Heavier Trucks for our Highways?

[The Davy Crockett]

There is a bill in front of the House to increase allowed truck weights on our highways from 80,000 lbs to 97,000 lbs. (Text of H.R 612 is here.) This, while Congress had already ordered a study, which is underway, on the issue. Needless to say there is widespread opposition to this coming from the railroads, their suppliers their unions and it seems just about everyone else involved in shipping frieght by rail. Here is a copy of a letter they have sent to House members urging them to not co-sponser the bill submitted by Representitives Mike Michaud (D-ME) and Reid Ribble (R-WI) - who is also vice chair of the Highways and Transit Subcommittee on the House Transportation and Infrastructure Committee.

My understanding is that trucks, due to their weight, already cause a disproportianetly large amount of the wear and tear to our highway and bridge infastructure. So lets let them do more damage so they can make the most of their highway taxes! :angry2: :angry2: :angry2:

EDIT: So it occured to me that both sponsers of this bill are from states that border, or are close to, our neighbor to the north. And guess what it allows? 100,000 lbs. - surprise, surprise - according to this article.

Here are a few quotes from the article:

"In my state, the main roads from Canada allow higher weights, so trucks coming from there cannot use the highways and must be diverted to secondary roads. That's a safety issue," says Rep. Michael Michaud (D-ME). "It's also an economic competitiveness issue when the countries we trade with can load their trucks to 100,000 lbs., while we are limited to 80,000 lbs. That's why I'm encouraged by the willingness of Congress to be open about this issue."

Here is the perspective from someone who drove semis for 25 years:

Adding a third axle to the trailer would increase the maximum allowable trailer weight to 51,000 lbs., exceeding the tractor's allowable designed weight of 46,000 lbs. by 5,000 lbs. This would create a dangerous kinetic force that could easily push the tractor out of control when attempting to stop on icy, snowy or wet road surfaces, says Brady."Add to that descending a steep mountain grade in the same conditions, and even an experienced veteran driver will surely be challenged to keep the vehicle under control," he continues.

While adding an extra axle to the trailer spreads out the weight while a commercial vehicle is going down the road, on a parking lot or backing up to a dock, that third axle could cause a tremendous amount of damage as it twists and grinds into the pavement, Brady notes.

 

[Swadian Hardcore]

I don't care about heavier trucks on the road, but I would like the weight to be separated into two trailers. If they can run in Canada, they can run down here. I would really like to see more LCVs here in the US, they're very common in Australia and weight up to 400,000 pounds!

 

[railiner]

I am opposed to increasing the weight (and the size) of trucks that use public highways. Besides the wear and tear on the road surfaces, the bigger and heavier trucks pose a safety hazard for other public road user's. In the event of a collision with an auto, forget about it....

And the longer, heavier trucks pose an even greater challenge when trying to pass on highway with only one lane each way. Not to mention the problem of them trying to negotiate corners on city streets that were designed for vehicles half their size.

And I don't think multiple trailers are the best solution either. Just one trailer is bad enough on a slippery road.

I'm on the side of the railways in this case. Let the trains carry the trailers for the long haul, and let trucks deliver them at their destinations. And no, I have no stock or financial interest in railroads. But as a motorist, I do have to share the highway with trucks.....

 

[afigg]

Increasing the maximum weight for trucks was fought over in the last session of Congress and did not get passed. The odds of the weight increase getting passed this time around are probably longer. With around 72 thousand officially structurally deficient bridges in the US, crumbling roads and highways with a huge repair and replacement backlog, increasing the allowed weight to 97,000 lbs is not exactly going to help.

 

[Swadian Hardcore]

But maybe those bigger trucks will reduce the amount of cars going over the speed limit. When you can't pass a huge, slow truck, you better not overspeed.

 

[gswager]

In Idaho and perhaps some of NW states, the maximum gross is 106,000 lbs. Main factor for determining the maximum vehicle weight in each states is the bridges.

 

[The Davy Crockett]

In Idaho and perhaps some of NW states, the maximum gross is 106,000 lbs. Main factor for determining the maximum vehicle weight in each states is the bridges.

That applies to non-Interstate Highways. From the FHA website:

Commercial Vehicle Weight Standards
National weight standards apply to commercial vehicle operations on the Interstate Highway System, an approximately 40,000-mile system of limited access, divided highways that spans the nation. Off the Interstate Highway System, states may set their own commercial vehicle weight standards.

Federal commercial vehicle maximum standards on the Interstate Highway System are:

Single Axle: 20,000 pounds

Tandem Axle: 34,000 pounds

Gross Vehicle Weight: 80,000 pounds

Bridge Formula Weights

The bridge formula was introduced in 1975 to reduce the risk of damage to highway bridges by requiring more axles, or a longer wheelbase, to compensate for increased vehicle weight. The formula may require a lower gross vehicle weight, depending on the number and spacing of the axles in the combination vehicle.1

 

[PRR 60]

The Pennsylvania Turnpike (an interstate by designation only) allows up to 125,000 pound vehicles without a permit. PA Turnpike bridges were engineered to the same standards as the interstate highways. As long as axle spacing meets standards, a 100,000 pound truck will not detrimentally affect the structural integrity of a bridge designed to normal highway standards. The federal interstate weight limit is partly a political consideration and is not entirely based on engineering issues.

 

[PRR 60]

...My understanding is that trucks, due to their weight, already cause a disproportianetly large amount of the wear and tear to our highway and bridge infastructure. So lets let them do more damage so they can make the most of their highway taxes!

...

That is largely a myth. While trucks do more damage than cars to bridges and pavements, the additional damage is less than the the weight ratio. An 80,000 pound truck does not cause 20 times the damage as a 4000 pound car. In fact, traffic load is only one factor in the usable life of a roadway or bridge and the cost of maintenance. Environmental issues play a larger role. A pavement subjected to zero traffic will not significantly outlast a pavement with normal highway traffic.

Bottom line is that the introduction of 100,000 pound trucks onto the interstate system would not have a measurable impact on the cost of highway maintenance or the life of the pavement and structures.

 

[The Davy Crockett]

I'm not an engineer - if you don't count my dreams of being in the cab - so I'll be the first to admit I'm in over my head, but here are two articles which seem to indicate one truck does as much damage as 9.600 cars: 1)From WHSV, Harrisonburg, VA and 2) From USA Today

Now admittedly I'm citing FOX and USA Today, neither of which are exactly known for their scholarly work, but here is a very methodical study done by Iowa State University, Institute for Transportation, Center for Transportation Research and Education, entitled "A Methodology for Determining Road Damage Due to Railroad Branchline Abandonment" which goes through a series of mind-numbing calculations to reach the conclusion that:

There also are road damage costs of truck wheat movements from study area country elevators to terminal elevators (i.e., intercity movements) (2). The roads used by trucks in the intercity wheat movements are generally of higher quality than those used in the farm-to-country elevator movements. However, the larger trucks moving over greater distances more than offset higher road quality and inflict much more damage. With no abandonment, total road damage cost attributable to trucks would be $1,451,494. Assuming abandonment these costs would increase to $2,182,725, a 50 percent increase. The truck attributable road damage cost that would result from abandonment, is the difference between the above two figures: $731,231. All of this cost would occur on state funded arterial and collector roads.

Total truck attributable road damage cost that would be due to abandonment is $1,004,590 ($273,359 + $731,231), a 48 percent increase from the no abandonment case (2). Of the total damage cost, 27 percent is due to farm-to-country elevator movements and 73 percent to country elevator to terminal market movements. The one million dollar cost is probably conservative since the network model is unable to incorporate rail movements of wheat to local area flour mills. After an abandonment, some of this wheat would also be diverted to commercial trucks.

As I said, I'm in over my head, but this seems to indicate a fair amount of damage from trucks using the roads in place of railcars.

 

[Swadian Hardcore]

The Pennsylvania Turnpike (an interstate by designation only) allows up to 125,000 pound vehicles without a permit. PA Turnpike bridges were engineered to the same standards as the interstate highways. As long as axle spacing meets standards, a 100,000 pound truck will not detrimentally affect the structural integrity of a bridge designed to normal highway standards. The federal interstate weight limit is partly a political consideration and is not entirely based on engineering issues.

That's one of the oldest limited-access highways in the US and so of its bridges are really in disrepair. If the Pennsylvania Turnpike is holding up to those loads, then almost any other road can.