Idaho Highways 6, 8 and 9

Thank you for providing feedback during the online public hearing for a 129,000 pound (129k) route application affecting several highways in Latah County. The comment period closed December 21, and now comments will be reviewed by ITD before a decision is reached. A decision could come as early as late January.

 Download application map. 

Bennett Lumber Products is applying to utilize commercial loads up to 129,000 pounds on Idaho Highway 6 (ID-6) from the US-95 junction to Harvard, Idaho Highway 9 (ID-9) from Harvard to Deary and Idaho Highway 8 from Deary to the US-95 junction.

The purpose of the application is to transport lumber now and possibly wood chips in the future. Formerly the applicant was able to use the Washington Idaho & Montana Railway to transport its products, but that service has been discontinued.

The transition to 129k trucking is expected to reduce truck traffic.

 You can read the application by clicking here. 

These highways are predominantly flat or rolling terrain and are coded as “Blue Routes,” where vehicles with 95 foot overall vehicle length and a 5.50-foot off-track are allowed. Loads weighing up to 129,000 pounds would meet these safety requirements. All thirteen bridges are already capable of safely carrying 129k loads.

ID-6 is an asphalt paved rural arterial route rated in good condition. The speed limit varies from 25 mph to 55 mph, with traffic volumes ranging from 1,700 to 4,300 vehicles per day on average. Truck traffic accounts for 4.72 to 12.35 percent of all traffic. This section has no high accident locations, and of all the crashes in the last five years (2015-2019), only one crash involved a tractor-trailer combination.

ID-9 is an asphalt paved rural arterial route rated in good condition. The speed limit varies from 40 mph to 55 mph, with traffic volumes ranging from 1,000 to 1,100 vehicles per day on average. Truck traffic accounts for 7 to 10.82 percent of all traffic. This highway has no high accident locations, and none of the crashes in the last five years (2015-2019) involved a tractor-trailer combination.

ID-8 is an asphalt paved rural arterial route with a short concrete section in Moscow. The highway is in mostly good condition, with poor areas from MP 5.05 to 10.63 and fair areas from MP 3.29 to 5.05 and 10.63 from 14.26. The speed limit varies from 25 mph to 55 mph, with traffic volumes ranging from 1,200 to 15,500 vehicles per day on average. Truck traffic accounts for 2.96 to 8.75 percent of traffic. This section has no high accident locations, and of all the crashes in the last five years (2015-2019), only two crashes involved a tractor-trailer combination.

For specific data on pavement conditions, traffic volumes and crashes, read the engineering evaluation.

ITD engineers have evaluated the conditions of the bridges and roads as well as safety data for highway sections included in this application. The analysis determined the route is appropriate for 129k loads. You can review the full analysis by clicking the button below.

The primary difference between a 129k load and a load that weighs 105,500 pounds is of course the weight; visually, you can usually identify the heavier load by its extra axles or sometimes the addition of a pup trailer.

To the left, you can see the different legal configurations for commercial vehicles. At the bottom are the configurations for 129k loads.

Notice how the 129k configurations require more axles. This spreads out the load over a greater surface area, reducing the impact to the roadway. It also increases the available braking power, ensuring loads meet safety standards for braking.

 Download existing 129k routes.  

Before submitting your comment, please finish reading the FAQs below. Written comments can be emailed to officeofthechiefengineer@itd.idaho.gov or mailed to the attention of Freight Program Manager Scott Luekenga at P.O. Box 7129, Boise, Idaho 83707. Oral testimony can be recorded at (855) 785-2499.

If you have questions you would like to discuss before giving comment, you may call Freight Program Manager Scott Luekenga at (208) 334-8057.

Q: Why does Idaho have a 129k route program?

A: In 2013, at the request of the trucking industry, Idaho Legislature authorized the permitting of trucks weighing up to 129,000 pounds to operate on designated Idaho highways. The permitting of 129k trucks allows for combining shipments, which in turn decreases the number of trips a truck must make, supporting Idaho’s agricultural, forestry, mineral and manufacturing industries. Furthermore, the 129k route program reduces congestion on state routes, provides for a safer highway system and reduces impact of trucking on the environment.

Q: What are the applicable laws governing the 129k program?

A: Below are the applicable laws:

• Idaho Code Title 49, Motor Vehicles, Chapter 10 – Weight, Speed and Tire Regulations
• IDAPA 39.03.03 Rules Governing Special Permits - General Conditions and Requirements
• IDAPA 39.03.06 Rules Governing Special Permits for Extra-Length Excess Weight, Up to 129,000 Pound Vehicle Combinations
• IDAPA 39.03.22, Rules Governing Over Legal Permits for Extra-Length Vehicle Combinations

Q: When did Idaho start allowing 129k trucks?

A: In 2003, as a result of ITD receiving an application to allow trucks weighing up to 129,000 pounds, the Idaho Legislature passed House Bill 395, which created a pilot project to test the effects of increasing the legal truck weights on state highways. The pilot project revealed no adverse impacts to Idaho highways, so in 2016, the 129,000 Pound Program was officially adopted. The interstate system (I-84, I-86, I-15, I-90, I-184) was approved by the federal government on July 1, 2016, to allow 129,000-pound trucks.

Q: What criteria does ITD use to conduct its evaluation of a route in order to ensure the route is suitable for 129k trucking?

A: ITD operates with the mission of safety, mobility and economic opportunity for all motorists on the state highway system. Criteria used to analyze a route includes a safety analysis of vehicle accidents and fatalities, an assessment of pavement and bridge cracking, roughness or ruts and the route's ability to accommodate off-tracking requirements to include route width and curvature. Additional consideration is given to traffic volume.

Q: Is there any reduction of overall trucks on highways as a result of the 129k program?

A: Reduction in truck traffic varies dependent on the applicant, route, commodities and time of year. Estimates range from 12 percent to 20 percent in reduced truck traffic on approved 129k routes.

Q: How is a 129k route approved?

A: Routes are approved by the Idaho Transportation Board following a thorough review of the route. Reviews consist of route analysis and public involvement. Analysis are conducted by ITD’s Office of Highway Safety, Office of Bridge Asset Management, Division of Motor Vehicles and the applicable ITD District Engineer. Public comments are sought during the review process and are incorporated into ITD’s final evaluation, which is presented to the 129,000 pound Subcommittee. The 129,000 pound Subcommittee reviews the evaluation and either endorses or doesn’t endorse the application. The application evaluation is presented to the Idaho Transportation Board for approval or disapproval of the route. If approved, the route goes into effect 14 calendar days after the Transportation Board approves the application.

Q: Do trucks which are over legal limits require a permit to drive on routes approved for 129,000 pound operations?

A: Yes. When a route is designated a 129k route it means the route has been designated as such and meets all requirements per Idaho Code. All trucks operating on these highways must still be permitted to operate on a 129k approved route per Idaho Rules and Code.

Q: Who grants permits for trucks weighing up to 129,000 pounds on state and federal highways?

A: The Idaho Department of Motor Vehicles is the executive permitting agent for trucks operating on highway systems within Idaho.

Q: Who approves a route for trucks weighing up to 129,000 pounds on local roads?

A: The Local Highway Jurisdiction (LHJ) has the authority to approve a 129k route request for routes within the local highway’s jurisdiction.

Q: Who can apply for a highway to be designated for a 129k use highway?

A: Any company or owner or operator of an overweight or oversized vehicle can apply for a route to be designated as a 129k route.

Q: Who approves a route for trucks weighing up to 129,000 pounds on local roads?

A: The Local Highway Jurisdiction (LHJ) has the authority to approve a 129k route request for routes within the local highway’s jurisdiction.

Q: Won’t heavier trucks go slower on the highways and cause congestion while ascending a hill?

A: Oversized vehicles must abide by Idaho rules and code regarding speed or at safe speeds given road and environmental conditions on highways. Oversized vehicles must maintain a minimum speed limit of 20 mph while ascending any grade.

Q: What are the non-permitted weight limits on interstates and highways?

A: The Federal Highway Amendment Act of 1974 established allowable legal weight limits on Interstate System Highways at 20,000 pounds for single axles, 34,000 pounds on tandems and total gross loads not exceeding 80,000 pounds.

Q: What are the non-permitted weight limits on non-interstate highways?

A: Allowable legal weight limits on non-interstate highways are set at 20,000 pounds on single axles, 37,000 pounds on tandems and total gross loads not exceeding 80,000 pounds.

Q: Can 129k trucks stop as quickly as trucks weighing less?

A: Yes, the additional axles on the 129k trucks are outfitted with brakes providing extra stopping power for trucks compared to 80,000 pounds trucks with fewer axles. Trucks weighing up to 129,000 pounds must comply with maximum allowable stopping distance criteria.

Q: Do trucks authorized to weigh up to 129,000 pounds damage pavement more than trucks weighing up to 80,000?

A: The impact of a 129k on pavement structures is less than an 80,000-pound truck by 21 percent. This is because of disbursement of weight among additional axles and the spacing of the axles allows the weight to spread over a greater area, thus reducing the impact on routes.