97,000 pound trucks in the future?

[Capt Worley PE]

FORT WORTH, Texas — Drivers could share the highways with much heavier trucks if Congress decides that the efficiencies of larger loads trump concerns about road damage and safety.

The Safe and Efficient Transportation Act would raise the maximum weight for commercial trucks that routinely travel on highways to 97,000 pounds in most states.

The current threshold in most places is 80,000 pounds unless the truck has a permit to be overweight.

Read more here:

http://www.thestate....l#storylink=cpy

I'm thinking this is just what we need, if our goal is to further hasten the ruination of our roads.

 

[Road Guy]

asphalt is only $90/ton so who cares about the roads taxpayers have to fund to maintain right?

 

[goodal]

I thought this was about alot of water trucks!

 

[Dexman PE PMP]

Just going through some of the math:

80k lbs over 5 axles = 16000 lbs/ axle

97k lbs over 6 axles = 16166 lbs/axle

By doing this weight increase, you'll only need ~4 trucks per 400k lbs instead of 5, so the ESAL's are only marginally increased.

I don't know the details on the gas mileage for these rigs (especially overweight ones), but I would think this weight increase would generate a small savings in gas (20% fewer trucks combined with an expected lower gas mileage of heavier trucks). However, if this generates more trucks on the road from an expanded trucking industry, the reduced gas mileage would generate more gas tax $ to help offset the faster deterioration.

I think the bigger savings would come in the labor by generating a 20% reduction in truck drivers (once all the new trucks are fitted with a 6th axle).

Honestly without any more info on the details (gas mileage, costs of new trucks, etc), I don't see where any benefit or savings would come out of this. Seems like it would end up being a push.

 

[Dexman PE PMP]

BTW, what is a pond truck? Is that like a mobile swimming pool?

 

[mudpuppy]

Michigan already allows up to 164,000 lb gross vehicle weight, spread over 11 axles. Our roads are crap, but I think it has more to do with the freeze/thaw cycle and the huge amounts of salt they use on the roads than the weight.

I'd be more worried about idiot drivers and the extra momentum they are carrying in a crash than the impact on the roads.

 

[mudpuppy]

Some light reading on the subject if anyone is interested: http://www.michigan.gov/documents/mdot/MDOT_MI_Truck_Weights_232489_7.pdf

 

[Road Guy]

for States and Counties that do some maintenance it wont be a big issue, but for most that just dont have elected officials that prioritze the funds any weight increase over time will be an issue, especially for bridges.. some of the Cities and Counties in rural parts of our state dont do anything with their bridge inventory..

 

[Dexman PE PMP]

^^^ the other areas that would see the most effect would be the industrial areas of major cities. The surface streets, arterials, and highways through these areas are already torn to $hit.

 

[McEngr]

So much for HL-93 loading... :\

 

[MA_PE]

Dex is right on. Although the gross weight would increase, the loa/axle would likely stay the same. The most profound effects would be on bridges that need to carry the full load on the span. Of course routes would be limited until the bridges are load rated for the additional load.

 

[Capt Worley PE]

Wouldn't the sixth axle be adding 20% more stress cycles to the pavement per truck, or does it not work that way?

 

[Dexman PE PMP]

^^^ only if the number of trucks stays the same. The assumption is that roughly the same amount of goods needs to be shipped, but since the capacity of the trucks increased, the number of trucks needed is decreased, thus keeping the ESALs (equivalent single axle loads) roughly the same.

 

[Capt Worley PE]

Has the number of trucks EVER gone down when the loads were increased?

I remember back in the late sixties and early seventies, they had some truly weird tractor/trailer combinations due to differing state rules. You don't see dromedaries or 48" cabs any more.