PLACENTIA, N.L —Construction continues on the new $40.6 million lift bridge replacement in Placentia, N.L., while the old structure reopened recently after being closed temporarily for repairs and maintenance.
The Sir Ambrose Shea Lift Bridge reopened on Oct. 12, after the department of transportation and works advised the public that the structure would be closed to vehicles for repairs and maintenance.
The closure marks the start of the Placentia lift bridge repair project, which will take about six weeks to complete and make the bridge fully operational.
The bridge, which has been plagued by problems since it became stuck at an angled position in August, consists of two approach spans and one centre vertical lift span each 100 feet in length. The total weight of the centre span is 100 tons. It can be raised in about one-and-a-half minutes. Clearance under the span in the down position is 10 feet, and when raised is 70 feet.
Construction on the new lift bridge is being built directly adjacent to the existing bridge, which will remain open to traffic until the new bridge is finished.
"Planning the replacement bridge has led to a variety of problems," said Vince Kerrivan in a research paper.
"Initial estimates to complete the project were double of what was originally planned. The designs had to be revised to reduce costs. Also, to keep the bridge viable, short term repairs were necessary for the 51-year-old bridge which considerably slowed down traffic in the community."
Kerrivan, who is an undergraduate student at the Faculty of Engineering and Applied Science at Memorial University in St. John’s, said weight restrictions were placed on the bridge, which banned heavy commercial vehicles from using it.
H.J. O’Connell, a division of Bird, is the lead in a joint venture with Vancouver Pile Driving Ltd. in the construction of the new vertical lift bridge in Placentia.
During construction, the team has encountered tidal ranges of over three metres with swift currents. The piling required for the south pier and south abutment has increased substantially due to changes in geotechnical conditions, which has required deeper driven piles.
Once the bridge substructure is complete, structural steel will be erected. The centre span will be the major challenge as it involves shutting down the shipping lane to allow the erection of a 100 ton span using the mechanical and electrical systems of the permanent structure. The entire span of the bridge will be 100 metres, consisting of two approach spans and a centre 30 metre span.
The new bridge project includes the realignment of a portion of Route 100 leading to and from the new bridge as well as the removal of the existing bridge. The project is scheduled to be completed in 2016.
The Sir Ambrose Shea Lift Bridge was constructed in 1961 and is at the end of its lifecycle. The construction of a lift bridge was necessary to allow fishing boats to enter and leave Placentia, while allowing vehicles to drive between Jerseyside and Placentia.
The difficult environmental conditions of wind, waves and tide created a challenging design for the bridge. Work on the bridge started in August 1959 and by December 1960 the abutments, piers, and approach spans had been completed.
However, winter and the abnormal ice conditions in spring 1961, delayed resumption of work until May 1961, when the first shipment of steel for the centre span arrived at the site.
"When the American base was set up in nearby Argentia, during the Second World War, a pontoon bridge was built to cross the gut," said Christopher Clark in a research paper.
"Unfortunately, the bridge didn’t last long with the rough tides and sea ice in the area."
Clark, who is also an undergraduate student at the Faculty of Engineering and Applied Science at Memorial University, said a ferry capable of carrying several vehicles and passengers was used to cross the gut in the 1950s.
Finally, plans were made to construct a bridge that was capable of lifting to accommodate vessel traffic.
The town of Placentia is located on the western end of the Avalon Peninsula on the east side of Placentia Bay. Placentia consists of the amalgamated towns of Placentia, Jerseyside, Freshwater & Dunville and is the centre hub for the fishing industry.
Harbours in the area are located inside the northeast and southeast arms which are connected to the sea by a small passageway commonly referred to as the gut. The gut separates the towns of Jerseyside and Placentia.
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