Chapter Four - Section 1: Introduction
The implementation of a statewide trail system requires consistency of quality and design throughout Iowa. Trail users from across the state and throughout the nation should be able to expect a safe, user-friendly, and accessible trail no matter where in Iowa they travel. In order to encourage the implementing agencies and organizations to create high-quality trail facilities, the Iowa Department of Transportation (Iowa DOT) has compiled a series of design guidelines. These guidelines will be primarily applied in the implementation of trails in the statewide system and other trails that receive funding through the Iowa DOT, but they may also be useful as a design guide for other local trail initiatives.
Trail guidelines are recommendations set forth to help agencies, local communities, and trail organizations to locate, design, interpret, and maintain trails. Because they are based on guidelines established by the American Association of State Highway and Transportation Officials (AASHTO), the Federal Highway Administration (FHWA), the U.S. Architectural and Transportation Barriers Compliance Board (U.S. Access Board), and other state agencies and trail organizations, these guidelines can be considered the best practice recommendations possible. Deviations from the design guidelines will require documentation to the Iowa DOT if the project is funded through the Iowa DOT.
The limitation of design guidelines lies in the fact that any accepted guideline will have exceptions, necessitated by local conditions, community desire, changing trends, intensity of use, and many other factors. The strength of design guidelines, however, is that they offer an easy-to-use summary of extensive design expertise, and they allow for flexibility in dealing with site-specific issues without the rigid process associated with design standards. Trail design guidelines should be considered in light of site-specific issues. Each trail project must consider which design guidelines are applicable, and under what conditions the trail should deviate from the guidelines in order to increase user safety or decrease impact to existing conditions.
When planning trails, agencies should strive to create environments and experiences that are inclusive of all people. To ensure that Iowa’s trails meet the needs of all potential users, these design guidelines address a broad spectrum of ability levels and routinely integrate the needs of children, older adults, and people with disabilities. In addition to following these recommendations, designers are encouraged to directly involve trail users of all abilities and ages within their community early on and throughout the trail development process.
The Iowa Trails 2000 design guidelines are established to help accomplish the following goals:
- Increase user safety by recommending appropriate trail widths, sight lines, clear zones, and other design considerations.
- Increase user comfort by recommending trail widths, rest areas, trail surfaces and other elements that contribute to a positive user experience.
- Promote universal access by developing trails that are beneficial to users with a broad range of skill levels and abilities, including people with disabilities, children, and older adults.
- Promote statewide consistency by setting forth one set of guidelines and encouraging trail implementers to follow them wherever possible.
- Reduce cost and increase ease of facility maintenance by recommending trail widths, access points, and other elements that accommodate maintenance equipment and crews.
- Reduce liability by following generally accepted design guidelines being used with success nationwide.
- Ensure compatibility with roads and highways by setting forth specific guidelines for trail facilities within highway rights-of-way, including bicycle lanes and paved shoulders.
- Recognize various user modes by setting forth specific guidelines relating to walking/hiking, bicycle, in-line skating, equestrian, snowmobile, off-highway vehicle, motorcycle, and canoe trails.
- Recognize various user skills by recommending different trail types for different skill levels, especially in the case of bicycle trails.
- Minimize impacts to natural resources and private land by setting forth recommendations for trail location and mitigation strategies.
- Ensure the long-term viability of trails by recommending good planning and design practices.
Users of the Design Guidelines
The Iowa Trails 2000 statewide trails vision will be planned, designed, and implemented by state agencies, local governments, and trail groups. The usefulness of these design guidelines, therefore, extends far beyond the Iowa DOT. The following groups are likely to use the Iowa Trails 2000 design guidelines:
- Policy-makers at various levels will use the design guidelines to plan for future trail development, especially relating to right-of-way or easement acquisition and corridor preservation.
- Trail planners, both public entities and private consultants, will use the design guidelines to make recommendations for roadway crossings, possible corridors, accommodation of various user modes, and other issues.
- Trail designers, including private consultants, will use the design guidelines in the construction documentation process when dealing with trail alignment, profile, width, cross-section, and surface.
- Concept/application reviewers will use the design guidelines to evaluate the trail for funding. As stated above, deviation from the design guidelines is possible, but priority may be given to trails that follow the design goals of the statewide system.
- Trail maintenance and operations agencies/ organizations will use the guidelines in the day-to-day operation of the trail by maintaining appropriate clear zones, surface condition, and access points.
Many national and state agencies and plans have set forth design guidelines. Oftentimes, these guidelines, as in the case of those written by AASHTO, are the result of extensive testing and evaluation. They are, therefore, an invaluable resource for trail planners and designers. The Iowa Trails 2000 design guidelines rely heavily on these resources, adapting them, where necessary, to specific conditions and policies in the state of Iowa. Major sources of design guidelines include the following documents.
- Guide for the Development of Bicycle Facilities, American Association of State Highway and Transportation Officials (AASHTO): 1999 (hereafter referred to as the AASHTO Guide). This is the recognized standard for bicycle design guidelines. Updated in 1999, this document contains the most current recommendations available. In addition, trails which will receive federal transportation funding must adhere to these AASHTO guidelines.
- Manual on Uniform Traffic Control Devices
- A Policy on Geometric Design of Highways and Streets "Green Book," AASHTO. This resource offers design details for Interstate and Primary Road design.
- Iowa Design Manual, Iowa Department of Transportation, Office of Design. This document offers details and procedures for the design of transportation facilities in Iowa.
- Recommendations for Accessibility Guidelines: Outdoor Developed Areas Final Report, U.S. Architectural and Transportation Barriers Compliance Board (U.S. Access Board): 1999. This document is the final report of the Regulatory Negotiation Committee on Accessibility Guidelines for Outdoor Developed Areas. This committee developed accessibility recommendations through a consensus process for a variety of outdoor areas, including trails. The U.S. Access Board will use the committee’s recommendations, in conjunction with public comment, to develop standards for compliance with the Americans with Disabilities Act (ADA). Until standards are developed, this report contains the best information for meeting the requirements of the ADA.
- Designing Sidewalks and Trails for Access: Part II of II: Best Practices Design Guide, Federal Highway Administration (FHWA): 2000. This document provides detailed planning and design recommendations for developing pedestrian and non-motorized multi-use trails that meet the needs of a broad spectrum of users, including people with disabilities. This document also contains background information regarding user needs, the benefits of universal design, and recreation equipment used by people with disabilities.
- Selecting Roadway Design Treatments to Accommodate Bicycles, Federal Highway Administration: 1994. This is primarily a planning document for bicycle facilities, but also offers general design guidelines. This document makes frequent reference to the AASHTO Guide described above.
- Minnesota Bicycle Transportation Planning and Design Guidelines, Minnesota Department of Transportation: 1996. This document offers both planning guidance and design guidelines. It is nationally recognized for its detailed guidelines dealing with roadway crossings.
- Oregon Bicycle and Pedestrian Plan, Oregon Department of Transportation: 1995. This is a detailed, well-organized planning and design guide. It is known for innovative recommendations for pedestrian and bicycle accommodation with traffic calming and expressway interchanges.
- Portland Pedestrian Design Guide, City of Portland, Oregon, Office of Transportation: 1998. This guide focuses on the accommodation of pedestrians in urban areas.
- Hennepin County Bicycle Transportation Plan, Hennepin County, Minnesota, Department of Public Works: 1996. This document gives an extensive array of guidelines for the implementation of bicycle facilities within road rights-of-way.
- Trailbuilding Basics, International Mountain Bicycling Association.
- General Guidelines for In-line Skating Trails, Rollerblade In-line Skate Association.
- National Park Service Trails Management Handbook, United States Department of the Interior, National Park Service: 1983.
- Motorized Trails: an Introduction to Planning and Development, Pennsylvania Department of Environmental Resources, Bureau of State Parks: 1980.
- Iowa Snowmobile Trail Manual, Iowa Department of Natural Resources: 1987.
- AMC Field Guide to Trail Building and Maintenance, Robert D. Proudman and Reuben Rajala, Appalachian Mountain Club: 1981.
- A Guide to Off-Road Motorcycle Trail Design and Construction, American Motorcyclist Association: 1984.