Low weight bridges

sneakygroundbuzzard wrote:

johnhicks wrote:
I think bridges are limited per axle. Better check with DOT though.

most are gross weight,the sign will show pics of different types of vehicle and the weight limit for the type (i.e. pic of a straight truck,combination vehicle,or truck pulling doubles and triples)

It is very important to understand the local posting styles. Different states/jurisdictions vary on how they post weight limits.

MN posts their highways in tons per axle. I've seen bridges both ways. There area also some bridges that are limited to one vehicle at a time or certain separation distances.

Its a good thing the government keeps things simple.

JW of Opechee Shores wrote:
Having gone to college for civil engineering I can tell you that bridges are designed with a safety factor depending on span. Design will consider how much weight could be on a span should traffic come to a stop in both directions on the span with vehicles at max load. This would be the max dead load and if traffic is m0ving then that is a live load which has less impact. A 5 ton bridge limit should support a minimum of 10 ton plus safety factor.

Having a similar engineering degree and after designing bridges for 15 years I can say that you are correct if you are talking about H-20 loading for major bridges. Short span narrow bridges (which I think the OP is talking about here) that are rated at 5 tons (max.) are not generally covered under H-20 loading where a single axle truck load would be as much as 18,000 lbs. per axle and as much as 80,000 lbs. per vehicle. (well over the 5 ton limit) Most likely the load limit sign is referring to individual vehicles. (total weight) I'm sure there is a safety factor but speaking from experience on old county bridges, they aren't regularly inspected, especially if they are in low traffic areas on or adjacent to private property. That said, it's the OP's rig. Think about where it will be if the bridge doesn't hold. Also, think about anyone else who may rely on using that bridge and how it might affect them if it becomes impassable.

Chum lee

memtb wrote:

johnhicks wrote:
I think bridges are limited per axle. Better check with DOT though.

What John said!

Bridges can be limited by axle or gross or both.
Fines for violating bridge weight limits can be steep. For IL here's the fine schedule which does not include court costs:
625 ILCS 5/15-113
(a) Whenever any vehicle is operated in violation of the provisions of Section 15-111 or subsection (d) of Section 3-401, the owner or driver of such vehicle shall be deemed guilty of such violation and either the owner or the driver of such vehicle may be prosecuted for such violation. Any person charged with a violation of any of these provisions who pleads not guilty shall be present in court for the trial on the charge. Any person, firm or corporation convicted of any violation of Section 15-111 including, but not limited to, a maximum axle or gross limit specified on a regulatory sign posted in accordance with paragraph (e) or (f) of Section 15-111, shall be fined according to the following schedule:
Up to and including 2000 pounds overweight, the fine is $100
From 2001 through 2500 pounds overweight, the fine is $270
From 2501 through 3000 pounds overweight, the fine is $330
From 3001 through 3500 pounds overweight, the fine is $520
From 3501 through 4000 pounds overweight, the fine is $600
From 4001 through 4500 pounds overweight, the fine is $850
From 4501 through 5000 pounds overweight, the fine is $950
From 5001 or more pounds overweight, the fine shall be computed by assessing $1500 for the first 5000 pounds overweight and $150 for each additional increment of 500 pounds overweight or fraction thereof.

Also, if you violate the weight limit and cross a bridge even one that is already in disrepair and it fails it can get really expensive for you. I handled one where a small rural bridge collapsed under a 2 axle tire service truck. When the truck drove over the bridge the support rails buckled which knocked one end off the support pillars. In addition to the fine the company received a civil penalty by the township for replacement of the bridge which exceeded $250,000 in 1980 dollars.

JW of Opechee Shores wrote:
Having gone to college for civil engineering I can tell you that bridges are designed with a safety factor depending on span. Design will consider how much weight could be on a span should traffic come to a stop in both directions on the span with vehicles at max load. This would be the max dead load and if traffic is m0ving then that is a live load which has less impact. A 5 ton bridge limit should support a minimum of 10 ton plus safety factor.

While I don’t disagree about the design factors, I will say that there are a great many bridges in this country which cannot support their design weight due to age, erosion around the supports or simple lack of maintenance.

Many county road bridges which do not get state funds are in horrible shape. I try to avoid traveling on county roads if possible.

Another reason to research your route and not blindly trust a GPS.

johnhicks wrote:
I think bridges are limited per axle. Better check with DOT though.

What John said!

sneakygroundbuzzard wrote:

MDKMDK wrote:
There are some trucker oriented GPS units that will give you a better chance of avoiding height, width, weight problems between where you are and where you want to go.

i drive semi for a living an have a rand mcnally trucker gps unit and keep it updated weekly

for the most part it will route you around low bridges and restricted weight bridges and roads.

but i have run into few that arent in the gps data base.

not to mention not all of the restricted weight bridges have a sign a mile before you approach them,some are right at the beginning of the bridge and i have seen a few where the sign is in the middle of the bridge.

with either of these two scenarios by time you see the sign its already to late and you better hope theres no popo around because your already going to be on the bridge.

i think that part of the reason some of these bridges arent in the gps data base is because their weight limit has been down graded because the structural integrity of the bridge is no longer up to par and waiting to be repaired(lot of infrastructure issues in this country)

We've crossed a few bridges here and there that have looked like they couldn't support their stated max weight limit. Mostly off the beaten path, so beware of those back roads.

Having gone to college for civil engineering I can tell you that bridges are designed with a safety factor depending on span. Design will consider how much weight could be on a span should traffic come to a stop in both directions on the span with vehicles at max load. This would be the max dead load and if traffic is m0ving then that is a live load which has less impact. A 5 ton bridge limit should support a minimum of 10 ton plus safety factor.

johnhicks wrote:
I think bridges are limited per axle. Better check with DOT though.

most are gross weight,the sign will show pics of different types of vehicle and the weight limit for the type (i.e. pic of a straight truck,combination vehicle,or truck pulling doubles and triples)

MDKMDK wrote:
There are some trucker oriented GPS units that will give you a better chance of avoiding height, width, weight problems between where you are and where you want to go.

i drive semi for a living an have a rand mcnally trucker gps unit and keep it updated weekly

for the most part it will route you around low bridges and restricted weight bridges and roads.

but i have run into few that arent in the gps data base.

not to mention not all of the restricted weight bridges have a sign a mile before you approach them,some are right at the beginning of the bridge and i have seen a few where the sign is in the middle of the bridge.

with either of these two scenarios by time you see the sign its already to late and you better hope theres no popo around because your already going to be on the bridge.

i think that part of the reason some of these bridges arent in the gps data base is because their weight limit has been down graded because the structural integrity of the bridge is no longer up to par and waiting to be repaired(lot of infrastructure issues in this country)

I think bridges are limited per axle. Better check with DOT though.