What Is Still (Very) Good at Turcot

What Is Still (Very) Good at Turcot

What is still (very) good at Turcot.

By Pieter Sijpkes

In this chapter alternatives to the two main parts of the plan for the Turcot Interchange and Turcot Yards put forward by the Ministère des transports du Québec (MTQ) will be outlined.

These counter-proposals were developed this winter at McGill University when my second-year architecture students and I looked into the opportunities and problems related to the Interchange and the Yards.

The chapter is divided into four sections: a summary; a counter proposal for the repair (rather than the proposed demolition) of the Turcot interchange; a counter proposal to modify the MTQ’s plans to reduce the Falaise St Jacques to a highway embankment and; a final section in which all Montrealers are encouraged to visit and survey the Turcot area in person. belvedere bottom up tif

Proposed Entrance Pavilion and Belvedere, overlooking the Turcot Interchange and Yards from Terry Fox Park.Designed by student Anne-Marie Nguyen.


This stage in the course of events surrounding the Turcot Yards project can be compared to the time when things went wrong with the Apollo 13 mission.

The pivotal moment in that mission came when its crew was asked by ground control to focus on what was still good on the ship rather than on what went wrong. We are at a similar pivotal point in the 40-year saga of the Turcot Interchange and Turcot yards, and so I ask “What is still good at Turcot?”

The MTQ project is informed by two major decisions, both of which should be reviewed from an Apollo mission perspective. The first decision is that the many spans of the Turcot Interchange (and the associated d’Agrignon and de la Verendrye sections) should be torn down and replaced by "lowered" structures.

I argue that a repair-in-place option should be revisited. Repair-in-place of the viaducts would not require expropriation of housing units, would preserve the many hectares of useful land below the structures, and would eliminate the need for an endless series of berms.

The second MTQ decision is to move highway 20 and the CN tracks towards the Falaise St. Jacques. This plan is reckless. The highway and the tracks are fine where they are (straight and on grade) and howthey are (in good condition). There is no need to “open up”at great expense 100 hectares of developable land that are already opened up. Instead, the Falaise St. Jacques could be widened into a real and unique linear park, and it and part of the restored St. Pierre River could be protected from highway noise by a simplelandscaped berm. The remaining land could then be used for what it is well suited—train shunting and maintenance, and truck-rail transfer activities. (This would have the additional humanly beneficial effect of making neighbourhoods like Point St. Charles and Cote St. Luc less noisy as such rail activities were moved away from them.)

Unlike the single plan presented by the MTQ, the similar Alaskan Way Viaduct case in Seattlehas for years seen experts and the general public alike rigorously debate as many as ten options. A repair-in-place option was recently given new life with the commission of a $150,000 independent study from the prestigious engineering firm T.Y. Lin.

The lives of the Apollo 13 crew were saved by focusing on what was still good on their craft; the environment and the pocketbooks of Montrealers will no doubt benefit from a similar change in focus in the MTQ Turcot strategy.

Counterproposal 1

The ups and downs of the Turcot Interchange: a repair option outline

Turcot bottom jpg

Elevation of a typical Turcot span after repair

Graphic by Stuart Kinmond

The construction of the Turcot interchange coincides with my arrival in Montreal in 1966. I saw the concrete being poured; I rode across the interchange in a borrowed car the day it opened.And there was a lot more fresh concrete curing in Montreal at that time. Luigi Nervi's Place Victoria had just been declared the highest concrete high-rise in the world, Ray Affleck's Place Bonaventure, the first real mega-building on earth was being denuded of its formwork, and MoisheSafdie's boxes of Habitat '67 were just settling in on top of each other.
The TurcotInterchange looming high above the black landscape on its hundred-foot stilts, lit by two parallel, continuous bands of built-in fluorescent lights, fit very well into this brave new world.
However, the "alien landing lights" were gone after two years (aluminum wiring and aluminum casing do not last long when splashed with salt water in winter). And, the concrete of the interchange soon showed signs of distress.

Reinforced concrete, when soaked for prolonged periods inwater (salt or not) will absorb it to a certain depth. If this depth is more than the thickness of concrete covering the reinforcing bars (two or three inches), these bars start to rust. When steel rusts it expands in volume about ten times. Once water gets in, "rust inflation" will soon push away concrete covering it, exposing yet more steel to the corrosive influence of salt water. ("Spalling" is the technical term for this process).

The Turcot interchange was very tightly designed—there are no shoulders, so snow cannot be pushed to the side to clear the road, and lots of road salt has been used to keep the easily frozen, exposed spans navigable. The brine resulting from this process has flowed like a river down the sloping roadways, not easily finding drains. Expansion joints (planned "cracks" in the structure to allow it to expand and contract) have formed virtual waterfalls, and the water has also found its way into many unplanned cracks in the structure. The deck of the Interchange is made up of eight feet deep by eight feet wide, hollow "caissons." In some places as many as seven caissons are found side by side. When finally inspected through newly cut access-holes, some of these hollow caissons were found tocontain significant amounts of infiltrated standingsalt water. If you planned to weaken a concrete structure without much effort, this is the way you would do it.structure turcot jpg

Cross section of part of the Turcot interchange
Over the years many efforts have been made to repair flaws in the Turcot Interchange. The built-in lights were replaced by standard pole-mounted lights; the spalling concrete was patched up over and over again. The caissons were drained and the roadways above were repaired many times. But the expansion joints remained problematic and the spalling of the structure became so pervasive in recent years that the concrete was no longer patched; instead, it was in many places (for all to see) covered with two layers of mesh (one coarse layer covering a fine one) to prevent lumps of spalled concrete from falling onto people passing underneath.

After the collapse of the Concordia Bridge in Laval a few years ago, worries about the structural integrity of the spans brought about almost desperate measures. Anchors were installed from the top of some of the caissons to the bottom, in the hope of preventing structural disintegration and possible collapse of the caissons (particularly the outer ones, and mostly at the expansion joints). The Interchange is monitored 24 hoursa day now, at a cost of several million dollars a year, so that stop-traffic, emergency structural repairs can be quickly made.

Yet, I think the Turcot Interchange should be fixed rather than torn down. Mine is a minority voice. The engineering community has decided that tearing the structure down and replacing it with a system of on-grade access ramps and a few overpasses will solve "the problem" the same way the Pine-Park interchange problem was solved. But a replacementoperation will be complicated, costly, and damaging to the environment.

As with a heart-lung operation, the system has to be kept fully functioning while the replacement operation takes place. The volume of concrete debris created would be huge, and 200 apartments would have to be demolished, which would squeeze the last breath from the small enclaves left after themassive demolitions required by the initial construction. The free space now existing underneath the overpasses will be cut up and made useless by the earth berms. (For a preview of what is planned, the Anjou interchange is offered as a model.) Finally, the estimated cost of the whole operation stands at 1.5 billion dollars. I am always wary of figures like 1.5 billion. Why not 1.6 or 1.4? Because nobody really knows what the final cost will be! Look at the Notre Dame East reconstruction. Two years ago it was estimated to cost 750 million dollars. Last month, without a spade having touched the ground, the cost has gone up to 1.5 billion dollars. Need I also point again to the sad saga of the Super hospitals?
There are two schools of thought in construction: the conservative school (of which I am a member) and the more radical slash-and-burn school. I use the word "conservative" here as it was used during Apollo 13, the movie. When faced with possible disaster, Apollo 13's mission control director Gene Kranzsaid,"What do we got on the spacecraft that's good?" This attitude helped save the lives of the astronauts. Taking a comparable stance toward fixing the Turcot will surely save a lot of grief and an incredible amount of money. Again, the "slash and burn" approach to hospital renewal (now over ten years in limbo) comes to mind, and it is interesting to see how reality has forced the McGill University Health Centre to include a renovated Montreal General Hospital building in its original tabula rasa plan.

There are many precedents for major infrastructure projects that have followed the conservative "modify rather than demolish" route. They are listed in one my links in the index. An important one for all to see is barely a mile away from Turcot and goes back over a century. The original Victoria Tubular Bridge was built in 1859 in the form of a single wrought iron tube on 24 ice-breaking piers. A single train track ran through the tube. Towards the end of the century this arrangement was woefully inadequate, and a new bridge was needed. By reusing the 24 piers, and using the steel tube as a scaffold, the current truss- structure came into being. According to the Montreal Herald of the time:

victoria bridge clip nyt cr jpg

$6,813,00 for the original 1859 bridge, and $2.000.000 for the 1897 one. It seems that re-use certainly paid this time!

In the link section at the end of this chapter there are references to several other large infrastructure repair andreuse examples.

My proposal for the Interchange consists of three ideas.
One, public safety has to be put first and foremost; a collapse like the Concordia Bridge must of course be prevented. The solution is to reinforce all or most of the spans of the (until now) self-supporting concrete deck by deep steel beams. A triage should be done, to identify spans that need extra support right now, those that can wait, and those that don’t need reinforcement.(This process is common in earthquake country: at a Tokyo train station viaduct I recently counted four different structural systems within five spans; the motto there clearly was: repair if you can at all costs.) Fortunately installing supporting beams is quite easy in most places because the Interchange is elevated above grade as much as 100 feet, leaving ample room for a new, prefabricated structural beam (or even an arch in the long span cases) to be inserted, without obstructing passage below. Once the original spans have this additional support, there is no longer any worry about structural collapse even if part of the caisson structure has deteriorated. (The Concordia Bridge collapse was due to an unusual "lip joint" that was badly designed, badly executed, and not maintained for 40 years!) The Turcot is a continuous, indeterminate structural system; this system has a lot of redundancy in it, which, combined with the extra support system underneath will guarantee ample structural strength for many years.

Turcot top jpg


Model and section of repaired Turcot span (cross-bracing with castellated beams not shown in the section for clarity)

Detail of the existing concrete structure supported from below by a new grid of man-high steel beams.

If added measures have to be taken to bring the structure up-to-date for earthquake resistance, this is the time to do it. In my references below I give links to many examples of retro-fit earthquake proofing.

Two, the roadways on the deckand the expansion joints will have to be redone. This process should ensure excellent drainage is achieved to minimize water infiltration. In addition, the minimum amount of salt and the maximum amount of harmless grit should be used in winter from now on to keep the roads navigable. It is said that it is impossible to have waterproof expansion joints, but every time I drive over them on Rene Levesque in front of Place Ville Marie, I realize that there is no water leakage in the underground city below. If it can be done there it can be done at the Turcot. The spalled surface concrete now so evident should also be repaired using the latest techniques.

Third, the maintenance of the structure should rigorous and continuous. Following the practice of Gothic Cathedrals (where maintenance structures were built into the fabric at the time of construction), the new under-deck support structures that I suggest, would serve as platforms for future maintenance of the concrete deck without the need for expensive scaffolding every time a flaw becomes apparent. The steel girders portrayed in the illustrations are of the castellated type, which feature large openings in the web, allowing easy access by maintenance personnel.

It is my view that taken together these three measures will allow the interchange to continue to function for many years to come. During this time there will be opportunities to improve and extend the public transit system with projects like the rapid rail line to Trudeau airport, thus relieving some of the pressure on the Interchange. Cars, on average, have become smaller and lighter since the Turcot was built, so the rather tight dimensions of the roadways are actually becoming less onerous as time passes.
Finally, one great advantage of the methodology sketched above is that it can be completed in steps, starting tomorrow. These steps can be small and we can learn from them as we go along; costs can be tightly controlled during a step-by-step repair of the system, and; no interruption of traffic and no displacement of people will be required.

Counterproposal 2

A case for the expansion of the Falaise St. Jacques into a linear park.

The MTQ‘s plans call for the realignment of the CN tracks and autoroute 20 close to the Falaise St. Jacques. Public pressure against this move has recently led them to change their original plans: the location of the right-of-way for the highway and the tracks are now planned to clear the Falaise by 15 meters rather than being right up against it. This change in alignment makes the cost of relocation even more onerous when calculated as a charge per hectare of land. My student group has focused their efforts on the design of the expanded ParcFalaise St. Jacques.

One intriguing idea brought up by them was that the Park could accommodate functions that are not available in any of the other Montreal parks, such as horse riding, mountain biking and orienteering. One student proposed in some detail a steel cable suspended from a tower in Terry Fox Park that would allow visitors to slide down to a pavilion at the bottom, across where rue Pullman now runs and where she had restored the St. Pierre river. It was wonderful to see these ideas bubble up, and it reminded me of the time in the early 70’s, where, as students, my study mate and I proposed a green park along the banks of the Lachine Canal (including a bike path) to incredulous critics.

turcot 2 jpg

MTQ proposal to move autoroute 20 and the CN tracks.

The new ParcFalaise St. Jacques which includes the Falaise proper enlarged by a green strip (including Rue Pullman) and a bicycle/foot path along the top of the Falaise.

Terry Fox Park, an excellent location for the construction of an access pavilion towards the new “ParcFalaise St. Jacques”.