View source for Peterborough Lift Lock

{{Short description|Boat lift}}
{{Use Canadian English|date=January 2023}}
{{More citations needed|date=April 2022}}
{{Infobox waterlock
|lock_name   = Peterborough Lift Lock
|image= PeterboroughLiftLock23.jpg
|caption= Front view of the Peterborough Lift Lock
|waterway = [[Trent-Severn Waterway]]
|country = [[Canada]]
|province = Southern [[Ontario]]
|maint   = [[Parks Canada]]
|operation = Hydraulic
|first    = {{Start date|1904}}
|latest   = 1980s
|length = {{convert|43|m}}
|width = {{convert|10|m}}
|fall = {{convert|19.8|m|ftin}}
|sealevel = 
|enda =
|distenda =
|endb =
|distendb = 
| map_cue= 
| map_image= 
| map_text= 
| map_width= 
| coordinates= {{coord|44|18|27|N|78|18|03|W|region:CA-ON_type:landmark|display=inline,title}}
| extra= {{designation list|embed=yes|designation1=Canada|designation1_date=1979}}
}}
[[File:Peterborough Lift Lock.jpg|thumb|Peterborough Lift Lock HDR]]
[[File:Peterborough Lift Lock.JPG|thumbnail|200px|right|Peterborough Lift Lock (side view)]]
[[File:Peterborough Lift Lock museum.JPG|thumbnail|200px|right|Exhibition of historical lift models at the Peterborough Lift Lock]]

The '''Peterborough Lift Lock''' is a [[boat lift]] located on the [[Trent Canal]] in the city of [[Peterborough, Ontario]], [[Canada]], and is '''Lock 21''' on the [[Trent-Severn Waterway]].

For many years, the lock's dual lifts were the highest [[hydraulic]] boat lifts in the world, raising boats {{cvt|65|ft|m}}. This was a considerable accomplishment in the first years of the 20th century, when conventional locks usually only had a {{cvt|7|ft|m}} rise.

In the 1980s, a visitor centre was built beside the lock. It offers interactive simulations of going over the lift lock in a boat, and historical exhibits detailing the construction of the lift lock.

Residents and visitors [[ice skating|skate]] on the canal below the lift lock in the winter.

The Peterborough Lift Lock was designated a [[National Historic Sites of Canada|National Historic Site]] in 1979,<ref>{{cite web |title=Peterborough Lift Lock National Historic Site of Canada |url=https://www.pc.gc.ca/apps/dfhd/page_nhs_eng.aspx?id=486 |website=Directory of Federal Heritage Designations |publisher=Government of Canada |access-date=29 July 2018}}</ref><ref>{{CRHP|11449|Peterborough Lift Lock}}</ref> and was named an [[List of historic mechanical engineering landmarks|Historic Mechanical Engineering Landmark]] by the [[American Society of Mechanical Engineers]] in 1987.<ref name="ASME">{{cite web |url=http://www.asme.org/Communities/History/Landmarks/Peterborough_Hydraulic_Canal.cfm|title=Peterborough Hydraulic (Canal) Lift Lock (1904)|access-date=2009-01-19|work=Landmarks|publisher=American Society of Mechanical Engineers}}</ref>

The Trent-Severn has a similar hydraulic lift lock, the [[Kirkfield Lift Lock]], at its summit near [[Kirkfield, Ontario|Kirkfield]], with basins of the same dimensions, but which has a smaller vertical lift.

==Description and operation==
The lock has two identical bathtub-like ship [[Caisson (engineering)#Boat lift caissons|caissons]] in which vessels ascend and descend. Both caissons are enclosed at each end by pivoting gates, and there are pivoting gates at the upper and lower [[Canal reach|reaches]] of the canal at the junctions with the caissons. The gates on the caissons fit into slots on the gates on the reaches, so that they open in unison.

Each caisson sits on a {{cvt|7.5|ft|m}} diameter [[Hydraulic cylinder|ram]], the shafts for which are sunk into the ground, are filled with water, and are connected with a pipe that has a crossover control valve. The caissons are guided up and down on either side by rails affixed to concrete towers.<ref>{{cite web |title=Peterborough Hydraulic (Canal) Lift Lock |url=https://www.asme.org/about-asme/who-we-are/engineering-history/landmarks/205-peterborough-hydraulic-canal-lift-lock |publisher=The American Society of Mechanical Engineers |access-date=29 July 2018}}</ref>

The caissons are {{cvt|140|ft|m}} long, {{cvt|33|ft|m}} wide, and {{cvt|7|ft|m}} deep and when filled with {{convert|228093|impgal|m3 L}} of water weigh {{convert|1700|ST|tonne}}.<ref name="IC_Ops">{{cite web|title= Peterborough Lift Lock |url= http://collections.ic.gc.ca/waterway/rg_eng_i/pe_e.htm|archive-url= https://web.archive.org/web/20050402101134/http://collections.ic.gc.ca/waterway/rg_eng_i/pe_e.htm |publisher= [[Industry Canada]]|archive-date= 2005-04-02|access-date= 2009-09-21}}</ref>

No external power is needed: the lift lock functions by [[gravity]] alone using the [[counterweight]] principle. One caisson always ascends and the other always descends during each locking cycle. When one caisson reaches the top position, it stops {{convert|12|in|cm}} below the water level of the upper reach, and the control valve is closed;<ref name="IC_Ops" /> [[Siemens]] ultrasonic sensors are used to help determine the differential.<ref>{{cite web|title= Improved level measurement for historic lift lock|url= http://www.engineeringtalk.com/news/sie/sie214.html |work= engineeringtalk|publisher= Pro-Talk|date= 2004-09-03|access-date= 2009-09-21}}</ref> The upper reach and top caisson gates open, and water flows into the top caisson until the level equalizes. The weight of the extra foot of water is {{convert|144|ST|tonne}}, making the total weight of the upper caisson {{convert|1844|ST|tonne}}.<ref name="IC_Ops" /> Any vessels that just ascended in the top caisson exit into the upper reach, and any new vessels making a transit of the lock then enter the bottom or top caisson from the lower or upper reach respectively. Once the vessels are secured, all gates are closed and the crossover valve in the connecting pipe between the ram shafts is opened. Since the upper caisson weighs more than the lower caisson (1,844 vs 1,700 tons), it pushes down on its ram, forcing out water from its shaft via the connecting pipe into the shaft of the bottom caisson. The force pushes up on the bottom caisson's ram, raising the caisson up to the top position. When the gate of the newly descended top caisson and lower reach gates open at the bottom, the extra foot of water flows out and equalizes with the water level in the lower reach of the canal, and any descended vessels exit, allowing the cycle to start over again.<ref name="IC_Ops" />

== History ==

The lift lock was designed by [[Richard Birdsall Rogers]], a superintendent of the [[Trent Canal]] (part of the [[Trent-Severn Waterway]]). In 1896, he travelled to [[France]], [[Belgium]] and [[England]] to see existing examples in operation.

Part of the reason that the lift lock was built was political.  At the time a [[1896 Canadian federal election|federal election]] was taking place and in order to shore up local support the project was fast tracked.  In 1896 construction was approved and contractors signed on prior to any real working drawings being ready.  The government still fell, and Richard Rogers, who was concerned about his links to the former administration, only released portions of the working drawings bit by bit.  It worked, allowing him to remain on the job as the main designer.

The final project included many engineering firsts. It was the first lock to be built out of concrete, and at the time was the largest structure ever built in the world with unreinforced concrete.<ref name=angus>Angus, James T. ''A Respectable Ditch: A History of the Trent-Severn Waterway 1833-1920''. McGill-Queens University Press, Montreal and Kingston, 1988.</ref>

Construction was by Corry and Laverdure of Peterborough, which excavated the site and built the concrete towers and lock, and [[Dominion Bridge Company]] of Montreal, which completed the metal work including rams, presses and large caissons, and was finished in 1904. The lift lock officially opened to the public to a crowd of thousands on 9 July 1904, and remains in full use today.

== See also ==
*[[List of boat lifts]]
*[[Canal lock]]

== References ==
{{reflist}}
{{refbegin}}
*{{cite web|last= Turner|first= Larry|title= Peterborough Lift Lock|url= http://collections.ic.gc.ca/heirloom_series/volume5/208-209.htm|archive-url= https://web.archive.org/web/20060210010620/http://collections.ic.gc.ca/heirloom_series/volume5/208-209.htm |publisher= Industry Canada|archive-date= 2006-02-10|access-date= 2009-09-21}}
{{refend}}

== External links ==
{{commons category|Peterborough lift locks}}
*[https://web.archive.org/web/20060318151229/http://www.ftsw.com/liftlock/  Site for the lift lock's 100th anniversary]
*[http://www.hanifworld.com/liftlock.htm Peterborough Lift Lock views]
*[http://www.pc.gc.ca/lhn-nhs/on/trentsevern/visit/visit6/lock21.aspx Lock 21 - Peterborough Lift Lock] - Trent-Severn Waterway National Historic Site of Canada

{{NHSC}}
{{Peterborough, Ontario}}
{{Authority control}}

[[Category:Boat lifts]]
[[Category:Canals in Ontario]]
[[Category:Locks of Canada]]
[[Category:National Historic Sites in Ontario]]
[[Category:Buildings and structures in Peterborough, Ontario|Lift Lock, Peterborough]]
[[Category:Transport museums in Ontario]]
[[Category:Canal museums]]
[[Category:Museums in Peterborough, Ontario]]
[[Category:Transport in Peterborough, Ontario]]
[[Category:Transport infrastructure completed in 1904]]
[[Category:Transport buildings and structures in Ontario]]
[[Category:1904 establishments in Ontario]]