The magnificent and mighty trestle bridges of the 19th Century

The first use of timber for building bridges probably emerged when someone decided to place a log over a stream to cross over. However, the 1830s boom in the development of the railroad started a new era in the building of rail bridges and pushed the engineers to create towering wooden bridges that have become synonymous with that era.

These towering timber trestles are considered the only railroad related technology that wasn’t developed in Europe.

 

A 203 foot high wall of wood – The Cedar River Logging Trestle in Washington State

 

A home-made log bridge. The men sitting atop it give an idea of its height, and the diameter of the redwood logs used for construction Company photo – date unknown

 

Early timber bridges had their drawbacks. Untreated lumber only lasted about 20 years and locomotives could easily cause the wood to catch fire.

 

Trestle, Central Pacific Railroad, c.1869.

 

Deer Island Logging trestle

 

Initially they were a quick way to get the route open but once established, the owners usually had them replaced with steel bridges or filled.

 

A home-made log bridge. The men sitting atop it give an idea of its height, and the diameter of the redwood logs used for construction Company photo – date unknown

 

Trestle accross McBride Creek just north of Columbia City

 

Trestle accross McBride Creek just north of Columbia City

 

Bridge on Orange & Alexandria [Virginia] Railroad, as repaired by army engineers under Colonel Herman HauptInstead, the Pacific Northwest of the United States and British Columbia in Canada took the lead in this field, primarily due to the widespread availability of lumber that was readily available from forests near the construction sites.

These timber trestles were generally built in two designs with distinct features and functionality.

The most common of the pair was known as the Pile Trestle, which consisted of bents spaced 12 to 16 feet apart.

Each of these bents consisted of some three to five timber poles which were pounded straight down the ground using a pile driver. To create better stability, the outer posts were usually battered creating an angle outwards.

The top of the posts which were uneven were usually cut to level with the cap during the construction, which in turn provided the support for the stringers and planks that held the weight of the rail.

For the taller timber trestle, the bent framed was used, the frame bents usually used the timber that was square, unlike pile bents, and sub sills or mud sills often acted as the foundation of the structure.

Montana’s massive 214 foot high Two Medicine Creek timber trestle on the Great Northern Railway

 

A 203 foot high wall of wood – The Cedar River Logging Trestle in Washington State

 

The Dale Creek Bridge, 2 miles west of Sherman, Wyoming.

 

Trestle construction

 

Erie – Constructing Trestle over B&S Railroad

 

Erie trestle construction

 

In all cases, the curvature of the rail line was minimised through long graceful curves across several trestles, and by turning the rail line gradually throughout the length of the longer trestles. The largest of the wood frame trestles, the trestle at Mile 87.9 crossing the West Canyon Creek, was a stupendous structure, 750′ long and 182′ high, and turned the rail line almost 90 degrees over its entire length at the head of the canyon In all cases, the curvature of the rail line was minimised through long graceful curves across several trestles, and by turning the rail line gradually throughout the length of the longer trestles. The largest of the wood frame trestles, the trestle at Mile 87.9 crossing the West Canyon Creek, was a stupendous structure, 750′ long and 182′ high, and turned the rail line almost 90 degrees over its entire length at the head of the canyon

These frame bents were built in the form of stories that were usually between ten to fifteen feet high. In the case of the extremely tall trestles, the individual sections of the bent were built flat on the ground as a single or double storey and were then lifted up on a high line where it was then lowered and fitted on the rising structure, the process was then repeated for the next level.

At the peak of the timber bridge construction a total of a dozen tall timber bridges was built, none of which exist anymore. Most of these highest bridges were built to enable transportation of log and were constructed in the Washington state in the US and on Vancouver Island in British Columbia, Canada.

The sad aspect of these bridges was that the logging companies often considered these bridges as a mean of sucking out the timber from a thickly forested region, once the lumber was all transported out the bridges were abandoned without any remorse.

These timber bridges were built from lumber as it was readily available and highly inexpensive as compared to steel, however, the bridges came with a number of drawbacks.

Here is another story about bridges from us:The Ponte Vecchio: The only bridge in Florence that survived WW2, because Hitler liked it

The continuous transportation made these bridges weaker over time and prone to fire – they were made from wood, after all. The bridges over time became weak and often the workers were seen hopping off the train once approaching the weak wooden bridges only to run back and then ride it after the bridge was crossed.