Heavy Home Schooling

In the education of a truck driver, size and weight information is low priority. But learn this: a sledge, a 50-foot tape, an air gauge and pencil and paper can help a driver keep his weight, width and length legal.

Lance Gates, an old pro now retired, says he learned by doing. “I learned to run the right hours, the right roads, and listen to my radio to avoid coops and DOT checks.”

While this method works at least some of the time, it’s still a better idea to comply with the law rather than try to avoid it. To comply, smart drivers need to upgrade what they know about gross weight, axle weight, and the morass of secondary road restrictions in different states and municipalities. Same goes for size regulations. Rather than learning by unfortunate experiences, the smart driver can avoid a great deal of difficulty by learning more than just what industry programs teach them. Even driving school graduates, more numerous now than in days of yore, get little or no instruction in these areas. Many of them are the rookies who pull onto a weigh station not knowing whether their trucks are loaded correctly. Some have been caught early in their careers and begun to recognize the need to educate themselves. Others have gotten the go light and gone on their blissfully-unaware ways. With some luck, this latter group can run around the countryside oblivious of the laws until they’re finally caught, years or months later.

Smart drivers may also be lucky, – and a smart driver’s good luck is made by his efforts to stay informed- but it is not in the best interest of the super slab’s finest to rely on luck to avoid the long arm of the law. While the basic size and weight regulations have been in effect for many years, the fine print remains uncharted territory for many. South Dakota’s frost laws, Pennsylvania’s width laws on certain secondary highways, North Carolina’s further bridge formula restrictions on the 80,000 pound gross weight regulation, are all examples of details in which devils may reside.

To begin with, not all of the roads that trucks travel are governed by the same set of laws. Federal laws govern three types of roads, the Interstate System and the National Network, which includes designated primary highways.

Look at one example of the complexity of the rules. Leaving the Interstate System, which is governed by federal weight laws, means you are now subject to state laws governing weight. You are, however, still subject to federal width and length laws, which may or may not be the same as state laws, according to Title 49 USC 31111 and 31112. In general, “States shall not impose a length limit of less than 48 feet or the grandfathered length.” In Vermont, for example, 53-footers need a permit to leave the National Network. And in Michigan, “trailers over 50 feet require no more than 40 feet, 6 inches spacing, plus or minus 6 inches, as measured from kingpin to center of rearmost axle,” according to Title 49. In Georgia, 53 footers are permitted only if the kingpin setting is 41 feet.

To further complicate matters, the federal bridge law has a bearing on size and weight limits. As you might expect, the bridge laws are meant to prevent overstressing of highway bridges. Incorrect spacing of axles may reduce the 20,000-pound single axle and the 34,000-pound tandem limits. Adding axles or positioning axles farther apart can increase these limits up to the gross allowable weights, according to Title 23. Pulling a flat with a 10-foot-1-inch Canadian spread increases the gross on the trailer to 40,000 pounds but does not allow any increase in the 80,000-pound limit. Loading 40,000 pounds on your trailer tandems therefore means the weight must be reduced on the drives, the steer, or a combination of both.

There is a complicated-looking formula taken from the Title 23 regulation you can use to check for bridge law compliance. Its looks should not deceive the smart driver. It is a simple matter of using addition, subtraction, division and multiplication, tasks to be performed after checking gross and axle weights for compliance with standard weight requirements. Here’s the formula according to J.J. Keller & Associates’ website, www.kelleronline.com: W=500(LN/N-1+12N+36) Here W equals weight. For example, a five axle unit with its first axle 51 feet from its last axle can carry the maximum 80,000 pounds. Here the bridge law and gross weight coincide, giving you a base line by which to judge your weight and spacing. Axles one through three, at 20 foot spacing, can carry a maximum of 51,000 pounds, well beyond the sum of the steer maximum of 12,000 and the drive max of 34,000. Axles two through five at 35-foot spacing can carry 65,500 pounds. If any of the above axle combinations exceed the mentioned weights you are in violation of the bridge law even if your axle weights are legal and you are under gross.

This gets complicated when your axle spacings differ from this example. That’s when you need the formula. Once you have weighed and know your three axle spacings, it is not difficult to plug the numbers into the formula. Solving the equation and finding out your weight exceeds the numbers mentioned above means you need to slide your fifth wheel, or more likely, your trailer axles.

To solve the formula, multiply your real axle length, or L, by N, the number of axles. Divide that by number of axles minus one. In this case that amount is three. Then multiply the number of axles by 12 and add 36. Multiply this number by 500, which is W, to get your true weight on those axles. Compare this number with the maximum allowed as shown above. This should keep you out of trouble.

There is one exception to this rule, but it is one that works in your favor. A minimum of 36 feet between axles two and five allows you to put 34,000 pounds on the drives and 34,000 on the trailer for a total of 68,000 pounds. Using the table or the formula would indicate weights of 66,000 to 67,500 for spacings of 36 to 38 feet. Thus the exception allows more payload.

So far, the regulations considered have applied only to the National Network, meaning the interstates and primary highways. While Title 49 USC 31114 tells the states that they must provide reasonable access to trucks getting off the National Network to go to terminals and service facilities, this access is limited to one mile in many states -although the distance varies from one mile to unlimited, according to the access chart in Rand McNally’s Motor Carrier Road Atlas. In Kentucky, the distance is five miles on state-maintained roads and one mile on others. Beyond this distance, a permit is required. And in Massachusetts, 53-footers are not allowed beyond the National Network without a permit.

Be prepared! Signs can both surprise and confuse the ill-prepared trucker.

Smart drivers will take advantage of the information in Rand McNally, which can help far beyond finding where East Podunk is. The safest course of action when going beyond the National Network is to call the appropriate state agency, also listed in Rand McNally, to get an explanation. Reading a sign on a skinny two lane in the Keystone that says, “PROHIBITED: ALL TWINS AND TRAILERS OVER 28.5 FEET 3.5 MILES SOUTH ON PA 65,” means it is probably too late to avoid breaking this ordinance. Nor is it true that only skinny two lanes have such prohibitions. US 15 running north and south through the Keystone has sections where 102 inch wide trucks are permitted and sections where they are not. Enforcement of these regulations may be spotty, but some states, like the Keystone, often set up DOT checks at places where regulations change. Jim Weakland at the Pennsylvania Office of Motor Carriers says that, “the municipality may have asked for a truck ban on that section of road for safety reasons.” Other similar signs on Route 18 between the turnpike entrance and the steel plants of neighboring towns say PROHIBITED: 102 IN. TWINS AND TRAILERS OVER 28.5 FT. According to Weakland this means 96 inch wide trailers of any legal length are permitted. But the confusion caused by some signage means that drivers need to be especially careful.

Darren Roth, Director of Highway Operations for the American Trucking Associations isn’t kidding when he says, “Once off primary highways, various state laws apply.” Indeed, city laws may also apply. Lisa Burns, Permit Liaison for the New York City Department of Transportation says, “New York has a length limit of 55 feet total.” When asked what the legal weight limit was she said only that the driver is required to know the weights of his truck and axles. J.J. Keller’s Vehicle Sizes And Weights Manual lists New York City’s gross vehicle weight at “34,000 pounds plus 1,000 pounds for each foot and major fraction of a foot of the distance from the center of the foremost axle to the center of the rearmost. Total weight should not exceed 73,280 pounds.” Tandem axle weight maximum is 36, 400 pounds and single axle maximum is 22,400.

Burns’ advice applies in any driving environment. Complying with regulations on the typical trip may only mean checking ground pressure and making sure you comply with the bridge law. If you work for a company that uses a variety of differently sized trailers, knowing your overall weight and overall dimensions can help load your wagon correctly and keep you in compliance. While everybody thinks about weight, switching to a 102 wide trailer and going down the same road you’ve traveled carefree with a 96 can get you in hot water. Certainly the same is true if switching from a 48 to a 53 footer. Most 53s have a mark to show where the trailer tandems would be on a 48 and most guys pretty much leave it there unless they’re worried about the bridge law.

But you can’t even think about getting into compliance if your slider is stuck. Besides being armed with information, you can often use a sledge hammer to coax the pins in your slider out of their little holes. Remember, every hole shifts about 400 pounds of weight. A 50-foot tape measure will help with axle spacing. Armed with a good road carriers’ atlas and some hand tools, and possibly a pencil and paper to work out the bridge formula, you can pretty much stay out of trouble. But remember, getting off the Interstate means the weight laws are now under state control and getting off the National
Network requires increased vigilance and planning to avoid width and length fines your company may not want to pay.

According to Thomas Klemik at the Federal Highway Administration, there are no federal height laws.

Joe Storey hauls super heavy for Miller Transfer and Rigging. Storey and other heavy haulers have a simple method of checking weights that does not require an in-the-ground scale. Their method can be useful when you’re unable to weigh before crossing the coops on the big road or when you need to know if your weight is legal off the National Network. This will not work if you change trailers constantly but if you drive for a small outfit and deal with only a few, it may save some grief. Your tire pressure gauge and a small T fitted onto your air suspension system can be used to give you an accurate gross. This requires scaling your truck and reading the pressure at that weight. Knowing air pressure at the weight you have weighed gives a baseline. From there you can find your true weight by simply taking a reading of air pressure and comparing it to the air pressure when you scaled. Remember to use the air gauge on both tractor and trailer, taking readings on level ground. According to Storey, this method is “every bit as good as on board scales and better than suspension pressure gauges in the dash. Dash gauges will only give tractor weight,” he said.

Why the professional driver is not taught these simple procedures defies understanding. While the industry continues to look for quality in its work force, it doesn’t do enough to educate him about this significant issue. In the absence of industry initiative, it is up to the smart driver to educate himself. Fleets and truck driving schools would do well to use J.J. Keller’s excellent resources to upgrade their curricula.


Size and Weight Tips

  1. Don’t assume you know the weight laws. Despite a general consistency on the interstate, laws are much less straightforward once you hit the exit.
  2. The bridge law is not as complicated as you may have been led to believe. The formula is simple once you use it a few times. Don’t let a DOT guy be the first to use the bridge law on your fat wagon.
  3. Remember that switching from a 48-footer to a 53-footer, or vice versa, changes your bridge and axle weights.
  4. Knowing pallet weights and weights of individual pieces of freight, and paying attention when loading, can keep you in compliance. Use the half hour you log as loading time to figure out where the weight you’re loading applies itself to the ground.
  5. If you pull for a big outfit, make use of dispatch when you are unsure about weight and weight laws. It is possible to minimize fines if you know that a bridge law fine will be less than an overweight fine, for example, when you can only avoid one or the other.
  6. Make sure your fifth wheel slides and your trailer slide moves before you get into a spot where they need to work and they don’t.
  7. Fuel weighs 8 pounds per gallon. In a fix you can run close to empty until you cross a scale, then put just enough in to make the next fuel stop on the other side of the next coop. You will lose considerable weight from your drives by doing this if you need to do it.
  8. Don’t believe everything you hear on the radio.
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