This 2008 photo shows the Pierre Laporte Bridge (A-73) paired with the Quebec Bridge (QC 175) looking south from the Sainte-Foy shoreline. (Photo by Mightydrake from Wikipedia.)
A MODERN COMPANION TO THE OLD QUEBEC BRIDGE: With the exception of ferries, the Quebec Bridge (QC 175) provided the only way to cross the St. Lawrence Bridge downriver from the Jacques Cartier Bridge (QC 134) in Montreal, approximately 235 kilometers (146 miles) away. The bridge provided only two lanes of vehicular capacity--one lane in each direction--and soon proved incapable of handling the traffic demands of the postwar era. This was particularly evident in the winter months, when ice flows closed the river to ferry traffic.
In 1962, engineers proposed a multi-lane bridge or tunnel between Quebec City and the South Shore city of Levis to alleviate congestion on the Quebec Bridge. This proposal had surfaced at various times in the 1960s, most notably in a 1968 report recommending a suspension bridge carrying the A-640 designation along the Quebec City-Levis alignment. However, provincial officials decided in 1963 on an alignment parallel to the existing Quebec Bridge. The new span was to be less than 200 meters (650 feet) west of the old bridge.
Part of the province's nascent autoroute network, the proposed "New Quebec Bridge"--as it was called initially--was to accommodate six lanes of vehicular traffic. The project, which was projected at the time to cost C$35 million, was a joint venture of the Ministère de la Voirie du Québec (MVQ, now Transports Quebec) and Parsons Transportation Group. Dominion Bridge Company, Cleveland Bridge and Engineering Company, and Stelco (now US Steel Canada) performed most of the engineering work on the span.
Engineers selected a suspension design for the new bridge, which was to have the longest main suspension span in Canada at 667.5 meters (2,190 feet) between towers. From end to end, the bridge was slightly more than one kilometer long (3,414 feet). The two towers were 122.5 meters (402 feet) tall, about as high as a 40-story building and dwarfing the old Quebec span by 19 meters (62 feet). The arched-portal steel towers and stiffened-truss deck were characteristic of mid-20thcentury suspension bridge design, not unlike the Ammann and Whitney-designed spans in New York and Philadelphia.
Initial contracts for the anchorages and towers were assigned in the winter of 1966, with construction beginning that spring. Most of the work on the span was scheduled between April and October to avoid high winds and freezing temperatures.
This 1969 photo shows the wires that form the main cables of the Pierre Laporte Bridge being spun across the St. Lawrence River looking north toward Sainte-Foy. (Photo by Andre Voyer for Quebec Urbain.)
WEAVING A NEW SPAN ACROSS THE ST. LAWRENCE: Through much of 1966, work progressed on building the two anchorages and the caissons that were to support the two main towers. More than 172,000 cubic meters (225,000 cubic yards) of concrete were used on the entire bridge, and more than half this amount was used to build the anchorages.
The bridge's two towers were erected in 1967 and 1968; each tower weighed nearly 3,000 metric tons (3,250 tons). The towers were erected in sections at Dominion Bridge's fabrication plant near Montreal in Lachine, and were sent by barge to the construction site for final assembly. Once the towers were built, workers began to spin more than 28,000 kilometers (17,000 miles) of wire across the St. Lawrence River to form the bridge's two main cables. The two cables each measured 61 centimeters (24 inches).
Next came the raising of the suspended deck sections. Through the summer and fall of 1969, more than 4,500 metric tons (5,000 tons) of structural steel were shipped by truck to five sites near the construction site, where the steel was assembled into 38 separate sections, each measuring 24.4 meters long by 28 meters wide (80 feet long by 92 feet wide). These sections were lifted into place in the spring and summer of 1970.
The "New Quebec Bridge" had been rechristened the "Frontenac Bridge," after the late 17th century governor of the New France colony, during the construction period. However, less than one month before it was to open, the bridge was renamed once again in honor of Pierre Laporte, who had served as the province's vice premier and labor minister before he was kidnapped and murdered by the terrorist group Front de Liberation du Quebec (FLQ).
The Pierre Laporte Bridge was opened to traffic on November 2, 1970, connecting an already completed section of Henry IV Autoroute (A-73) to the north with the newly extended A-20 to the south. The C$55 million cost of the bridge exceeded the C$35 million cost projected seven years earlier. The bridge still has the longest main suspension span in Canada and remains the longest non-tolled suspension bridge (based on the length of the main span) in the world, but now is ranked 45th longest overall worldwide (versus 14th longest when it opened).
Designed for a capacity of 90,000 vehicles per day (AADT), the Pierre Laporte Bridge now handles approximately 115,000 vehicles per day. In the early 1990s, the Ministère des Transports du Québec (MTQ) studied the possible conversion of the six-lane, fixed barrier roadway to a seven-lane roadway with a moveable barrier; however, no action was made after the study, and there are no current plans to expand vehicular capacity between Quebec City and the South Shore at the present time. In the early 2000s, Montreal-based engineering firm Genivar oversaw a C$30 million project to renovate the span, including the replacement of concrete slabs, rehabilitation of the anchorages, and rebuilding of approach supports.
This 2007 photo shows the southbound Autoroute Henri IV (A-73) approaching the Pierre Laporte Bridge. (Photo by Bill Branch, www.branchdesign.com.)
Type of bridge Construction started Opened to traffic Length of main span Length of each side span Length, anchorage to anchorage Width of bridge Width of roadway Number of traffic lanes Height of towers above mean high water Clearance at center above mean high water Concrete used in anchorages Total concrete used on bridge Reinforcing steel used towers Reinforcing steel used in suspended span Reinforcing steel used in entire structure Number of cables Diameter of each of two cables Total number of wires per cable Total length of wires Foundation type Cost of original structure
SOURCES: "Engineers Urge Span to Levis," The Montreal Gazette (10/11/1962); "Second Bridge Will Be Built at Quebec City," The Montreal Gazette (7/12/1963); "Spring Dateline Set for Work on Quebec Bridge," The Quebec Chronicle-Telegraph (3/15/1966); "Bridge Gets $6.2 Million Tower Order," The Montreal Gazette (4/24/1967); "Steel Cables for Bridge Being Run Across River," The Quebec Chronicle-Telegraph (8/17/1968); Plan de Circulation et de Transport: Region Metropolitaine de Quebec, Ministère de la Voirie du Québec (1968); "Where Would We Be Without the Truck?," En Ville (8/31/1970); "New Bridge Renamed in Honor of Assassinated Labor Minister," The Quebec Chronicle-Telegraph (10/22/1970); "Laporte Bridge Opens," The Montreal Gazette (11/03/1970); "One of the Big Events of 1970: The Opening of the Pierre Laporte Bridge" by Eddie Labrie, L'Artisan (12/23/1970); Cleveland Bridge UK Ltd.; Genivar, Inc.; Ministère des Transports du Québec; Quebec Urbain; U.S. Steel Canada; Félix-Mathieu Bégin; Nicolas Janberg; Rush Wickes.
A-73 shield by Wikipedia. Lightpost photos by Douglas Kerr.