Bridge laws are a fact of life for many of today’s dump truck operators.

Federal highways are governed by the federal bridge formula, which uses a mathematical formula to calculate legal axle weights and spacings. This is complicated by the fact that state requirements vary. “Some states have more restrictive laws (aligned with the Federal Bridge Formula). Others have more liberal laws that abide by the Federal Bridge Formula on the interstate highways, and allow greater payloads on fewer axles or less distance between the axles on roads other than interstate highways,” explains Scott Smith, Flow Boy.

Where you are located and which roads you use to haul loads will determine the most productive dump truck/trailer solution. If in doubt, it is always advisable to seek the advice of a local dealer who is familiar with the regional regulations.

When facing the Federal Bridge Formula, dump trailers offer a productive solution to straight trucks. “By giving a greater distance between the axles or groups of axles, the unit (truck and trailer) is allowed to carry a greater legal payload, per the bridge formula,” says Smith.

Maximize Assets

Youngren Excavating, Boone, IA, is an excavating contractor that builds small commercial sites and building pads and performs demolition work. Like any construction firm, Youngren Excavating strives to maximize utilization of its equipment fleet.

Starting out with an excavator, a dozer, a semi tractor and a lowboy, Dave Youngren chose a Circle R Side Dump trailer for his operation instead of a traditional dump truck. “Instead of buying a dump truck, I wanted to utilize the license and the truck I was using to pull the lowboy,” he explains.

The side dump trailer was the best fit for Youngren’s application. “The company that I worked for before used end dump trailers,” he notes. “If you are not exactly level, you will tip them over. You had to basically load them from behind or you would not get the load centered and they would want to tip over.”

The side dump also maximizes versatility. “This does not have a tailgate that debris is going to get hung up on,” explains Youngren. “You can basically haul anything in them. The only downfall would be spreading rock.”

Youngren Excavating continues to grow, adding a second Circle R Side Dump last year. The two semi trucks pulling trailers provide the capacity Youngren needs without excess capital tied up in equipment. “When I am loading dirt with an excavator, the capacity I am getting is basically the same capacity as four dump trucks,” says Youngren.

And that does not take into account the faster cycle times. The side dump cycles faster than a conventional dump truck because it doesn’t have to be backed into position.

Choose The Correct Trailer

Dump trailers come in many forms. End dumps, live bottom dumps, side dumps and bottom dumps are among the most popular. Choosing the correct trailer really depends on what materials you plan to move and how the jobsite is set up.

“The trend in the dump trailer market is people definitely want to get more payload, but they don’t want to give up versatility,” says Dean Badinger, division sales manager, Trail King/Red River. End dumps are among the most versatile trailers on the market, capable of handling a wide array of materials. But to maximize the payload with an end dump under the bridge laws, you need to use longer trailers. This is where stability can become an issue.

“The downside of the end dump is in order to get to 80,000 lbs., you are typically dealing with a 38-- or 39--ft. end dump,” says Badinger. “When you lift that big a trailer up in the air, you have to be in a pretty stable environment. You always have the threat of tipping over.”

The dump site must be kept fairly level. “Hopefully, one side is not softer than the other,” says Badinger. “When you take that dump trailer up in the air, you are transferring a lot of weight to those back axles. If the ground on the driver’s side is softer than on the passenger side, it can start sinking. The next thing you know, you start tipping.