Lowest clearances
Michael Moroney
overpass clearance in the US on any:
1) Interstate highway:
a) mainline only
b) including ramps
2) US highway
3) State highway, broken down into primary and secondary/reference routes
and parkways, as appropiate
4) Any other public (city/town/county) route
I mention parkways in state routes, although most states don't have them,
because NYS has several (off limits to trucks) with rather low clearances.
Count such things as the GSP in NJ or ex-MDT parkways in Mass. here.
richard
> Excluding temporary/construction-related work, what is the lowest posted
> overpass clearance in the US on any:
>
> 1) Interstate highway:
> a) mainline only
> b) including ramps
13'6" by federal law.
> 2) US highway
> 3) State highway, broken down into primary and secondary/reference routes
> and parkways, as appropiate
13'6" if a designated truck route, by federal law.
> 4) Any other public (city/town/county) route
>
> I mention parkways in state routes, although most states don't have them,
> because NYS has several (off limits to trucks) with rather low clearances.
> Count such things as the GSP in NJ or ex-MDT parkways in Mass. here.
The lowest I've seen is one in NY that was posted as 8'?". Subtracting 12"
would put the true clearance at 7'?".
NY always posts 12" lower than true because that is the maximum offset
permitted by federal law (MUTCD).
Kenny McCormack
richard <mem...@newsguy.com> wrote:
...
>The lowest I've seen is one in NY that was posted as 8'?". Subtracting 12"
>would put the true clearance at 7'?".
>NY always posts 12" lower than true because that is the maximum offset
>permitted by federal law (MUTCD).
I'm not sure what the ?s above represent, so I'll assume you mean 8' 6"
(i.e., 8.5 ft.) But then wouldn't that make "true" be 9.5 ft?
Assuming that by "lower", you mean "Lower than true".
Like where they routinely post "14 ft. 6 in." when it is really 15 feet.
--
Faced with the choice between changing one's mind and proving that there is
no need to do so, almost everyone gets busy on the proof.
- John Kenneth Galbraith -
richard
> In article <ou4bc2r9...@evanplatt.sux>,
> richard <mem...@newsguy.com> wrote:
> ...
>>The lowest I've seen is one in NY that was posted as 8'?". Subtracting 12"
>>would put the true clearance at 7'?".
>>NY always posts 12" lower than true because that is the maximum offset
>>permitted by federal law (MUTCD).
>
> I'm not sure what the ?s above represent, so I'll assume you mean 8' 6"
> (i.e., 8.5 ft.) But then wouldn't that make "true" be 9.5 ft?
>
> Assuming that by "lower", you mean "Lower than true".
>
> Like where they routinely post "14 ft. 6 in." when it is really 15 feet.
? indicates I'm not sure if there was more posted or not. Just didn't know
how to say that.
By lower, I mean if the actual height is 13'6" then the sign will show
12'6". Which conforms to the MUTCD.
Andrew M. Saucci, Jr.
on Long Island is marked something like 6' 11". Almost all parkway entrances
in Nassau and Suffolk counties are now marked with a standard clearance
plate reading "MAXIMUM VEHICLE HEIGHT 7' 10," for what that's worth.
"Michael Moroney" <mor...@world.std.spaamtrap.com> wrote in message
news:ion426$or7$1...@pcls6.std.com...
Paul S Wolf
That is true in New York, but is contrary to the federal MUTCD. New
York's Supplement does set the legal limit (and the clearance they post)
at 1' less than the actual clearance, if it's less than 14' but that's
NOT what the MUTCD says.
Here's the relevant quotes from the NYSDOT Supplement:
> Section 2B.108 Regulatory Clearance Signs (NYR5-6, NYR5-7)
> Standard:
> 01 Regulatory Clearance (NYR5-6 and NYR5-7) signs (see Sign Drawing
> SD-R7) shall be used to indicate legal overhead clearances at bridges
> and elevated structures when measured overhead clearance is less than 14
> feet. Such legal overhead clearance shall be one foot less than the
> measured clearance (the vertical distance between the traveled portion
> of the roadway and the overhead structure).
and
> Section 2C.27 Low Clearance Signs (W12-2 and W12-2a)
> 00H The clearance displayed on the Low Clearance sign shall be the
> same as that on the Regulatory Clearance sign (or signs) to which it
> pertains.
However, here is the wording for the first 2 paragraphs of the MUTCD
section on these signs:
> Section 2C.27 Low Clearance Signs (W12-2 and W12-2a)
> Standard:
> 01 The Low Clearance (W12-2) sign (see Figure 2C-5) shall
> be used to warn road users of clearances less than 12 inches above
> the statutory maximum vehicle height.
>
> Guidance:
> 02 The actual clearance should be displayed on the Low
> Clearance sign to the nearest 1 inch not exceeding the actual
> clearance. However, in areas that experience changes in temperature
> causing frost action, a reduction, not exceeding 3 inches, should be
> used for this condition.
So, everywhere else in the USA (AFAIK), what the MUTCD says is post the
ACTUAL clearance, if that clearance is less than 12" more than the legal
height limit for vehicles.
So if the maximum height of a truck is 13'6", then any clearance less
than 14'6" should be posted, but the REAL clearance should be on the
sign. You don't post 12'6" if the actual clearance is 13'6".
The exception (the last sentence in paragraph 2) says, in areas where
frost heaving can reduce the normal clearance, the state can and should
post a clearance of 13'3" to 13'5" if the normal clearance is 13'6".
Why NY law requires the state to post incorrect clearances is beyond me.
I'm sure drivers know they can probably get away with going under low
clearances when they exceed the legal (posted) limit if they're only
slightly over height. But that also can lead drivers from NY to be more
likely to have problems anywhere else in the USA if they assume the real
clearance is 12" more than what's posted.
--
Paul S. Wolf, PE, FITE mailto:paul....@alum.wpi.edu
Fellow, Institute of Transportation Engineers
cpzilliacus
wrote:
> Excluding temporary/construction-related work, what is the lowest posted
> overpass clearance in the US on any:
>
> 1) Interstate highway:
> a) mainline only
I-395 northbound at the Third Street Tunnel entrance portal in the
District of Columbia is posted as 13' 0" (but it's higher than that, I
believe).