Two of several bridges carrying railroad tracks over the Desjardins Canal.

Railroad bridges are intriguing because they carry an extreme load. The engineering that goes into supporting freight trains far exceeds that of engineering to support other means of transportation (except bridges that carry boats — those actually exist!). Let’s look at two of the railroad bridges over the Desjardins Canal — the oldest and the youngest (see Figure 1).

Figure 1: The Desjardins Canal used to provide passage to cargo ships carrying goods to and from the Dundas industrial area until the railroads were built. Four of the seven bridges there today are railroad bridges.

The first railroad bridge over the canal is the eastern-most bridge (harbour side), built in 1853 by the Great Western Railroad Company, carrying two tracks accessing the large rail yard to the east. The latest railroad bridge, built right next to it in 2016, added a third track to improve GO Transit service to Hamilton (see Figure 2).

Figure 2: Two railroad bridges, one with foundations dating way back to 1853 and the other just commissioned in 2016, have a fascinating contrast in design spanning 163 years (left)! The old bridge with the new deck in the foreground hides the newest bridge right behind it (right), as well as several more bridges over the canal, including the floating pedestrian bridge (topics for future articles).

The original bridge on these abutments was a wooden swing bridge allowing tall ships to pass through the canal. It collapsed in 1857 under the derailment of a steam locomotive, leaving fifty-nine people dead — a terrible accident known as the Desjardins Canal Disaster (see Figure 3).

Figure 3: Rendering of the accident after the train fell through the wooden swing bridge into the canal. Image courtesy of Local History and Archives, Hamilton Public Library.

The bridge was replaced right away with a steel plate girder swing bridge on the same original stone abutments. But in 1897, the bridge was replaced AGAIN with a stronger fixed-span steel plate girder bridge, bringing an end to the passage of tall ships (see Figure 4).

Figure 4: This 1870s photo on the left shows the steel swing bridge in the background, built right after the Desjardins Canal Disaster. In the foreground is a local toll bridge, later torn down, leaving only the pier foundations still visible today. The photo on the right looking west through the canal is of the third bridge in the foreground on the old stone abutments. Photos courtesy of Local History and Archives, Hamilton Public Library.

The original stone abutments remain in use today supporting the latest (fourth) superstructure built in the 1980s with prestressed concrete box girders. In 2016, a neighbouring bridge was built to carry a third track to the Hamilton CN Rail Freight Depot and the new GO station (see Figure 5).

Figure 5: The old bridge is a single-span structure with large masonry abutments. The new bridge is a three-span structure with much smaller (more efficient) concrete piers.

The main span of the new bridge over the canal is a robust deep-plate girder system made of weathering steel (much more resistant to corrosion), and the back spans connecting the piers to the abutments at the top of the slopes are made of two wide precast deck structures filled with ballast, very common in railroad bridge construction today. The new concrete bridge piers were also made to mimic the stone of the older neighbouring bridge (see Figure 6).

Figure 6: A special form liner was used on the new concrete piers to make them look like the older neighbouring stone abutments (left). Note the “2016” birthday stamp on the new abutment wall at the top of the slope (right).

One of the downsides of weathering steel is that it tends to bleed over time onto the concrete piers, leaving long, rust-coloured streaks produced during rainfalls (more so than regular steel). For this reason, the ends of the girders are often painted to reduce or eliminate staining (see Figure 7).

Figure 7: Weathering steel tends to bleed rust onto its concrete supports, so the ends of the girders are often painted (left). A neighbouring railroad bridge over the same canal made of regular steel seen here (not painted) causing rust streaks on the pier (right).

The deeper the girder is, the higher its capacity to carry loads. Its web (the tall vertical plate between the flanges), however, also becomes more flimsy, subject to buckling without additional supports and stiffeners. This is why there are gusset plates (stiffeners) at the bottom of the web along with a series of cross braces between the girders (see Figure 8).

Figure 8: Small gusset plates bolted to the bottom of the girder’s web prevent the crushing of the web where it acts in compression while the bottom flange is in extreme tension under train loading (left). Cross bracing is added to stabilize the bottom of the girders (right).

The two old bridge abutments built in 1853 have supported several different superstructures over the years. Today, the span is made of precast box girders laterally bolted together with four steel rods, making them act as one monolithic structure instead of independent girders (see Figure 9).

Figure 9: Precast box girders supporting the ballasted tracks. The four grout pockets (see the arrows pointing to two of these) on the sides of the box girders are evidence of the hidden steel anchor rods used to bolt the girders together.

There are also steel brackets near the top of the abutments facing the canal, which were probably used for a temporary jacking frame to replace the deck in the 1980s, left in place in the event that the deck needs to be replaced once again (see Figure 10).

Figure 10: Two steel brackets bolted at the top of the old stone abutments allowed for a temporary jacking frame to replace the deck (left). From the old abutments to the box girders to the new plate girders, three different technologies work together carrying trains to and from Hamilton (right).

It’s always fascinating to see old infrastructure next to new, telling the story of the country’s need for transportation decades ago and how our ancestors delivered on that need. And it becomes a testament to our growth and industriousness as new infrastructure is built to increase capacity over time. When walking by these structures, look at them closely and don’t forget to be impressed. Be safe!

Have you seen an interesting building or piece of infrastructure in or around Burlington that you’d like Eric Chiasson, your personal engineer, to write about?

Send us your suggestions, comments, or questions to articles@local-news.ca and we’ll see what Eric can find out!

Sources:

Structure Magazine. Desjardins Bridge Disaster. Url: https://www.structuremag.org/?p=15353 (accessed Dec. 19, 2021).

Hamilton Public Library. Local History and Archives. Desjardins Canal Disaster. Url: https://lha.hpl.ca/articles/desjardins-canal-disaster (accessed Dec. 19, 2021).

Historic Bridges.org. Desjardins Canal Railway Bridge. Url: https://historicbridges.org/bridges/browser/?bridgebrowser=ontario/desjardinscanalrail/ (accessed Dec. 19, 2021).

The Spectator. March 12, 1957. 59 Die in Desjardins Canal Bridge Railway Disaster. Url: https://www.thespec.com/news/hamilton-region/2016/09/23/march-12-1857-59-die-in-desjardins-canal-bridge-railway-disaster.html (accessed Dec. 19, 2021).

For more info on the Desjardins Canal, read my articles How It Works: The Desjardins Canal, and How It Works: The Desjardins Canal High Level Bridge.

For more information on the author: https://www.linkedin.com/in/eric-chiasson-10601082