Q: It’s common now to see our Canadian friends gassing up their tanks, and then filling up multiple large plastic containers in the trunk. Is this safe? Is it even legal? Seems like it would be a real danger in the event of a serious rear-ender.
A: The answer to this question is way more technical than I anticipated, and to answer with confidence I’d need to be much more well-versed in hazardous materials than I currently am. With that disclaimer up front, I’ll give it my best shot. (And if any hazmat experts out there see something I missed or got wrong, let me know.) You asked if it is both safe and legal; those two answers are not necessarily the same.
The rules about transportation of hazardous materials come from the US Department of Transportation and are covered in title 49 of the Code of Federal Regulations (CFR), parts 100 through 199. (Washington state adopted the laws in the CFR, making it our state law as well.) If you’re hoping I read all 100 parts to find an answer to this question, I’m sorry I’ve let you down. That is some long and dry reading, and it mostly pertains to commercial transportation of hazardous materials. What we want to know is how much gas a regular person can stuff in the back of their SUV without needing a hazard placard and a commercial vehicle license.
As best I can tell, it turns out to be quite a bit. Assuming that the fuel is being transported in the typical five gallon container intended for gasoline, commonly called a jerrican (the term used by DOT) or jerry can, you’re allowed to transport 440 pounds of gas. With gasoline weighing about six pounds per gallon, that works out to roughly 73 gallons of gas, or 15 jerry cans. For most of us, the quantity of gas we can transport reaches a practical limitation due to the size of our vehicle long before we reach the limit in place by law.
But is it safe to stuff the back half of a car with plastic containers full of a substance known to burn rapidly upon exposure to a heat source? And I say “car” because while it would be much safer to transport jerry cans in the back of a pickup, my observation has been that most people are transporting gasoline inside the cabin of their vehicles, myself included. When my lawnmower runs out of gas, I fill up the jerry can at a local gas station, secure it in the back of our hatchback, and drive a few blocks home. It’s legal, but is it safe? Let’s recognize that safety is not a binary option; it’s a spectrum. Just getting into a car and driving on a public road is a risk. As we’ve talked about many times in these columns, focusing on safe driving behaviors reduces that risk.
When we talk about safety in conjunction with the kind of cargo we have in our vehicles, we’re really talking about how that cargo changes the outcome of a crash. If you knew you were never going to crash you could adorn the center of your steering wheel with four-inch spikes. Instead we fill the center of a steering wheel with a rapidly inflatable balloon, because none of us can be absolutely sure we’re not going to crash.
Where does gasoline sit on that crash outcome safety spectrum? It’s a flammable substance with an ignition point lower than the temperature of an operating catalytic converter or brake drums after hard braking. In a crash those cans could rupture, exposing the fuel to those heat sources and turning a vehicle into a giant fireball. It’s a situation where the minimal requirements of the law and your own level of risk tolerance likely don’t match.
If you need to transport gasoline, the best practice would be to put it in an approved container (and don’t fill it while it’s in your vehicle), leave some room for expansion of gasses, secure it so that it can’t tip or spill, and, if possible, stow it on the outside of your vehicle. If your motivation for transporting gas is to save some money, before you decide, do the calculation on what it could cost you in a crash.
Finally, I’ll leave you with a piece of trivia with which to impress your friends. Do you know where we got the name jerry can? The can was invented in the 1930s by Germans, who called it a Wehrmacht-Einheitskanister. You know that name was never going to catch on for the English-speaking crowd. The Allied troops used “Jerry” as a slang term for Germans, so when they saw the fuel containers they called them jerry cans.