Since the I-35W span fell down Wednesday evening, most of the news networks have been wall to wall with coverage, including special features, in-depth reporting, investigative assignments and the rest of the news hoopla.
For those of you living under a rock, a bridge fell down in Minneapolis, taking a big piece of the rush-hour traffic with it. Blood and guts? So far, five dead, perhaps a dozen missing and eighty injured. The do have live video of the bridge actually falling, from a security camera. It was a slow news week, so the three US majors came out in force, while the two cable news outlets are camping out on the banks of the Mississippi.
The outrage pot is being stirred. The US Federal government knew that the bridge was ‘structurally deficient’ and the Minnesota Department of Tranport (MinnDOT) was working on the bridge at the time it went down. The talking head brigade is speculating like mad that there is some massive infrastructure failure being covered up by the government at every level and we should all beware that the sky will fall shortly after noon on Saturday.
A reality check here: All bridges will fail. Bridges, regardless of size, or contstruction materials, are in tension and compression. They are machines that need maintenance, just like your car, or your lawn mower, or your bicycle.
Here’s a reprint of one from Road-Dave from October 1, 2006. http://road-dave.spaces.live.com/blog/cns!15F30E7F138DBB88!295.trak
Yesterday (Sept 30/2006), a 20 meter section of four-lane overpass collapsed and fell onto Highway 19 in the Montreal suburb of Laval, Quebec. The overpass, the usual concrete and steel construction was originally built in 1970 and fell 15 meters to the road below. At least two vehicles were pancaked under the slab. Five people were killed. Three vehicles and a motorcycle fell on top of the collapse, as the road disappeared from underneath their wheels. Six people who landed on top were injured, two are in critical condition. You can follow the story at www.cbc.ca if you want.
Stop and think about how many bridges you go over, or under, on your way to work, grocery shopping or doing the myriad things you do every day. Bridges, even the smallish ones that cross highways, or creeks are marvels of engineering. Thousands of cars, buses and trucks gallop along pounding the pavement every day.
To understand what bridges do, find a five pound bag of sugar or flour. Hold the bag in your hand and raise your arm straight out from the side of your body at right angles. Keep it there for five minutes without letting your arm sag, tremble or move. You are now, officially, a cantilever, one of the essential engineering structures that define a bridge. You can put the bag of flour down now. And stop you arm from throbbing.
The Laval bridge was only 36 years old. This is middle-aged for bridges. The problem is that in most of Canada we have winter. Winter means ice and snow on the roads, which, especially in Eastern Canada, means salt on the roads. Salt eats steel. To keep this corrosion in check, bridges get inspected, usually yearly, depending on the budgets.
Uh-oh I said a bad word: Budgets. Budgets for infrastructure have been cut to the bone year after year. Budgets for inspections have just about disappeared. Politicians have twin demons of getting re-elected, or doing what needs to be done. Getting re-elected means not raising taxes, or making sure that voters see what their tax money is paying for.
Bridge inspections and preventative maintenance are not things that a voter can look at and say "Yup. We need it and we’re payin’ for it, as we should." Nor for that matter is replacing or fixing the estimated 30 percent of sewer and water systems in most cities that leak. Pipes are underground and until you get raw sewage backing up into basements, or find a huge sinkhole in a road, the pipes might as well be on Mars. The electrical grid in this corner of North America is held together with spit, paper clips, gaffer tape and fervent prayer.
The ugly fact is that the Great Infrastructure Buildout of the 1950’s and 1960’s was a long time ago.
Did the Laval bridge collapse from a lack of maintenance? We don’t know yet. I do know that the inspection process these days is pretty rudimentary: "It is still there? Yep. Is it on fire but shouldn’t be? Yep. Passed. Next!"
Ontario is a good example of how not to do things. The TSSA (Technical Standards and Safety Authority) in this province is in charge of inspecting elevators. TSSA is a private company that slurped up the Technical Standards Division of the Ministry of Consumer and Corporate Affairs for the province. TSSA sets fees to perform inspections, as required under law. They are non-profit but are expected to cover their entire budget from license and inspection fees.
There are more than 43,000 elevating devices in Ontario. This includes escalators, passenger elevators, freight elevators and personnel lifts. There are 43 inspectors listed on the TSSA website for the whole province. This means each inspector, including the managers, has to inspect approximately 1000 elevating devices per year to make sure the old stuff is still safe and the new stuff is installed correctly.
By the way, there are 261 workdays in a year, assuming you get Saturday and Sunday off. Let’s call it 250 workdays a year, as folks do get sick, have to take training, statutory holidays, vacations, or to go to the doctor.
That means each inspector, having 1000 elevating devices to inspect, must do four a day. Two in the morning, two in the afternoon. I’m not counting travel time, lunch, buildings being closed, people not available, time to do the paperwork and so on. In the downtown core, this might even be doable, except the inspection time is basically 90 minutes per elevating device. Or, "Is it on fire and plummeting to the basement from the 28th floor with a load of lawyers? No? Passed. Next!"
To add to the impossibility of inspecting things, the TSSA in Ontario also inspects fuel standards, boilers and pressure vessels, upholstery and stuffed articles, ski lifts, power plants and amusement rides. I checked the number of inspectors for each category and at first glance the same names are in all the areas of authority.
How to fix infrastructure failures? First, it is going to cost a LOT of money that has to come from somewhere. Somewhere means you and me and our pockets. Second, we have to have some priorities as we can’t afford to fix it all. Someone has to look at all the infrastructure components and decide each year where the bulk of the money has to go to keep things from breaking down completely.
As an example, there is a rail bridge that crosses a major road here in Mississauga, not far from where I live. This bridge carries the GO Train, freight trains and passenger trains. If that bridge failed and fell across a major north-south artery, Mississauga would stop from a traffic perspective and a big piece of the GO Train metro system would be out of commission for several weeks.
Now, make that train a freight, carrying anhydrous ammonia, propane, new cars and bulk sulfur, which is a load I have personally seen on that line. The bridge fails and two dozen freight cars fall into the boulevard, cutting off traffic and burning for a while. You would have to evacuate most of Mississauga, which means 600,000 people have to go somewhere because of one rail bridge.
That is the hidden danger of infrastructure failure. The failure isn’t just one thing, it becomes, very quickly, several dozen things of ever-increasing danger and impact.
However, we don’t know what parts of our infrastructure are in the worst shape. We have no clue what bridges are merely looking old and tired and which ones are teetering on collapse from abuse, neglect or bad construction in the first place. Why? Because inspecting infrastructure is not a glamorous use of taxpayers’ money. It isn’t sexy like a convention centre, or a modern toll road. It doesn’t get the politician any publicity mileage whatsoever, therefore what will get cut first?
Bridges, roads, sewers, natural gas pipes, the electrical grid and all the other infrastructure things we rely on daily will last for several decades as long as regular, comprehensive inspection and repairs are carried out.
Will it eventually turn out that the bridge in Laval fell down because of a lack of inspection and general neglect? Again, I don’t know for certain, but I can make a well-educated guess. The answer is yes.
RoadDave 