downtown Sacramento and Roseville, CA. But alas, a big fire last year completely wiped out the trestle, and was replaced by a dual-track steel trestle.

[dldance]

Until the causeway was built in the 1950's the Great Salt Lake was crossed by SP on a wooden double track trestle (with a station in the middle).  The pilings were driven by barge mounted pile drivers with nearly 20 working at the same time.  If a piling when in full length without meeting sufficient resistance - the another piling was strapped to the top of it and the two were pounded to resistance.  In a few places, the soft mud at lake bottom took a stack of three pilings.  Some of these pilings are being recovered now and Golden Spike will use some to rebuild a small trestle. 

Since most trestles used standard dimensions, many trestles were prefabricated and then assembled in place.  Union Pacific used this method on the 1869 transcontinental.  The timbers were from Michigan and the trestles were prefabbed in Chicago.

It took a lot of hand labor to build a trestle - even a small one.  A typical bridge building crew would have several hundred men.  Holes were drilled with hand augers, timbers were cut with two man cross cut timber saws, final shaping was done with an adze.  If the pilings were driven, then the pile driver could also serve as the crane for lifting the other timbers in place.  But not all pilings were driven.  Some were just set in place on a horizontal timber set in the ground.  The exact approach depended on the subsurface - whether rock or soil.

dd

[williamsb]

CN has a line northwest of Edmonton called the Sangudo Sub that has some large wood trestles on it. I believe it has regular trains and unit trains of sulphur. There are 3 large bridges in about 7 miles around mile 67 to 74. The largest is Rochfort bridge. It is about 2000 ft. long.

I have scanned pictures of these three onto my computer but don't know how to post them.

There are alot of wood trestles around.

Barry, Regina

[steve14]

There are a lot of wood trestles in CLass 1 main lines, and branches too, obviusly. As to the earlier question of when any had been built "recently", CP built one to replace one in kind on the MN&S line in Edina, I believe. This would have been about 1995 or 96. Interesting work, since we barley had anyone who still knew how to build a wood bridge. Luckily, our Construction Supervisor and the foreman had been around long enough to remember.

This was a complete job from the bottom up, all wood. Even though I had been around a while, most of my time had been on the track side prior to that, so working with a couple old head bridge people (one from the Milwaukee and one from the Soo) who had done this before was a very good education.

 CP still has a few left in the main line up near Noyes. We managed to get rid of most of the others in the US while I was there.

[J. Edgar]

....I am just truly amazed of those old extreme structures....The high ones.  Many on a curve too...{but maybe that helped their strength}.  I picture a train pulling around such a curved trestle and think about the forces pulling to the inside if it was on a slight upgrade....I understand many of these old {some original}, structures were eventually filled in with a dirt fill.  Seems the wood structures were the fastest way to get a line thru and then later they came along and made such improvements.

 also from what ive studied that was exactly it...many original Charters stipulated certain time spans roads needed to be completed in before subsidies such as Land Grants would take effect...in some cases ties went right on prairie sod with rails spiked down trais ran until money was available to make improvements...of course not all lines made money...

[Modelcar]

....I believe If one closely checks photos of old trestles....{tall ones}, it is apparent they were built in "layers".....and fastening such large timbers together, one on top of the other took some doing.  Then to make sure it stayed in place with all the forces going through it over time.....Wow...!

[J. Edgar]

from what ive found out....... piles would be as long as possible or as needed to be....the piledriver would be on top of completed piles and would simply hoist a up a new pile the desired length and drive it the ground..... thinking that old growth forrests still exsisted in the mid to late 1800's trees (piles) could easily be 100' long..if more length is needed at some point lateral braces and cross braces would support the joint between piles driven in the ground and the extended length...

[Modelcar]

....I am just truly amazed of those old extreme structures....The high ones.  Many on a curve too...{but maybe that helped their strength}.  I picture a train pulling around such a curved trestle and think about the forces pulling to the inside if it was on a slight upgrade....I understand many of these old {some original}, structures were eventually filled in with a dirt fill.  Seems the wood structures were the fastest way to get a line thru and then later they came along and made such improvements.

[CShaveRR]

Carl:

I understand the steam pile drivers, etc.....But with trestles over a hundred feet up in the air {or more}, we have to realize those weren't single timbers that were driven into the ground and reaching the full height as needed... More "rows" of timbers had to be fashioned and positioned up on top of those for the next "layer", etc.....and then fastened together...I can imagine all kinds of problems doing such necessary work and process...

Sorry, Quentin--you caught me thinking like a flatlander again.  We'll probably have to have the Mudchicken weigh in here, whenever his traveling gives him a break. 

[Anonymous]

My great grandfather was killed back in the 1880's when a train broke-through a wooden trestle in Illinois.  I'm not sure of the location or the railroad (I remember someone in the family saying it was the IC and my ancestors lived in central Illinois).  He was working for the railroad and was down in the pump-house where water from the river was pumped up to the tower for delivery to the locomotives.  The hot cinders from the steam engines had slowly degraded the structure, the investigators concluded, and the pump-house was directly underneath the trestle.

I saw the micro-filmed newspaper article about the tragedy, and how virtually everybody in the small town rushed to the scene to try and help.  They went on to list the bones that were broken in his body.  It would've been easier to list the bones that weren't broken - or enough to simply say a locomotive fell on the man.

[J. Edgar]

also as far as equipment....the Builders always found away...look at the  Stampede Pass Tunnel....it was drilled from both ends when both railheads were literaly miles away and down grade...all Eq. was packed up.......Stampede was also the first place in the US that Ingersol's new air drills were used....most Eq. came from Yakima 40 miles away and included 5 donkey engines,2 water wheels,5 large air compressors, 4 huge exhaust fans, 2 complete electric light plants 4 miles of pipe 2 machine shops 36 drilling machines 13 tons of drills 2 sawmills 60 dump cars steel rail and 2 small locomotives......all brought upto the tunnel face on wagons...they indeed were the builders of Empires back then..

[J. Edgar]

they may not be 100's of feet tall but....Pres. Loder of the Erie while building the original main made one of the early Erie's many mistakes by demanding that the entire line be built on pilings "....so that snow and other inclimate weather wont effect our trains" ...point is as early as the 1840's 4 steam powered pile drivers worked around the clock driving piles into the ground for almost 100 miles worth of track....piles which never saw a train let alone track laid on them

[wjstix]

On the western end of the Mesabi Range, the GN/BN/BNSF Mud Creek wooden trestle remained in service until about 2000 when it was replaced with a concrete structure. It saw regular service from ore trains using it, I believe one of the Plet's Express video/DVD's shows a BN train on the original trestle c.1990.

[Modelcar]

....Carl:

I understand the steam pile drivers, etc.....But with trestles over a hundred feet up in the air {or more}, we have to realize those weren't single timbers that were driven into the ground and reaching the full height as needed....More "rows" of timbers had to be fashioned and positioned up on top of those for the next "layer", etc.....and then fastened together...I can imagine all kinds of problems doing such necessary work and process....

[CShaveRR]

Quentin, I'm sure they moved the timbers on flat cars, and used pile drivers (powered by steam) to set them.  As for drilling, if they could make bits that go through rock, oak wouldn't be too much of a problem, in my estimation.

At Proviso, we have a series of thick steel girder bridges carrying seven tracks (four "mains", two hump leads, and another lead used as a runaround) over North Avenue (Illinois Route 64), six lanes of traffic.  There's almost always something on one track or another, ranging all the way up to coal trains with DP units.  And what's holding those girders up?  Wooden pilings (and plenty of 'em)!  They've been around at least as long as I have.

[Modelcar]

....Wooden trestles look like a piece of engineering design art.  I can see how it would be normally possible to build them today, but I'm not sure how they did it a hundred years ago.  Not having the machinery then as available now and where many were built {in such isolated mountainous territory}, how they moved the heavy timbers to the site and then up vertically to the structure where needed is a bit awesome to me.  And how did they drill thru such {maybe some oak}, woods to create holes for large bolts, etc....So many questions on just how it was done then....Awesome projects....!

[mudchicken]

In the southwestern US there are still plenty, including brand new replacement timber structures. (for that matter, we still have timber structures in major highway bridges in rural areas) As long as the tonnage and loading fit the bill, I imagine the railroads will continue to drive timber bridges and cap them with timber decks. 

[tree68]

I've been acrosss the Wilburton Trestle on the Dinner Train - it's quite the sight.

There have been at least two wooden trestles burn in the past few years.  One in California and the one that famously had a loaded coal train stop with a hot failed bearing right on the trestle.  Neither was a towering structure like the Wilburton Trestle , but they were both wood.

[SpaceMouse]

There used to be one near us--not Class 1 but used daily by G&W's Buffalo and Pittsburgh Railroad and was part of the B&O. It was torched last year. Here's a video. It was ruled arson the next day.

B&P Bridge Fire  

[Snoq. Pass RR]

There is a wooden trestle in Bellevue, WA along a BNSF mainline which was also used by the Spirit of Washington Dinner Train.  The trestle is the Wilburton Trestle built in 1891. The Wilburton Trestle is the longest in the Northwest at 975 long by 102 feet tall. There is a big issue over track rights going on and from what I here the line is going to be torn up and become a bike trail.  That is the biggest load of crap ever.  So I am not sure what is going to happen to the trestle, but yes this wooden trestle was used by a modern class-I railroad.

Here is a photo of the trestle being used by the Spirit of Washington.  Photo is by Komo 4 News.

Here is another photo of the trestle showing how long it is.  Photo is by the Seattle Times.

[Ted Marshall]

I just love old railroad trestles, as much as the next guy. Spanning mountain valleys or just crossing a canal, creek or river, you 've gotta admit that they're neat to look at. Even on model layouts they're usually the focal point of the entire layout because of their inherent beauty even in scale. By design, wood trestles are structurally solid, capable of supporting a tremendous amount of weight and resisting both linear and lateral movement.

The problem with wood is that, by nature, even creosote-treated timbers rot, though slowly. Even a steel trestle will corrode and eventually fail if not kept painted, but I'm sure that wood degrades much faster when exposed to the elements.

What I'm interested in knowing is how many wood trestles still exist on today's Class-I mainlines and what are the maintenance requirements on them? How old is the 'newest' wood trestle still in service today?

What I'd like to do on my next railfan trip is to get pics and vids of freight traffic moving across one or more of these engineering marvels. Any help will be appreciated.