THEY'RE OUT THERE— An Appraisal of Illinois Enforcement of Overweight and Oversize Vehicles By JOHN W. McCREE Illinois Department of Transportation

The citizens of this State should be proud of the fine transportation services which are readily available to them throughout the State. In recent years Illinois, and other states and local agencies as well, have begun to place greater emphasis on preserving and upgrading existing highways rather than constructing new highway facilities. Weight enforcement measures can also protect pavements from rapid deterioration which results from overweight vehicles. Illinois recognizes the importance of an effective truck weight enforcement program.

Illinois Department of Transportation records show that truck traffic on State highways is continually increasing. That general increase, statewide, is 4.5 percent annually. As can be expected, a large part of truck traffic is interstate travel. Therefore, most of it is concentrated along rural interstates and freeways. Examining rural interstate traffic, IDOT finds on average that it is 75% automobiles, 3% single-unit trucks and 22% multi-unit (semi's) trucks, while the rural freeways have 81% automobiles, 4% single-units and 15% multi-units. On non-freeway highway facilities, about 3% of the traffic is multi-units.

While the amount of truck traffic utilizing Illinois highways is quite substantial, this increased trucking activity is not unique. Other states are witnessing similar conditions.

Recognizing that this growth trend is not a fluke and that it will likely continue and perhaps trend upward as the operating railroad mileage continues to decline, IDOT's concerns are concentrated on safety of the truckers and other highway users and the structural integrity of bridges and pavements.

Prior to 1983, the maximum allowable gross weight for a combination vehicle (semi) was 73,280 pounds, with no axle exceeding 18,000 pounds. However, in 1983 in response to a congressional mandate, these limits were increased along the designated state highway truck route system to 80,000 pounds gross weight with 20,000 pounds allowed on any single axle. The designated system in Illinois includes over 11,000 miles of State highways.

These increased statutory weight limits are of tremendous concern to our engineers engaged in the design and maintenance of bridges and pavement. For example, when comparing an 80,000 pound truck to an automobile, research indicates that the truck will do approximately 10,000 times more damage to the pavement than the car. Also, increasing the single axle limit from 18,000 pounds to 20,000 pounds results in 1.6 times more damage. Lastly, research indicates that an increase from 73,280 pounds to 80,000 pounds gross weight will reduce service life of the interstate system by 17%.

Because of the inherent damage done by heavy trucks exceeding the allowable statutory limits, Illinois is aggressive in enforcing the size and weight laws. Through this enforcement program, it is hoped that the number of overweight vehicles will decrease, thereby prolonging the life of pavements and bridges. For example, the Illinois State Police enforce the weight limits at 32 fixed weigh stations located throughout the State. Twenty stations are on the Interstate system and 12 along other state primary highways.

September 1988 / Illinois Municipal Review / Page 11

Last year more than 5.5 million trucks were weighed, with 1.4% in violation of statutory weight limits. This low violation rate unquestionably attests to the ease for a truck to bypass a fixed scale operation.

These fixed scales are operated by the Department of State Police, Commercial Vehicle Enforcement Bureau. The Department of Agriculture, Division of Weights and Measures, provides certification of the scales on a periodic basis. IDOT's Bureau of Maintenance is responsible for the maintenance and repair of weighing facilities. Equipment is maintained by the Electronic Scale Technician, working state-wide, or scale service companies, dependent upon the extent of repairs. Routine maintenance of the facilities, such as mowing, snow plowing and pavement repairs is accomplished by the respective IDOT district maintenance organizations.

Because some areas of the State do not have fixed scales readily available and also because of the ease for truckers to bypass these fixed scales, the Illinois State Police also utilize 12 crews with semi-portable scales to weigh trucks. Last year these crews randomly weighed 85,000 trucks, finding 8.2% of the trucks in violation of the statutory weight limits. Although the volume of trucks weighed with semi-portable scales is much less than our fixed scales, the overall impact upon overweight trucks is much greater. Through this program, the percentage of violators have continually decreased each year from a high of 18.6% in 1982 to last year's 8.2%.

Generally the semi-portable scales are set up off the travel lane on a paved shoulder or other specially constructed turnout. The typical semi-portable set-up includes weigh platforms capable of simultaneously weighing 3 axles in both wheel paths. The scales can weigh each set of duals separately and the gross weight on the combined axles. A digital reading and printed weights are provided.

Each State Police District has officers responsible for enforcement of 2nd Division Vehicles Laws, including hazardous material movements, motor carrier safety and the size and weight for the District. The semi-portable scale operation typically requires three State Police Officers to direct the weighing operation and issue citations and two IDOT, Bureau of Traffic, employees to handle set-up and operation of the scales and signing. It takes around 20 minutes to set up scales and signs. Normally weighing concludes after 3 to 4 hours. The temporary installation becomes ineffective after that time. The "word" passes quickly among truckers. One of the largest overloads of record with the semi-portable scales is 160,000 pounds, which incidentally resulted in a fine of $21,000.

Now, for the conundrum. When the word passes, "Smokey has the scales out", where do all the overweight rigs go? It's highly likely that they detour on to the local street and highway system where it's very unlikely that local law enforcement agencies are in the weighing business. Perhaps this is still another reason for considering seasonal posting or year-round posting of some highway facilities. How about the bridges on the local systems? Are they rated and posted with the appropriate restrictions? Just thought we'd ask. •

Page 12 / Illinois Municipal Review / September 1988