Scales and weigh stations


The certified CAT scale.

Before I was a trucker, I always wondered what the purpose was of the weigh stations you see along the highway. I mean, obviously they were for trucks, but they were NEVER open. I swear. None of them. Ever.

Well, I can assure you, now that I’m behind the wheel of one of these big ol’ things and have to pay attention to these weigh stations, there are plenty of them that are open. My first few times through were kind of scary, too. There’s a DOT officer in that little building watching your every move. Are their stickers up to date? Is there any visible damage to the truck? Low tires? Burned out lights? Does the driver look tired? Are they following all the instructions? Scale speed limits? How about that seat belt? And are they within legal weight limits?

Well, I’ll get back to that because here’s the scoop. First we “scale,” which means we pay to find out how much we weigh so we can make any needed adjustments before getting to a weigh station along our route, where violations are given if you’re not within range.

So scaling – we get our trailer loaded at a shipper. I’ll use our last pick up as an example because some tricky stuff happened and it’ll be exciting. Maybe. Anyway…

We check in, wait for a few hours with the truck idling in 100-degree Washington heat, then finally get a dock door to back into. Ten minutes later we have a trailer full of bagged onions. (I wish I liked raw onions because that whole place smelled like one giant onion.)

Next I head in to get the bills. I sign them saying the shipper both counted and loaded the freight, I head back out, pull away from the dock, get out and secure the load with a load lock (a long metal bar that keeps the palettes from shifting inside the trailer), shut the doors, make sure the reefer temperature is set for 55 degrees as requested, then get back in the truck.

Most shippers we’ve been to don’t have their own scale, but this one does. And there’s no charge to use it. Bonus! Sometimes you pay like five bucks.

When we weigh, we need to know four weights:
Steer axle (the front set of tires on the truck)
Drive axle (the back tires on the truck, under the front of the trailer)
Trailer axle (tires in the back of the trailer)
Gross vehicle weight (total weight of the whole, loaded rig)

To be legal, the weight you’re looking for can differ by state, but as a general rule, you’re looking to stay under these numbers:
Steer axle: 12,000 pounds
Drive axle: 34,000 pounds
Trailer axle: 34,000 pounds
Gross weight: 80,000 pounds

I roll up to the scale, just getting my steer tires on. It reads 11,820. Next I add my drives to that, so combined I get 46,340. Then I add the trailer axle, which gives me my gross weight – 82,780 pounds.

Before even doing any math to get my individual axle weights, this is where I stare for a moment and say to myself, “Crap. That gross is almost 3,000 pounds over.” There’s no getting around it. Gotta back in again and get some of these stinkin’ onions taken off. I do that, also having the forklift driver shift everything a little off the drives. It was a bit heavy, and when you fill up the fuel tank, it gets even heavier up front. All these things have to be considered. We even have to be sure one of us is in the bunk. 150 – 300 pounds can put us overweight if we’re in the wrong spot!

Okay, back on the scale. After a little math, I get these numbers:
Steers: 11,720 – good!
Drives: 33,730 – good!
Trailer: 34,160 – over… crap.
Gross: 79,610 – at least this one’s good this time!

So now what? We have to fix the weight on the drives. To do this, we slide the tandems – the trailer can slide forward and backward on the trailer axle in back. (Next time you’re cruising down the highway, pay attention to the back tires in comparison to the end of the trailer on a few trucks – they won’t be in the same place on every truck. This is for custom weight distribution.)

Anyway, moving the trailer just a few inches one way or the other can change the weight on all of the axles. It works kind of like a teeter-totter. The further towards the front of the trailer the tires are, the more weight that sits on the trailer axle. The further towards the back of the trailer they are, the more weight that sits on the drives. So I need to move them back – but just a little bit. It takes me a couple of tries, and I find that I’m stuck between two positions. On one, the drives are over, on the other it’s the trailer.

Adam and I discuss options. We’re SO close. Maybe a DOT officer won’t care about 100 pounds. But maybe he will. That’s a violation and a fine. Both our record and our company’s record gets a ding for it. I don’t want to take the chance. We joke that Adam could lay across the dash when we go through weight stations. We figure we can leave our fuel below 3/4 of a tank to help. Strategies…

Then Adam says, “that’s pretty low compared to what our steers normally are. Let’s get a CAT scale and see what it says.”

Our steers are almost always right up to 12,000. And shipper scales, like the one we were currently using, aren’t “certified.” The CAT scales at truck stops (giant yellow sign with a black cat logo) are certified, meaning they’re as accurate as we can get. In addition to that, if their scale tells us we’re legal, and we get cited for being overweight, our records still get dinged, but CAT pays the fine. It’s their little guarantee.

There happens to be a CAT scale down the road – most importantly, it’s BEFORE we cross any weigh stations. I say a prayer and we roll on. We pay ten bucks and get our official ticket. Holy frickin’ crap. We’re JUST legal! Whooop! After eight hours at the shipper, removing 3,000 pounds of onions and shifting them around, sliding tandems three times and scaling four times, I am SO happy I uncontrollably laugh out loud. This more accurate scale says we are good to hit the road and roll through weigh stations without worry. Seriously the best news of the whole day!


Our legal weights! Ohmygosh. YAY!!

So that’s scaling. Now we hit the road and go past a weigh station. If it’s closed, we roll on by. If it’s open, a couple of things can happen. Some weigh stations scale you while you’re on the road (weigh in motion). If you have Pre-pass, which we do, it will beep slowly about five times and a green light will blink if you get a bypass. Yay for green lights! They’re the BEST! That means we don’t have to pull in. We just keep going.

But then sometimes it beeps fast five times and gives you a red light. It doesn’t necessarily mean something is wrong, but it does mean you have to pull in. There are a lot of things you have to pay attention to now. There’s usually a posted speed limit for the scale, first of all. I hear that quite a few speed violations are given out at weigh stations. Seat belt violations, too. Drivers unbuckle to reach for their paperwork or something and get pulled aside because of it.

Anyway, so you pull up to the DOT shack where there is a scale. They’re all a little different so you have to pay close attention to signage and instruction. Sometimes you stop before rolling on, sometimes not. Sometimes you stop for each axle and sometimes you roll on through, usually at 3mph. After driving over the scale, there will usually be either a red/green light or a marquee sign with instructions. A green light or instructions to continue on are what we want here.

I haven’t gotten a red light at the scale yet, but if I’d have left those 3,000 pounds of onions in my trailer, you can bet I would’ve have had the experience!

If you’re overweight, if they see something out of place, a broken light, if they think you look fatigued or even just randomly, they can pull you aside for an inspection. Inspections are a whole other story. Probably longer than this one! We’ve only gotten pulled aside once so far as a team, but that’s because there were two lanes to go around the DOT shack. There were two lights with arrows indicating which direction we should go. Neither light was lit up. we took the wrong way. The officer seemed quite irritated and asked us to pull around and bring in our paperwork. Adam was driving, so he parked and brought his papers in. The officer gave him a level 3 inspection, which is only a driver inspection – hours, paperwork – things like that, which he passed no problem. We run electronic logs (another whole story in itself!) and we simply don’t run illegal, so no worries. He got a clean, quick inspection and we were on our way. At that point, they can send out an ispection officer to look over our truck with a fine tooth comb.

So that’s the difference between simply scaling the truck and going through weigh stations. There is so much more responsibility with truck driving that I could’ve ever imagined before I started with this career. It’s a pretty big job, but it’s fun. When things go right, anyway… like that CAT scale ticket.

Tonight I love green pre-pass lights. I seriously smile every time I get the slow beep-beep-beep-beep-beep and blinking green!


I still don't quite know what the yellow is for, but the red and green ones work. Green rules.

Thanks for reading and being a part of my journey!

With love,
Toots Magoots
(Robin Grapa)


10 thoughts on “Scales and weigh stations

  1. Great blog topic! I work in the transportation biz..not as a driver but as a coordinator. This was extremely informative.

  2. Went through one today, first time since I got hired a week ago. Had green lights a few times before but nothing out by the road today. Sign said all truck pull in, so I did, saw the arrows change a few times add I slowly pulled in(prolly the truck on front of me), but I saw the next sign and it said follows arrows so I looked up as I passed by and the first one was green going forward, then the next was green going right so I moved right to follow it around. Thought maybe two scales or something had no clue, but it took me back out to the highway, it was rush hour, so I was nervous and didn’t know what to do but go on. No one ever followed me though probably due to traffic. I was going slow but don’t know my exact speed. So I guess I wait to find out anything, that is the name of the game isn’t it, hurry up and wait?

    Still confused though, I guess they had a scale pulling in. We only had roughly 2000 lbs though. So I know it was not over loaded, just don’t know if I was supposed to stop, I didn’t want to, I was a little tired after driving all night. First week, they didn’t give me much training on it. Or tolls, did not realize the little box was for tolls as well. The toll attendant there was not too happy. He asked for a ticket when I pulled up and I said I had no clue, asked how much it was he said “you didn’t get a ticket” I said I didn’t know what he was talking about, I just know my company covers tolls. I thought we paid and they reimbursed. Evidently not. I’m really having second thoughts about this, because I can’t even afford tolls let alone any violations for something I don’t know anything about.

    Words of encouragement may help. I might look for something else though.

    Thanks for reading.

    • It sounds to me like you did everything right at the scale. Just follow the arrows the best you can. I’ve had some weird situations before, too, and my trainer always said, “if they (dot) wants you, they’ll get you.” He said he once missed a scale because he was passing another truck, and the dot had him pulled over before the next exit. So if nothing happened, you’ve got nothing to worry about. And if they do ever come after you and pull you over, just be calm and courteous. Ask kindly if you did something wrong and if so, just explain that you were confused. Most of the time they’ll be understanding.

      I’d say keep at it. Tolls and scales – things like that – can be intimidating the first few times through, but it gets easier and you keep on learning. You’ll get better and more confident with time. Just be patient. :)

      • Thank you. It was rush hour in a huge city though. I was almost late due to the stop and go (slow) traffic. But already on another run. That’s good I guess, been busy since I started. Still can’t sleep. That bed is hard. Going to be another long night.

        Thanks again though.

        We’ll see what the pay checks are like I guess I started at the end of the week so after the physical and drug screen and only to small runs before end of pay week my check was negative almost 2 bucks.

  3. I always think that there are never weigh stations open, much like you used to think. Good to know that’s not the case! It’s interesting to me to see all the different measures you need when you use the scales. Obviously it’s a problem if you’re over weight, but is it ever difficult to simply get the numbers accurately?

    • Yes, it can be tough to get the numbers right. You can be under gross (80,000 pounds), but depending on the way the trailer is loaded, you might have to much freight up towards the front and your drive axle will be overweight. And if it’s close to the 34,000 pound limit, you have to consider how full your fuel tank is, because if you fill up, it could put you over, too.

      We’ve already had quite a few situations in which the shipper had to rearrange the load because there was no way to make the axle weights legal the way it was loaded – always a bummer for everyone!

  4. I’ve always wondered how weigh stations work, and if you have to stop at every one that you pass. Being scaled with the PrePass while driving by sounds much nicer than having to stop and be weighed and inspected each time. Thanks for giving me an idea of what driving a truck is like. I hope you always get the green light!

  5. My 8th grade math/science teacher gave us a truck scale problem. If we had a load of 50,000 lbs of canaries and we got half of them to fly around in the trailier when we went over the scale, what would the weight be? Can you give this a try and let me know.

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