KLK578 Guidance to Assist Local Highway Jurisdictions in Evaluating 129,000 Pound Route Requests
ITD Research Project 250; Task Order Number UI-16-02
Principal Investigators
- Ahmed Ibrahim
- Richard Neilsen
- Ahmed Abdel-Rahim
ITD Project Manager
- Jeff Marker
FHWA Project Advisor
- Lori Porreca
Student Researchers
- —
Research Problem Statement
A significant number of local highway jurisdictions in Idaho lack the engineering expertise and financial resources to conduct detailed assessments when requests are received to increase weight allowances for local roadways beyond the current legal limit for gross load weight of 80,000 pounds. Idaho Code 49-1004A (1) states "the authority having jurisdiction may designate routes ... for vehicles not exceeding ... 129,000 pounds, utilizing criteria established by the board based upon road and bridge structural integrity and engineering standards". These higher load limits can enable private freight organizations to better compete in domestic and global markets by allowing them to distribute freight more efficiently. The Idaho Transportation Department has the engineering staff and database resources available to evaluate road and bridge capacities on state and federal highways; however, local highway districts may not have such resources. This limits the local districts' ability to expeditiously consider increased load requests, which in turn limits freight organizations' ability to operate more efficiently on rural highways resulting in less competitive Idaho industries. Additionally, many local roadways are not designed or constructed to accommodate any type of heavy load. This collaborative study between the Idaho Transportation Department and the Local Highway Technical Assistance Council would provide local highway jurisdictions guidance for conducting roadway assessment from review of available data and current condition to full engineering studies where appropriate.
Project Objectives
The primary objective of this project is to further develop guidance outlining procedures that can be used by local highway jurisdictions to evaluate 105,500 and 129,000 pound route requests. Procedures are expected to vary depending on the characteristics of the roadway. In some instances, full engineering analysis will likely not be required, but the guidance should aid local agencies in determining the level and process of review or engineering study that would be needed to evaluate requests. However, a safety analysis is necessary in every request.
Project Tasks
- Review legal requirements in Idaho regarding truck size and weight limits, including permit provisions and requirements for route designation.
- Review of currently available information regarding the permitted load and 129,000 route request process. This would include a brochure developed by LHTAC, the 129,000 routes website developed by ITD, and ITD procedures for evaluating requests.
- Describe the varying truck configurations possible on routes subject to the legal weight limit of 80,000 pounds and on routes with permitted load limits of 105,500 pounds and 129,000 pounds. Assessment should include truck axle weight criteria and Equivalent Single Axle Load (ESAL) impacts along with length, width and height criteria.
- Enhance the current process to include step-by-step procedures that can be used to evaluate requests to increase load limits on local routes. This would include identifying the types of data needed, resources available to perform assessments, and the factors to consider and the criteria to use in evaluating potential impacts. More specifically, the process should include:
- Consideration of traffic volumes and capacity (AADT, CAADT, design volume, speed limits) and how to obtain that information.
- Review of roadway geometrics (lane width, shoulder width, road grades, road curvature) and how to obtain that information.
- Consideration of possible truck configurations and dimensions (vehicle length, width, height) under various weight limits, including impacts on axle weights and the extent of off-tracking.
- Evaluation of available crash data
- Examination of bridge and highway structure length and capacity for existing and proposed axle weights and truck axle configurations (ITD's Bridge Section can generally perform necessary analysis for structures greater than 20 feet in length). Identification of criteria for determining if an evaluation of structures less than 20 feet in length is required.
- Review of pavement condition/deficiencies and comparison of axle weights for varying truck configurations expected under current and proposed weight limits. Identification of criteria for determining when more in-depth pavement design and condition information, including information on soil characteristics and base materials, is necessary to assess the impact of raising weight limits.
- Prepare a concise guidance document for use by local highway jurisdictions for evaluating requests to increase truck weight limits. The document would include discussion of legal requirements, explanation of feasible truck configurations and axle weights under the different legal and permitted weight limits, and discussion of the recommended step-by-step process for evaluating requests.
- Prepare curricula for a short training could be delivered by LHTAC trainers in the T2 Center to introduce local agency personnel to the guidance materials and provide instruction regarding the evaluation of requests to increase weight limits on local roadways.
Project Communication Schedule
Monthly progress reports will be submitted to ITD.
Researchers will meet with the Project Manager and Technical Advisory Committee either face-to-face or via telephone/webinar every 1-2 months to discuss progress on the work and to review deliverables. Meeting dates and times will be scheduled collaboratively by the Ul's Principal Investigator and ITD's Project Manager.
Needs and Requirements
Upon the start of the project, ITO will provide U of I and will assist the Pl's in with access to the latest data on truck configurations, axle numbers, axle loads, overall dimensions, number of trailers and any other data needed like traffic volumes, capacities and crash data.
Required Outputs/Deliverables
- The key deliverable of the project would be an in depth guidance document for use by local highway jurisdictions that walks them through procedures necessary for evaluating 129,000 pound route requests. The document produced through the research must be clear and understandable to lay readers. In addition, the document needs to provide guidance on when a full engineering analysis is warranted and the types of work required.
- As part of the project, researchers will also develop curricula for a short training course that could be delivered by LHTAC trainers in the T2 Center to provide instruction to local agency personnel in the use of the guidance materials and the evaluation of requests to increase weight limits on local roadways.
Implementation
The guidance document will be distributed to local agencies by LHTAC. In addition, it is expected that LHTAC will use curricula materials developed by the researchers to provide training to local agency personnel regarding review procedures.
Expected Outcomes/Savings to ITD
This project will allow local highway jurisdictions to assess 105,500 and 129,000 pound trucking requests on local roadways which will then connect to the state and federal highway systems allowing for more efficient freight movement Increasing truck load limits from 80,000 pound to 105,500 or 129,000 pounds provides significant increase in freight loads and potentially reduces the number of trucks using the highway system. Overall, this increases the economic benefit to the regions businesses while reducing roadway use and congestion. Such actions will ultimately keep Idaho industries competitive in the national and international marketplace.
Monthly Progress Reports (ITD 771) and Task Progress Charts
Project status:
Active
Draft report:
Due July 2016
Final report:
Due September 2, 2016