Final Scope

Low volume road (LVR) networks function as the primary link to highway transportation systems as well as the connection of communities. The structural capacity of LVRs plays a vital role in providing competent, stable, and durable roads. While state departments of transportation (DOT's) and the Federal Highway Administration (FHWA) have invested significant resources on improving the structural design of high-volume pavements, the structural design of LVRs, particularly local access roads in rural areas, often goes overlooked. LVRs built following a template design or minimum local standards may be sufficient for passenger vehicles, but once LVRs are subjected to heavy traffic from agriculture, renewable and non-renewable energy development, or logging operations the structural capacity of LVRs is compromised and severe damage occurs. The damage from heavy loads can be further exacerbated by seasonal impacts such as spring thaw.

When designing pavements for LVRs, many LVR owners and managers follow the AASHTO design guide, which converts axle loads into equivalent single-axle loads (ESALs) by using load equivalency factors (LEFs). However, these design practices may not adequately account for heavy loads (i.e., overweight standard trucks and nonstandard axle-configurations) nor were they developed to provide designs for all types of LVRs. LVRs that experience a high percentage of heavy standard trucks and overweight non-standard traffic and commensurately high loads suffer rapid and premature road deterioration. Such failures are often attributed to overweight loads applied to a substandard road design.

The objective of this synthesis is to document current state DOT practice for the structural design and evaluation of paved and unimproved LVRs, particularly those exposed to heavy loads. 

Information to be gathered includes (but is not limited to)

• State DOTs’ responsibility for design, evaluation or permitting of paved or unpaved LVRs;
• Definition of LVRs;Percentage of state roads that are LVRs;
• Definition of heavy loads for LVRs;
• Existence of written pavement design guidelines or specifications for LVRs;
• Typical structural design of LVRs;
• Design modifications for LVRs supporting heavy loads (e.g., overweight trucks, non-standard heavy traffic);
• Specific permitting requirements for LVRs;
• Impacts of heavy loads on LVRs and the primary causes of structural failure of overloaded pavement sections;
• Performance monitoring methods of LVRs with heavy loads (e.g. pavement management system);
• The role and impact of spring-time load restrictions on LVRs.

Information will be gathered through a literature review, a survey of state DOTs, and follow-up interviews with selected DOTs for the development of case examples. Information gaps and suggestions for research to address those gaps will be identified.

Information Sources (Partial)

• Coghlan, G. T. (2000). Opportunities for Low-Volume Roads. Transportation Research Board CD.
• Sebaaly, P. E., Siddharthan, R., and Huft, D. (2003). “Impact of Heavy Vehicles On Low-Volume Roads.” Transportation Research Record 1819(1), 228-235.
• Wilde, W.J. (2014) “Assessing the effects of heavy vehicles on local roadways.” MnDOT, 2014-32.

TRB Staff
Zhiye Li
Email: Zli@nas.edu

Meeting Dates
First Panel Meeting: 12/11/2024 (Virtual, via Zoom)
Teleconference with Consultant: 01/14/2025 (Virtual, via Zoom) 
Second Panel Meeting: 09/17/2025 (In-person, in Washington, DC)

Panel Members
Seonghwan Jacob Cho, Indiana Department of Transportation
Sanghyun Chun, Arkansas Department of Transportation
Laura E. Fay, Western Transportation Institute
Nusrat Siraj Morshed, New Jersey Department of Transportation
Hadi Nabizadeh, California Department of Transportation
Tom "Thomas" Yu, Federal Highway Administration (FHWA)