How high is that overpass -- REALLY?!

[Oldyeller]

I've been thinking about bringing my skoolie to my driveway for a couple weeks before winter hits here in New Jersey. Given my state of paranoia about driving it, even though it's 'legal', has me wondering if I'd be better off driving it the 20 miles across I-80 or taking the backroads. The reason I'm even having this internal debate is due to 2 overpasses on the backroad route. The lowest of the 2 is listed on the sign as 8'6" which made me conclude that the backroad route wasn't viable but then everytime I go down that road I look at it and I think it's GOTTA be over 10' in the middle of the road. The kicker was the day I came to that overpass behind a full size school bus which went right through it with room to spare. It was obvious the driver was being careful to stay in the middle of the road but there was no issue getting the bus through it.

This incident confirmed my suspicion that height limits on overpasses must be to the lowest point 'considered' to be overhead to vehicles passing under it. In the case of both the overpasses I'm considering, they're concrete arch overpasses and the lowest point on each is just where the side walls start curving into the overhead arch.

Maybe I'll have to run that route in a car and stop at each overpass and measure the height of each to the start of the arch and see if it matches the listed height.

I know there are folks here that drive school buses (musigenesis??) can any of you comment, or maybe folks that drive large trucks on a regular basis.

[musigenesis]

I do drive a school bus now as a job, but I had it drilled into me during training to never go under an overpass where my bus height was at or over the posted height limit - and even with that they make sure we inflate the height of our own buses by about five inches. I think it's actually illegal to do so, but it's probably not really enforced in any way since peeling off the top of your vehicle like a sardine can is punishment enough.

I personally wouldn't go anywhere near a listed 8'6" underpass even though I think you're right about that height being measured way over at the edge of the arch. Or if I did I would stop in front of the arch and get out and check to make sure I would fit, which would probably piss off the cars behind me.

[Oldyeller]

Originally Posted by musigenesis

I do drive a school bus now as a job, but I had it drilled into me during training to never go under an overpass where my bus height was at or over the posted height limit - and even with that they make sure we inflate the height of our own buses by about five inches. I think it's actually illegal to do so, but it's probably not really enforced in any way since peeling off the top of your vehicle like a sardine can is punishment enough.

I personally wouldn't go anywhere near a listed 8'6" underpass even though I think you're right about that height being measured way over at the edge of the arch. Or if I did I would stop in front of the arch and get out and check to make sure I would fit, which would probably piss off the cars behind me.

I probably wouldn't have done this thread if I hadn't watched a bus that looked as high as mine go through an underpass listed as 8'6" with room to spare.

[ewo1]

Hey Oldyeller, you forgot to give us the most important piece of information….

How tall is YOUR bus?

This is something you should know before even thinking about going under ANY canopy or bridge.

As a dumb teenager I learned the hard way and never forgot the lesson. I drove an f350 uhaul box truck, the ones with the attic above the cab, under and office building.

It looked like it would fit until it didn’t. Busted my lip of the steering wheel, destroyed a truck and caused lots of damage to the building.

Lesson learned, know your truck height BEFORE you even consider driving it!
And yes, as a former tractor trailer driver, I have squeezed under many low clearance locations, 1) know YOUR height, 2) get and and look - double check as you approach,.

You did real good though by checking, asking for advice!

Stay safe and keep your teeth your teeth from the steering wheel!

[Oldyeller]

Originally Posted by ewo1

Hey Oldyeller, you forgot to give us the most important piece of information….

How tall is YOUR bus?

This is something you should know before even thinking about going under ANY canopy or bridge.

As a dumb teenager I learned the hard way and never forgot the lesson. I drove an f350 uhaul box truck, the ones with the attic above the cab, under and office building.

It looked like it would fit until it didn’t. Busted my lip of the steering wheel, destroyed a truck and caused lots of damage to the building.

Lesson learned, know your truck height BEFORE you even consider driving it!
And yes, as a former tractor trailer driver, I have squeezed under many low clearance locations, 1) know YOUR height, 2) get and and look - double check as you approach,.

You did real good though by checking, asking for advice!

Stay safe and keep your teeth your teeth from the steering wheel!

I've measured it twice and the best I can say at this point is it appears to be between 9 and 10'. Why can't I be more specific? I've never had the chance to measure the bus on a level, hard surface. Since I took possession of the bus it's been on a gravel pad and that none too level. This week I'm going to try to drive it - for the first time. I haven't decided if I'll drive it locally on the back roads, hopefully out of the sight of the pole-ice, or if I'll bring it to my house and maybe get a week or two of work on the floor before it gets really cold - depends on how bold this old man feels. I only have $250 in road side assistance on the bus so a break down on the interstate would be bad.

Back to the question of overpasses, in my mind this is one of the more critical issues. I don't intend to stay on interstates exclusively and once you hit the secondary roads the possibility of encountering a low underpass is pretty high (see what I did there, LOW, HIGH?? ) yet I don't see much discussion about it here. Does that mean it's a non-issue and I'm a worry-wart or that people that have been confronted with an underpass they couldn't 'underpass' just don't want to talk about it? Oh wait, can't be a non-issue because I started this thread with the statement that on my back road route to get the bus to my house there are 2 underpasses listed at UNDER 9'.

[Mountain Gnome]

I lost my A/C rooftop unit's plastic cover going under an overpass in Indianapolis on a "sideroad" when the construction traffic was bad. I hadn't been driving it much yet at that point, and only noticed the low-overhead at the last moment - too late - all I could do is instinctively duck my head - like that would help. The high-pressure line and the evaporator sat about 1" below the top of the cover. Close call.


Yea, those old roads are an issue.

[Ronnie]

I know my height and I am not about to try an overpass less then my height or even close to it without a spotter. Also if getting close to an overpass in question I look for a spot to pull over or turn around before being committed to it. I have hauled plenty of oversize loads, so am well aware of heights, and other size limitations. Deflating air bags to get under a bridge has been done... Now my bus does not have air bags so no wiggle room there.


Generally speaking you have to be really way off the main roads to find low clearance, I have only had to turn around once.

[TJones]

You dont want to do this.

https://youtu.be/USu8vT_tfdw

Ted

[Sehnsucht]

Not consistent but as a general rule:

If the clearance sign is white background, that's regulatory. Most likely they've measured the lowest point of the overpass and compensating for the road grade you can trust that.

If the clearance sign is yellow background, that's advisory. The clearance has been estimated or could vary depending on how you approach it. For instance, if the overpass is arched, you may be able to make it through if you're in the middle of the arch (straddling lanes on a two-lane) but not if you maintain your own lane. Often times also if the lane is regulation but the shoulder is less, there might be a specific clearance sign with an arrow indicating where in the arch it is lower than standard clearance.

For semi trucks, the national standard has been 13ft 6inches since the early 80s. The STAA designated truck appropriate routes and adequate signage along those routes for anything that's below the standard. In the northeast specifically and in older cities in general, it takes a sharp eye and diligence to avoid getting on the 'wrong' route then encountering an impassible low clearance. And if you end up there, plan on paying multiple fines.

Based on the OP's assessment, I would not attempt any route where there's a known low clearance of 8ft 6inches. I wouldn't trust any full size bus to safely clear that. The problem is often not in the entrance but in the exit. An empty bus is probably taller in the back so it may not hit going in but could scrape on the way out. I watched a semi in Indianapolis who assumed because he fit going in he was safe but the 12'6" was on the exit side where the road grade climbs and the tractor starts up the grade before the trailer is out of the tunnel. It's entertaining to watch the middle of the roof just fold in on itself. Don't be that driver.

[Oldyeller]

Originally Posted by Sehnsucht

Not consistent but as a general rule:

If the clearance sign is white background, that's regulatory. Most likely they've measured the lowest point of the overpass and compensating for the road grade you can trust that.

If the clearance sign is yellow background, that's advisory. The clearance has been estimated or could vary depending on how you approach it. For instance, if the overpass is arched, you may be able to make it through if you're in the middle of the arch (straddling lanes on a two-lane) but not if you maintain your own lane. Often times also if the lane is regulation but the shoulder is less, there might be a specific clearance sign with an arrow indicating where in the arch it is lower than standard clearance.

For semi trucks, the national standard has been 13ft 6inches since the early 80s. The STAA designated truck appropriate routes and adequate signage along those routes for anything that's below the standard. In the northeast specifically and in older cities in general, it takes a sharp eye and diligence to avoid getting on the 'wrong' route then encountering an impassible low clearance. And if you end up there, plan on paying multiple fines.

Based on the OP's assessment, I would not attempt any route where there's a known low clearance of 8ft 6inches. I wouldn't trust any full size bus to safely clear that. The problem is often not in the entrance but in the exit. An empty bus is probably taller in the back so it may not hit going in but could scrape on the way out. I watched a semi in Indianapolis who assumed because he fit going in he was safe but the 12'6" was on the exit side where the road grade climbs and the tractor starts up the grade before the trailer is out of the tunnel. It's entertaining to watch the middle of the roof just fold in on itself. Don't be that driver.

Yesterday I went down this road so I stopped and broke put my tape measure. The center of the arch was somewhere over 15', I really couldn't see the numbers that far away. The measurement at the blue line on the left (low) side of the underpass was 114" and 117" to that deepest gouge.

Obviously my bus would make it through this overpass easily if I kept away from those side walls. Problem is the bend is blind exiting the tunnel from the other direction. The way people drive you could easily end up with a new bumper ornament if you didn't have someone watching for approaching traffic.

The background of the sign is yellow which goes along with what Sehnsucht said, the height limit is not definitive.

I got some good information out of this thread. Thanks Sehnsucht for sharing your knowledge about this.

[musigenesis]

I like how that overpass shows where people tend to hit it.

[Salty Walty]

The interstate can seem intimidating but once you get in the right lane you’re just cruising. Do it at night and have someone follow you to help with lane changes if you’re uncomfortable. As a fellow NJ resident, I get your stress, but backroads have their own headaches with turns and what have yous.

[BFlinn181]

A priority, if driving in areas of low clearances (and bridge weight limits) would be to measure the dimensions and weight of your vehicle. A flat parking lot, a tape measure, and a ladder are your tools. Climb the ladder at the rear center of the bus and eyeball what is higher than the roof arch at the rear. If in doubt, climb up and take actual measurements. (On most buses, the rear overhang is the highest point.)

Take the bus to a CAT scale at a local truck stop to get its weight.

Use Google to search websites that list bridge clearances and weight limitations. Many states, RV groups, etc. have lists of low bridges, weight limits.

[Oldyeller]

Originally Posted by Salty Walty

The interstate can seem intimidating but once you get in the right lane you’re just cruising. Do it at night and have someone follow you to help with lane changes if you’re uncomfortable. As a fellow NJ resident, I get your stress, but backroads have their own headaches with turns and what have yous.

The interstate isn't intimidating from any perspective than that there are NJ state police on it and my bus is far from finished - it doesn't have a rear bumper for instance. It would be easier to take the interstate from a driving perspective. Also if something goes wrong I'd rather NOT be on the New Jersey interstate.

[Artor]

I haven't done it yet, but I've thought about mounting some green lasers to the highest points of my bus, and a button on my dash. If I can see a spot on that bridge/tree/overpass, then I know I can't fit through there. I've also considered getting a camera drone to go with my bus, so I can scout ahead through unfamiliar parks.

[Oldyeller]

Originally Posted by BFlinn181

A priority, if driving in areas of low clearances (and bridge weight limits) would be to measure the dimensions and weight of your vehicle. A flat parking lot, a tape measure, and a ladder are your tools. Climb the ladder at the rear center of the bus and eyeball what is higher than the roof arch at the rear. If in doubt, climb up and take actual measurements. (On most buses, the rear overhang is the highest point.)

Take the bus to a CAT scale at a local truck stop to get its weight.

Use Google to search websites that list bridge clearances and weight limitations. Many states, RV groups, etc. have lists of low bridges, weight limits.

I think I've decided my first drive will be an out and back from my friends farm of about 15 to 25 miles without a shutdown. There's a tiny truck stop that I'll use as the turn around point. That way I can get the bus fully heated up and a nice little drive for the first time in over a year on a not too risky route. If all goes well and it restarts the next time great then I can see if it still makes sense to bring it home for a week or so for some floor work.

[Oscar1]

Come on man! You're worried about the interstate? If this cowboy can do it anybody can

[rossvtaylor]

We have a railroad underpass inside the limits of the City of Flagstaff...and it's accurately marked 13' 6". Hayward, our materials handler "crane truck" fits under that fine...with a few inches to spare... so long as the crane operator's seat back is folded down. Guess why I have a new seat up there? With a shorter seat back, in case I forget to fold the seat down again?

[lawdog71]

Purchase a copy of the Rand McNally Motor Carrier Road Atlas, they list low overpass clearances.


I'm a trucker and we use that resource all the time.


~s

[Oldyeller]

Originally Posted by Oscar1

Come on man! You're worried about the interstate? If this cowboy can do it anybody can
Attachment 62170

LOL, for all we know that guy got a ticket during his little jaunt. I can pretty much assure you that wouldn't work here in the authoritarian communist state of NJ.