Overhead Clearence

[Land_Yachters]

So just driving our Tiffin 33 around for first time. It shows 13' height, (which I have not yet verified) but was wondering about the accuracy of clearance signs along the road. If the sign says 13'0", can I trust that?
Didn't see this question posed elsewhere, so thought I would ask.
Thanks
Griff

[Thermoguy]

Maybe I'm not correct here as I just don't think that much about height, I've never measured my 5th wheel, I think it is under 13'. But, what I do know is I am not as high as a semi. So, if large trucks are traveling the road, and they clear the bridge, then I have nothing to worry about or even think about. As for roads that are not main roads of travel, I have yet to come across a low bridge - so far. We have a trip to Glacier scheduled for this summer, I already know they don't allow large trailers into the park and have a low clearance at the entrance, so we will not be going in with our trailer. However, no problem at Yellowstone.

It's good to know your height, but I wouldn't slow down on a freeway unless there lots of signs detouring large rigs due to construction or something. I guess you could be concerned at some gas stations, but I haven't seen a low roof in a gas station in years, or at least one I would be comfortable filling up with a trailer attached.

[ktmrfs]

Another bit of info. Often the clearance listed is the side clearance of the radius not the overhead clearance in the traffic lane. So, for most vehicles the clearance is more than adequate.

There are places I've been that show a 12ft or so clearance where the normal traffic lane is 14ft. Confuses the GPS to no end. This seems to occur on older tunnels not on overhead bridges. Oversized vehicles could be in trouble but not regular vehicles if you stay in the traffic lane.

[navegator]

I measured the unit emty with the air bags pumped to max and then fully loaded, then wen't to Home Despot and puchased a colapsible painter pole and marked both measures, the pole came in handy on one park entrance in Mexico, we made it trough with 4" to spare.

navegator

[pigman1]

Well and good. I worked the survey parties that went into the field to verify that the job was completed according to the contract engineering plans and drawings. I also worked in the engineering office where the necessary work orders were drawn up and forwarded to the other sections for actions. What they're doing now, I don't know, but I watched how it worked when I worked there.

As Dirty Harry said "Are ya' feelin' lucky, P____?" My suggestion. Know your height by measuring it. If you have any question, go another way or hang on the ladder with a phone and look close while someone creeps under the bridge.

[valhalla360]

I work in the field and you are getting a lot of misinformation.

No one is building overpasses without detailed plans and surveyors on site. And they do field verify it was built to plan. A high load hit is a huge hassle.

Even with resurfacing projects, they verify the clearance.

Keep in mind, they build in some fudge factors. They typically list a height that is a few inches lower than reality. Also, the listed height is at the shortest point. Road surfaces crowned meaning there is a high point so water runs to the sides. If you aren't at the crown point, there is more clearance.

[pigman1]

Dutch_12078 wrote:
I've seen state highway overpass signs in NY being updated while the contractor was still compacting the new blacktop.

Yeah, that too. It all depends on how the contract was written.

[Dutch_12078]

I've seen state highway overpass signs in NY being updated while the contractor was still compacting the new blacktop.

[pigman1]

Just to tell you how that clearance sign came to be. Let's assume the road was repaved. Someone will make a WAG (wild a$$ guess) post a temporary sign, you hope, and call the road department. They will send out a survey crew who will actually measure what the clearances are and report it back to the office. Short as a couple of days to a week or longer. The office calls the sign shop (or sends them a work order) and the necessary signs are made (assuming materials available). Once they are made, the signs go back to the highway office where a work crew is scheduled to put the signs in the correct location re the bridge. Maybe another survey crew is sent out, or not to locate the true sign, and maybe the signs are finally put up for all to see. Time? A couple of weeks for the Superman of the road departments, to 2-3 months which would think is about average. BTW, I worked in the department that generally oversaw these actions in the city of Newark, NJ, a long time ago, but I doubt things like this change.

[wa8yxm]

First the good news. Odds are your rig is no longer 13' tall. that is the "Dry" weight empty before you stock up for the trip.. It gets shorter. BUT.. How much???

Second.. if I was approaching a sign that says 13' With that rig... Well.. Very very very cautiously (Been there done that but at 12'6" with my rig.. I cleared)

I wish they would do more "If you hit this you WILL hit that" signs.

[DrewE]

You'll get a variety of opinions.

From what I understand, very rarely if ever are clearances less than the listed amount; generally the actual clearance is slightly (or sometimes not so slightly) more so as to account for the possibilities of repaving, frost heaves, settling of the foundations of whatever is overhead, vehicles bouncing as they travel, etc. That said, it is not a bad idea to be cautious about these things. At the very least do measure your actual clearance requirements for yourself, and maybe consider putting it on a card or sticker on the dashboard for reference. (It can be useful to have your actual overall length and width ready at hand, too; if you have rear view mirrors that can be folded in, the width both with them folded and with them deployed is occasionally handy to know.)

[Desert_Captain]

Allworth, good info especially #2. In rural areas roads get repaved over and over and they can be significantly taller than that height sign indicates, which was usually posted back when God's dog was a puppy. Like you, I add 6" to my actual height, yes I measured twice and then once again until I got the same number three times...

Some places that have tunnels can pose a whole new set of problems, the Blue Ridge Parkway comes to mind. Some of those tunnels are ridiculously low as you get near the right side of the lanes. I see posts just telling folks no problem just stay in the center {over the double yellow} but as a guy who rides motorcycles I take serious offense at that lame advice.

Bottom line, not every RV can safely transit every road. I just wish more folks would realize that and stick to roads that their rigs and skill levels match. Rant off... for now.

:B

[Allworth]

With some warnings, they are fairly accurate. Federal Highway Admin design standards require that they be within 2 inches at time of construction.

However....

1. States have uniformly adopted FHWA standards. Cities and Counties are on their own. Nobody deliberately miss-marks a clearance, but some may not be marked at all.

2. Maintenance agencies tend to leave old signs in place when they repave (except on Interstates) and paving can raise the road surface as much as 1.5", reducing clearance.

3. 13'- 6" is minimum for federal and state roads without advanced warning signs. Minimum is measured at the closest point between the road surface and the bottom of the overhead structure; usually at the right edge line of the right lane.

4. Confirm your actual highest point. (RV manufacturers frequently forget air conditioners or sat dishes) Measure with the unit loaded for travel and the air suspension (if equipped) pumped up. My trailer is 12' - 9" over the front AC. I approach anything less than 13' - 3" (six inches clear) with extreme caution. My height in English and Metric units us written in large letters on a card taped to the driver's sun visor.

A