Confederation Bridge

Linking Prince Edward Island to the rest of Canada was a project that generations of engineers had been working on since the start of the 20th century and which became reality in 1997 through the use of construction methods that could prevail over an extreme climatic environment. VINCI Construction Grands Projets was approached by Strait Crossing Development Inc. to develop, build and operate a dual-lane, 12.9-km bridge. This cantilever bridge consists of 44 piers with a 250-m span and two access viaducts in prestressed reinforced concrete.

background

The longest over-water bridge ever built was opened to traffic on May 31, 1997. This new infrastructure joined two Canadian provinces: Prince Edward Island and New Brunswick, thereby turning Prince Edward Island into a «peninsula». This massive structure was the culmination of nearly a century of dreams and hard work. The idea of a fixed road link to continental Canada dates back to the beginning of the 20th century. Already in 1901, the federal government had decided to grant this Canadian island province an annual subsidy to find the means to overcome its isolation and ensure a means of unbroken contact with the rest of the country. In 1986, Public Works and Government Services Canada was given the responsibility of looking into a bridge connecting the island to the mainland, which resulted in the official announcement of the construction of a bridge on December 2, 1992. This announcement led to a lively debate, and a referendum was held on joining the island permanently to the rest of the country. There was a 59% «yes» vote, and construction started.

technical overview

With a length of 12.9 km including two access viaducts, the bridge spans 11 km of the Northumberland Strait. The bridge has 61 piers (45 for the bridge alone and 16 for the accesses), which have a record span of (for a prestressed concrete structure) 250 m to limit the number of piers in deep water and not hamper the ice from breaking up. A massive concrete shield protects the piers. This segmented shield was specially designed to raise ice sheets and break them by bending. The bridge was designed to use major precast and prestressed components weighing up to 7,500 tonnes, made of grade B55 and even B100 grade high-performance concrete where the ice shields are concerned.
Given the type of ground and the depth of the water, the foundations of the main structure were superficial foundations. They were built using precast reinforced concrete elements, laid in a ring footing prepared in advance and filled with concrete pumped underwater. Pier bases were fitted on the segmented summit of the foundation plates with a sufficient gap in-between. The bridge deck components were also prefabricated in 195-m sections.
The first pier base was installed using a one-of-a-kind floating crane, the Svanen, in October 1993. At the peak of construction, this unique crane with a lifting capacity of 7,000 tonnes allowed for the weekly assembly of 175 components of the main bridge, including 44 beams with a span of 250 m, which was a technical and logistical feat. Then, ice shields were installed to break up and melt the ice in the strait by forcing it over their cone structures.
The navigation channel of the bridge span has a clearance of 172 m and is 49 m above sea level, allowing for the passage of large cruise ships.

The bridge was designed to last 100 years. Its design is quite resistant to the extreme weather conditions of the Northumberland Strait.

IMPACT

This structure focused on two major challenges: safety and the environment.
First, driver safety was a priority. This is why the bridge was designed with a large roadway (11-m wide, including two 3.75-m lanes and two 1.75-m hard shoulders for breakdowns). In addition, 1.1-m-high ultra-resistant reinforced concrete safety walls were erected to prevent cars from skidding off the bridge. The roadway was also designed with curves to help drivers stay awake and prevent drowsiness, which a rectilinear roadway may produce.
In addition, the design of the structure paid special attention to the environment. Design and construction methods were developed by taking into consideration the specific land and sea environment of the construction site. Nest boxes were built for ospreys and other endangered species in the Cape Jourimain Nature Centre. Also, three key areas were identified to develop a new seabed for lobsters and other plants and crustaceans.
The Canadian Construction Association gave us the “Environmental Achievement Award” for surpassing governmental requirements in project management.

Project participants

Client
Strait Crossing Development Inc.

Project management
Buckland & Taylor

Key figures

Implementation dates
October 1993 to May 1997

Concrete
420,000 m3

Cement
160,000 t

Reinforcements
55,000 t