The comments contained below reflect solely the personal and professional opinions of the authors of this text and should in no way be interpreted as a position taken by their respective employers.
A security issue
The question of a new road link between Lévis and Quebec does not only arise in terms of traffic level: public safety issues and the need to support economic activity not only in the greater Quebec region, but also Saguenay–Lac-Saint-Jean and the North Shore, often overlooked during discussions on the subject, are in our opinion the most important. Indeed, with eastern Quebec having only one high-capacity highway link, a partial or total closure of the Pierre-Laporte bridge would very likely endanger public safety and economic activity in Quebec. The Pierre-Laporte bridge as well as the structures located on the north and south banks have already passed the 50-year mark (1970) and will have to undergo major renovation and rehabilitation work which will certainly lead to lane closures. We cannot exclude a major accident or a natural disaster either.
Indeed, the Quebec region is in an active seismic zone with a high probability of major earthquakes. The Canadian code governing the design of bridges designates so-called “essential” structures.1» when these are essential to the integrity of regional transport as well as to the economy or security of the region. These structures are designed to remain fully operational in the event of a large earthquake. These design requirements being recent, the Pierre-Laporte bridge and the structures located in the same axis were not designed according to these criteria and could therefore be seriously damaged if a major earthquake were to occur, thus leaving the two banks without functional link for emergency services. Added to the seismic risk is the wear and tear of materials: steel structures are subject to breakage associated with repeated traffic cycles, not to mention corrosion and other deterioration which, over time, reduce the reliability of the structures. The old Quebec bridge certainly does not have the capacity to absorb the additional traffic that would result from even a partial closure of the Pierre-Laporte bridge, which leads us to refer to “a second link” rather than ‘to a third link.
A choice dictated by topography
When designing a structure to cross a watercourse, it is often the topography of the banks which dictates the type of infrastructure chosen. For example, the banks of the St. Lawrence River along the axis of Highway 20 (Louis-Hippolyte-La Fontaine bridge-tunnel) are horizontal on both sides. If we had chosen to build a bridge there, the approaches would have had to be extended over a very long distance to respect the clearance required by the seaway and obtain acceptable slopes for trucks. This is why the choice of a tunnel for the Quebec project left us perplexed since the Trans-Canada Highway (A-20), at the chosen location, is 65 meters above the level of the river, requiring thus to build a very long tunnel in order to go down to the depth required for the structure to pass under the bed of the river. This is the opposite of the conditions that prevailed at the Louis-Hippolyte-La Fontaine bridge-tunnel.
A modern bridge
A clear height for navigation on the river of approximately 60 meters and an average level of the A-20 on the west side of Lévis of approximately 45 meters lead to an average slope of less than 0.5% between the axis of the A-20 and the high point of the bridge in the center of the river (4 km). This topography, favorable to the construction of a bridge, therefore encouraged us to push our thinking and explore places suitable for the installation of the structure. We therefore selected the Chemin des Îles axis as a potential route in order to briefly assess its feasibility, advantages and disadvantages. The crossing at this location is 2700 meters, imposing a clear span of 700 meters, well below modern cable-stayed structures which cross beyond 1000 meters of clear span. Such a work, designed with aesthetic considerations in mind, would become a signature for the Capitale-Nationale region.
Langqi Bridge (Fuzhou in China), 680 m clear span.
Courtesy photo
Among the advantages to be retained from such a route, let us cite, for the south side: an interchange to the right of the A-20 and Chemin des Îles already in place (with the necessary space for widening if necessary), the possibility of inserting incentive parking inside the interchange ramps (without expropriation), a Chemin des Îles already equipped with four lanes with mainly industrial residents. At the northern end of Chemin des Îles, agricultural land below could receive pillars spaced 100 to 150 meters apart which would have no more impact on agricultural operations than electricity pylons.
The recommended structure would be connected to Champlain Boulevard and would continue its route in a tunnel dug into the rock which would join Highway 440 (Charest Boulevard). All trucks exiting at Champlain Boulevard must necessarily head west, while those transporting dangerous materials must necessarily exit there. Stations (for buses or other modes of public transport) would be dug on either side of the tunnel tracks to the right of the east-west axis of surface public transport (René-Lévesque boulevard opposite opposite the Saint-Charles-Garnier college) and would be connected by high-speed elevators. This vertical link would be located halfway between Parliament Hill and the Sainte-Foy employment center, while being close to Laval University, thus optimizing travel times for users. This six-lane structure (three in each direction) would obviously include lanes reserved for public transport and carpooling.
A vision of the future
The abandonment of the Quebec-Lévis tunnel project opens the door to a reflection which should focus on the essential issue of public and economic security considering that there is only one viable highway link between Quebec and Lévis. We hardly dare imagine a situation where traffic would be interrupted between the two banks of the Quebec region for weeks, even months or years. This proposal seems to us to be both elegant, economical and technically realistic. Apart from the choice of the site, which will have to be the subject of in-depth studies, the need to build a new bridge in the Quebec region is in no doubt in our eyes.
Footnote:1 In Montreal, the Olivier-Charbonneau (A-25) and Samuel-De Champlain bridges were designed as “essential bridges” and would thus become the only passable links for emergency vehicles in the event of a disaster.
Daniel Toutant is an engineer who recently came out of retirement to supervise the construction of a new terminal at Saint-Hubert airport. He was responsible for the Highway 25 bridge project (Olivier-Charbonneau bridge).
Bruno Massicotte is a full professor in the Department of Civil, Geological and Mining Engineering at Polytechnique Montréal. In 2015, he carried out a pre-feasibility study for the Ministry of Transport for a road link east of Quebec.
