Water Under the Bridge: time now to protect the next one
By: Paul S. Hillier
Originally featured on The Suburban on 19 February, 2014
The Champlain Bridge’s deterioration occurred faster than anticipated because, as we heard, the corrosive effects of salt on the structure weren’t taken into account.
Most of us couldn’t help shake our heads (just a little) when we first heard this explanation. Meanwhile, engineers began to work on an immediate response that would ensure public safety and keep national and international trade flowing. Thus began the saga of the superbeam.
As stories of traffic delays now subside, as the assembly and installation of the superbeam appear to have been successful, and as the punditry continues, engineers are again one step ahead of us. This time there is the underlying, daunting question to answer: how do we mitigate against the effects of corrosion in the future?
One item being assessed is how to better make use of protective coatings that combat corrosion.
Many of us still remember watching rust eat away at the wheel wells of our first car and so have witnessed firsthand the exponential degradation that corrosion causes. My first car, a ’96 sedan passed down from my father, was rust-free for years. Yet, as soon as the protective coating in the paint first chipped away, within a year there was a thin rim of rust; six months after that the corroded rim had doubled in size, and three months after that I was shutting my door carefully, worried each time about the whole front end falling off.
This exponential pace of deterioration is a fundamental feature of corrosion that is researched at length by the world leading body of corrosion engineers, NACE International. If a material degrades 2% in the first year, the second year it may degrade 4%, and by the end of the third year, 16% of the material is corroded.
Our elementary school math should be enough to underscore the seriousness of this worrisome pattern; but what, then, are the tools at our disposal to mitigate against this danger?
Whether it’s Transport Canada, or a Crown Corporation entrusted with overseeing a major bridge, or a large-scale construction company, when big organizations such as these manage future risks it tends to involve frighteningly complex forecasting and modeling projections, executed by armies of expert risk managers.
And yet, at its most basic, even a $3-5 Billion bridge bears rudimentary similarities to my $2,300 car, where a comparatively small amount of money spent on protective coatings saves massive amounts of money in avoided repairs and lost productivity. However, it’s the application of protective coatings where this analogy ceases to be useful.
While the principle behind investing a small amount up front to mitigate against massive degradation due to corrosion later on is simple, it is anything but straight forward to execute an effective protective coating on a bridge wherein the structural steel in main span structure alone weighs some 10,000 tonnes.
The most significant challenges have been identified by the leading experts in the field: preparing the surface; selecting the correct number of coats; ensuring correct application, curing and drying under adverse conditions; as well as preventing mechanical damage sustained during the painting.
All of these, notably, are human factors associated with applying protective coatings.
On a broader level, the fundamental challenge stems from the fact that while there are organizations where leading engineers, scientists, and academics perform research into corrosion and protective coatings, the recognition of industrial painting as a certified trade is just a few years old in the United States. As Canada, lagging slightly behind, looks to develop a reservoir of these critically needed tradespersons, it will become increasingly important to consider how this resource should be used in the construction and maintenance of major bridges and other large infrastructure projects in this country.
As we look to the construction of the new Champlain Bridge that is anticipated to be completed as early as 2018, it behooves prudent policy makers to consider what role protective coatings and their proper application should play in this $5 Billion investment.
Paul S Hillier works with Tactix Government Relations and is the former owner of a ’96 black sedan.