Peterborough Lift Lock - Trent-Severn Waterway, Ontario

Our overall transportation system is full of engineering marvels. This is especially true for our historic canals. The Peterborough Lift Lock is also known as Lock 21 of the 240-mile-long (386 kilometers) Trent-Severn Waterway, near Peterborough Ontario, Canada, which connects the Georgian Bay at Port Severn. the Kawartha Lakes region and Lake Ontario at Trenton. It is located along the Otonabee River and is the Peterborough Lift Lock National Historic Site. At 65 feet in height or 19.8 meters, it was the highest hydraulic lift lock in the world when it opened in 1904. In fact, the second-highest hydraulic lift lock is also located along the Trent-Severn Waterway, at Lock 36 in Kirkfield, Ontario. Construction on the Peterborough Lift Lock took place from 1896 through 1904, using mostly local labor to build the unique lock. The Peterborough Lift Lock was declared a national historic site in 1979.

During the late 19th Century, Superintending Engineer Richard Birdsall Rogers (R.B. Rogers) was looking at the 65-foot lift required for the Trent-Severn Waterway in Peterborough. One solution would have been to construct a series of flight locks, such as what was built along the modern Erie Canal in Waterford, New York. Rogers investigated canal locks in Europe and found that a hydraulic lift lock would be the answer. A traditional flight lock system would have taken around three hours to transit this height. However, a hydraulic lift takes 90 seconds to traverse from start to finish. Although in practice it takes more than 90 seconds, due to the 144 tons of water that is transferred as the chambers of the lock go up and down. Powered by gravity, this enables the lifts to operate in two counter-balanced, bathtub-like chambers that would have otherwise required several locks if a flight of locks was chosen instead.

Each chamber of the lock has a piston, and they are connected, so they operate as a counterbalance to each other. Think of it as a giant teeter-totter. The lockkeeper only needs to add a small amount of water to the upper water box and it will begin to descend, and push the other box upwards. When water is let into the upper chamber, a connecting valve is opened and the heavier chamber automatically descends, forcing up the lower chamber to start a new cycle. Going between the two chambers of water, and beneath the giant rams that hold each basin up, is a 12-inch (30-centimeter) crossover pipe with a valve that gets open and shut so water can transfer from one side to another. Designed to not use any electricity, the tower in the middle with the red roof and flag on top that now serves largely as decoration was the original lockmaster’s position when the crossover valve operated with a pulley system. 

The lock structures that raise and lower the chambers use a riveted pony truss design to bear the load of the water they contain, and the truss-like lift locks were built by Dominion Bridge Company. Concrete, and more specifically compressed Portland cement, also make up a fair amount of the Peterborough Lift Lock. The lift lock is noteworthy for the substantial use of concrete in its construction, over 20,000 cubic meters of concrete. When it was built, the lift lock was the largest unreinforced concrete structure in the world. It is also reported to be the largest and tallest structure to use a compressed form of Portland cement.

Additionally, the Peterborough Lift Lock was originally designed not to use electricity, but electricity was added to the operation of the lock during the 1970s after one of the gates gave way, as water and a boat flowed off the side. Only minor injuries were suffered, but the decision to upgrade the gates was made due to that event. The only electricity the entire operation of the lift lock uses today is to control the automatic gates, navigation lights, and signage. The lift lock itself still operates using water, gravity, and the crossover valve that throttles the water flow. 

The Peterborough Lift Lock has its own set of lore as well. For as beautiful of a structure as it is, the lift lock may also be haunted. It is said that one construction worker from when the lock was being built has spent his afterlife wandering the site of his last job. According to local legend, one worker was entombed in the lift lock as cement was poured into the middle of the structure's three pillars. It is also said that the gravesite of R.B. Rogers, the superintendent who designed the lift lock, is angled in such a way that differs from the rest in the local cemetery so that his tombstone faces his legacy. My own visit was not haunted, but I certainly learned a lot when I visited the Peterborough Lift Lock. It's also impressive to see the lift lock in person. There is a visitor's center near the lift lock, but it was closed during my visit. I enjoyed discovering the history and exploring what the lift lock has to offer, including a few nooks and crannies I didn't anticipate coming across.

Historical marker explaining how the Peterborough Lift Lock operates.

There is a tunnel under the lift lock for traffic to cross on Hunter Street East, along with a staircase that will take you to the top of the lock.

View of the Trent-Severn Waterway from the top of the Peterborough Lift Lock.

Upper chamber of the lift lock.

Looking towards the upper chamber of the lift lock. This would be for the right chamber.

The tunnel through the lift lock has an observation window where you can see the lower chamber of the lift lock and the canal below. The Trent-Severn Waterway is mostly a recreational canal at the time, as commercial traffic uses the larger Welland Canal between Lake Erie and Lake Ontario. There weren't any boats that were using the locks when I visited, but it was still neat to see. 

Underneath the hydraulic lift lock.

Historical plaque honoring the superintendent of the lift lock construction, R.B. Rogers. He was through and through a Peterborough man. At the time the lift lock was built, the Trent-Severn Waterway was known as the Trent Canal.

Hunter Street East tunnel through the lift lock.

View of the upper chamber from the lower part of the lift lock.

It is impressive to see the lift lock from ground level.

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Sources and Links:
Hiking the GTA - Peterborough Lift Lock
The Travels of Tug 44 - Peterborough Lift Lock - Ontario
Peterborough & The Kawarthas - Peterborough Lift Lock

Parks Canada Directory of Federal Heritage Designations - Peterborough Lift Lock National Historic Site of Canada
Parks Canada - Lock 21 - Peterborough Lift Lock /  Trent-Severn Waterway National Historic Site
HistoricBridges.org - Peterborough Lift Lock
BoatBlurb - Behind-the-Scenes of the Peterborough Lift Lock
Union of Canadian Transportation Employees - Construction of the Peterborough Lift Lock - History and Quick Facts
Commuter Cruiser - Fun Facts About the Highest Lift Lock in the World! Peterborough Lift Lock
American Society of Mechanical Engineers - #205 Peterborough Hydraulic (Canal) Lift Lock
Trent-Severn Waterway - The Trent Severn Waterway Lock # 21
Journal of Commerce - Ghost of construction worker said to work overtime at Trent Severn Canal lock in Peterborough, Ontario