Hot takes for clearing the Ambassador bridge
Over the last few weeks a huge political crisis has been developing in Canada. At the beginning of it all there was surprisingly little media coverage but when large scale protest action stated blockading various places there was a bit more media coverage but there was a whole lot more action on social media about this. A lot of people are writing about this already so I may or may not end up commenting on it at some point. Unfortunately it seems that many of the parties involved have little interest in de-escalating the situation so I expect this crisis to continue on in some form or another for some time. Something about this whole situation doesn't seem right, the lack of attempts to de-escalate the situation in particular strikes me as completely counter to the sort of culture I witnessed when I lived in Canada.
During this whole episode I'm once again reminded of something I saw in the middle of the great toilet paper panic of 2020 which is that many people have no fucking idea whatsoever how modern logistics actually work despite so much of modern life depending on it. Of course in this social media era we live in the presence of a lot of trucks at a political event now is enough for many to instantly consider themselves as logistics experts with a need to tell everyone their hot takes about it. Truck based logistics is basically completely essential to the modern economy and disruptions to it cause an enormous amount of problems, this is one of the reasons the blockade at the Ambassador bridge was so impactful, a lot of trade occurs via truck transport that goes over that bridge. In normal times people pay very little attention to logistics despite its enormous impact on modern society. This might not annoy me so much but we have had many months of supply chain issues now and the amount of quality information on the situation is staggeringly low. Despite historic port congestion, increased shipping delays, huge inflation in transport prices, and even looting of moving trains for the most part people are still taking logistics completely for granted. Because I've spent some time working in logistics and warehousing this situation unfolding over the last few years has been frustrating to witness to say the least.
During the Canadian political crisis the Ambassador bridge that connects Windsor and Detroit on the USA/Canada border was blocked by a number of trucks protesting against various mandates in Canada that have been impacting the trucking industry. This has been a very charged topic and in some senses has reminded me of the Dreyfus affair because of the huge amount of division this has caused. Much like most politically heated topics you start to see a proliferation of people motivated by politics who start commenting on the situation without knowing anything about the industries they are commenting on. There were a huge number of absurd comments made about how to deal with this situation by armchair commentators. One of my favorite immensely ignorant hot takes was the following suggestion to clear the blockade:
This suggestion is from a full professor at Harvard.
I'm reminded of something that George Orwell said, "There are some ideas so absurd that only an intellectual could believe them." I mean the obvious thing here is that if you have trucks on a bridge then removing the fuel and tires isn't going to make it easier to move them and clear off the bridge. The utter stupidity of this very public comment does make me ask some questions about how this person got tenure.
For starters even just attempting to slash the tires is far less easy than someone might assume since slashing tires that are filled at high pressures is an incredibly dangerous thing to do. And truck tires are filled with a high pressure, and there's more to the tire pressure than meets the eye. When I've been working on building sites I've used a framing nail gun that will drive nails deeply into structural hardwood, this system runs off compressed air, the compressor can be set to run 70-120 PSI. You feel the power of high pressure air when using equipment like this and you take it real serious. Know what else has a pressure of 70-120 PSI? Truck tires. Effectively if you slash a high pressure tire with a knife you are creating an ad-hoc nail gun with a sharp blade that's going to be moving in your direction at a high velocity. Still seems like a good idea?
That clip that was going around a few years back where someone cuts his arm off by accident when slashing a big tire resurfaced here (the extreme amount of pressure released basically throws the knife through his arm when he cuts the tire). Its rather graphic so I'm not going to share it but you could probably find it if you wanted to, wouldn't recommend watching.
TLDR Summary: slashing high pressure tires is super dangerous so don't do it. You have to not have practical experience with these sorts of things to even consider trying.
OK so what about removing the fuel? Removing the fuel is easier than removing the tires via slashing them in the middle of a crowded bridge. But the painfully obvious part of all this you might be thinking is if you get rid of the fuel and the tires then how are you going to move the trucks? Basically if you aren't the sort to do mental gymnastics and mental contortions to back your pre determined political position then you'd very quickly realise that the best way to move a truck is to move it under its own power. You know actually driving it the way it's supposed to be driven. But instead of the rather simple idea of just moving the trucks the way they are designed to be moved you'd see a number of people coming up with all sorts of weird ideas that were wildly detached from reality of how to move them. One of my favorite categories of absurdity were suggestions to get helicopters to lift the trucks off the bridge.
Normally going into the details of this would seem to be an exercise in pedantry, but when people are actually seriously suggesting trying something then it becomes important to show why the laws of physics are not in favor of it. A Sikorsky Skycrane is one of the more powerful helicopters out there and it can lift 9100kg of payload. Let's just say for the sake of the exercise here you just have fleet of these ready to go at short notice and you magically have attachments to pick up the items, what could you do move with it? For comparison weight maximums for semitrailers on the interstate highway system is 20000lb or 9100kg per axle. So clearly you couldn't lift a fully loaded trailer with one of these helicopters. But what about splitting the cab from the trailer and lifting the various parts separately?
In our current era of standard containerized shipping we have rather ubiquitous 40ft containers, which have become a standard size. These are the things that you are now seeing stacked in huge piles at ports in the world. They are also what you frequently see on truck trailers. There's standards for these and the maximum weight of such a container is 30480kg when fully loaded. An empty 40ft container will frequently weigh somewhere around 3750kg, so that could be lifted provided it was empty and provided there was access, if the containers were full then emptying out the containers would be a pain but it could likely be done even if this was very slow due to the lack of loading ramps, space and equipment.
What about the just lifting the cab?
Semi trucks without a trailer in North America can weigh between 10000 and 25000 pounds when empty. You'll quickly notice that 25000 pounds is already more than the max payload of the Skycrane. So already we have some trucks that will be too heavy even when empty to be lifted by one of the most powerful helicopters in the world.
TLDR summary: Trucks are heavy and helicopters probably can't lift as much weight as you'd think[^1]. Also you'd have to find the helicopters and a skilled crew from somewhere to even be able to attempt this, and even if you could find the equipment and the operators it would likely be a really slow process compared to driving the trucks off.
Now on top of this we haven't actually addressed the question of if it's even feasible to lift anything heavy at all from the deck of the bridge. The Ambassador bridge is a rather large suspension bridge, with the longest span being 1850 feet or 560m. This was the longest suspended central span in the world when it was completed in 1929. This means that the bridge has been designed with huge steel cables from the towers to support the span. A picture gives a really good perspective on what the bridge looks like with the Trucks providing a sense of scale, notice those big metal suspension cables on the sides, those would really mess up a helicopter:
Getting to the middle of the span might be possible because the suspension cables may not impede a helicopter in the middle of the bridge. But near the ends those towers are more than 100 feet high and form a fence of steel cables so it's going to be effectively impossible to land a helicopter anywhere near them. I suspect it would not be all that easy to attach a heavy load that's over a hundred feet lower down, for starters weather conditions would have to be good then you'd need to get thick cables that could support that much weight. Picking out these cables would require looking at various specifications to see what sort of loads they could sustain and how heavy they could be, you get the idea.
TLDR summary: it's much easier to drive the trucks off the bridge instead of trying to airlift them off a particularly difficult terrain.
While there were many, I'll go over one last comment expressing complete ignorance of engineering made about this same situation:
Oh My! Clear that bridge, it could collapse with all that weight resting on it. Just keep it empty and move up as needed. It would be a shame if it fell with them all on it!
Bridges are especially well engineered in the western world these days. In recent decades it has been very rare in western world, or anywhere that can apply modern engineering1 principles to see for bridges collapse just due to the regular load on them. Keep in mind the bridges are explicitly designed not only to hold the load that could be on the deck but are engineered with large margins of safety to make sure that the structural integrity holds up. Inspection checks are made to check that bridges are capable of handling the capacity and they tend to get closed if they aren't up for it.
TLDR summary: Bridges in the western world aren't going to collapse just because they have their regular loads sitting on top of them. This is because we have a system that allows engineers to build bridges based on actual engineering principles and actual engineering principles deal with margins of safety in a very methodical manner.
I think these hot takes show a great practical example of how central planning when done without expertise opens the door to tremendously bad ideas being attempted. People who think they are acting in the best interests of everyone can be tremendously dangerous when they act from a position of ignorance. People who are far removed from the practicalities of particular tasks tend to lack enough information to make good decisions, and they might lack information to the extent that they aren't even aware of how ignorant they really are. Good intentions are insufficient to get good outcomes. Unfortunately in the modern world many people think they know how things work because they have had a cursory exposure to them.
"For every complex problem there is an answer that is clear, simple, and wrong." -- H. L. Mencken
As someone who has had a career working with engineers to me one of the most scary aspects of the blockade at the Ambassador bridge was the ease at which so many people were happy to use engineering as a political football to push the political agendas they wanted. Notably almost none of those people were actual engineers. Furthermore I saw angry reactions to engineers who were making comments based on actual engineering from pundits that were throwing around political comments that were claiming to have some basis in engineering. Nothing good comes out of the politicization of the practice of public engineering works. I see why people get tempted to try bring politics into engineering but really there's a lot of reasons you don't want to go there.
[^1] Trucks carry heavy freight and because of this the components used in these vehicles require materials that can handle the weight of the freight they are carrying. Many of these materials are heavy and while there are some lighter materials available you start to have to spend a lot more money on those which changes the costs to benefits ratio. Looking at space based industry gives a window of insight into the engineering and economics of strength to weight tradeoffs in designs. Many of these designs are only possible when there's a large amount of budget available explicitly for the purposes of reducing weight because the materials are very costly. Reducing weight is not cheap and unless you've studied material sciences it's not always intuitive either. A crucial part of forming a good intuition for these things relies upon understanding the numerous engineering tradeoffs that apply in this space. In terms of shipping things it might seem inefficient to have heavy trucks but it's actually quite hard to carry bulk items efficiently other ways without the costs blowing up in other areas. Because the whole point is to carry heavy things from place to place you have a floor on the amount of weight. Unfortunately a lot of people are unaware of the constraints that force tradeoffs to be made and you see the thought process flaws that occur from this when you see comments that appear to not take any of these tradeoffs into account. Seeing people suggest moving trucks with helicopters reminds me of the misplaced hype in drone shipments of packages. I think both have a similar flaw which is that moving things by air takes a lot more energy than rolling them, and the people who are hyping things don't understand the physics of this.
In the modern world one of the largest risks to the successful application of engineering principles to public works is actually political pressure. If people can be pressured to just do whatever political power wants them to do it tends to lead to structures that are built less well and less safely. Cutting corners and corruption often tends to result in poorer construction quality for each dollar of expenditure. By normalizing people using engineering as a political football there's enormous follow on consequences that many people don't see. I like that I can travel around and have really good faith that when I drive over a bridge it won't collapse under me. I have that confidence in locations that allow engineers to without fear or favor apply engineering and safety principles, even when it would be inconvenient powerful interests in the short term to do so. The benefits to this arrangement on the longer term are so enormous that in the previous few decades in the western world started to put things in place to ensure this continued. With this adherence to engineering standards being eroded in response to political expediencies we see more than just cracks in the system emerging, we start to see very real structural cracks popping up in many buildings. ↩