Wednesday, March 11, 2009

Wide Load - What are they transporting?

Do you ever pass a truck hauling a strange looking trailer, wondering

“What’s in there?”

It's entirely possible that this is not a common thought unless you actually are in to trucks… I really have no clue what normal people are thinking.... :))

Anyway, regardless of that, I wonder sometimes as I pass some of these trailers, what they contain, so I wanted to post a blog on different types of trailers and cargo.


Every truck transporting some kind of chemical has a colored placard on the back of the trailer with a 4-digit number on it.

This placard identifies exactly what’s in the tank, that way if an accident and a spill occurs, emergency crews will quickly be able to identify what type of liquid they are dealing with. The numbers are designated by the UN or DOT and are referred to as UN/NA numbers or DOT numbers. The placard will immediately identify which type of chemical it is (explosive, corrosive, flammable etc) whereas the numbers provide more specific info on which particular chemical is being transported.

(This is actually a good piece of information to have, in case you are ever in such a situation and need to call 911. Informing the dispatcher of the DOT number & placard will be very helpful!)

One of the most common placards is this one for gasoline, I'm sure everyone has seen this one:

Here’s a placard for liquid oxygen:

I actually looked up what liquid oxygen is used for, because I see this transported a lot. Other than the fact that it’s really cold, I didn’t really know its purpose. Not a big shock to learn that it’s used in the medical industry, but the military and aircraft industry also use it as a source of breathing oxygen and it is also used in the space craft industry.

Just one of many, many chemicals that I have no clue what it’s used for, but the frequent sighting of trucks carrying liquid oxygen finally prompted me to look up what the big deal was :-))

Here’s a DOT placard I don’t think I’ve ever actually seen on a truck:
It means “dangerous when wet” (and yes, get your minds out of the gutter, I can see it splashing around there!)
It means that the chemical can potentially become flammable, toxic or explosive when paired with certain ratio of water. (Again…the gutter….get out…. )

I’m not going to post the entire list of DOT chemical numbers here, but if you are curious of what some of them are, here is a website with a complete listing of numbers and placards:

Drivers need special endorsements on their driver’s license to haul hazardous materials as well as to haul liquid bulk.

Ok, now let’s move on to other transports.

Here’s a trailer I never knew what contained:

Turns out these are for dry bulk transport, such as grain, flour, sugar, animal foods, wood chips etc. (Trailer photo borrowed from

Reefer trucks (nope, they don't transport stuff that's illegal!) – also known as refrigerator trucks.

These trailers have become pretty fancy. They are equipped with mechanical cooling systems, or some of them use CO2 to cool off the trailer, either in form of dry ice or liquid co2. I’m partial to this photo I found, as it has a cool-looking Kenworth pulling the trailer. Photo was borrowed from

Milk Truck refrigerated tankers transporting milk from dairy farms to the factory so you and I can enjoy our Oreo cookies the way they should be enjoyed --- thoroughly dunked in cold milk!

This last one is just a cool pic I found while looking around for funky transports... Looks like the entire road needs to be roped off for this bad boy to pass through. Not much passing room there!

Well, I could post a lot of photos of a lot of different trailers, but I just wanted to touch on some of the more curious ones... Should the urge be there to further explore the different trailers, there is an excellent trailer identification chart to be found here:

(Don't ask me how I find these I'm sure they'll welcome your visit!)


Odessa Coldiron said...

Reefer trucks have been a common sight on the roads nowadays, but people do not seem to know what they haul. Some truckers need to deliver perishable cargoes in perfect condition, so they use the reefer truck to help regulate the temperature. I think knowing what trucks are hauling can help avoid and prevent accidents with the other motorists.

spike spiegel said...

ok trivia time what chemical has the dot number 1005?