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.ThanksGriff

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

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

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.)

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.

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.

Overhead Clearence | Good Sam Community

Desert_Captain
Explorer III
May 28, 2020
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
Explorer II
May 28, 2020
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

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