U.S. Department of Transportation
Federal Highway Administration
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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
This magazine is an archived publication and may contain dated technical, contact, and link information.
|Publication Number: Date: March/April 1999|
Issue No: Vol. 62 No. 5
Date: March/April 1999
For highway designers, the 1990s have become the decade of flexibility. From Maryland to Utah, designers are facing the new realities of the 1990s — an increasing number of vehicles on the road coupled with increasing public involvement, community and economic development, environmental sensitivity, historic preservation, neighborhood preservation, and concern for bicyclists and pedestrians.
While more and more people are driving, more people also want to participate in the decisions that affect their lives. And in many cases, the input reflects changing community values regarding the importance of a number of factors and issues related to highway construction. In a growing number of construction and improvement projects, plans for high-speed through routes have been revamped to preserve neighborhoods, protect the environment, provide a more appropriate street for a community, reduce speeds, and provide friendly approaches for bicyclists and pedestrians.
In 1997, Acting Federal Highway Administrator Jane F. Garvey noted that Congress made a strong national commitment to safety and mobility at the same time it made a commitment to preserve and protect the environmental and cultural values affected by transportation facilities.
"The challenge to the highway design community is to find design solutions, as well as operational options, that result in full consideration of these sometimes conflicting objectives," she said.
These following projects, and others around the country, are part of a movement toward flexibility in highway design or context-sensitive design:
Just a decade ago, many of these projects would not have proceeded in the same way. The planners in these cases produced new plans that responded to public concerns about their initial proposals.
This flexibility in highway design started from the bottom up with a growing demand for public participation in transportation decisions, but it has been embraced by top state and national leaders. These leaders are developing new programs to train design engineers in this new approach to highway improvements.
The training and education programs must re-emphasize three critical areas. First, planners and designers must actively seek public involvement at the earliest possible time and throughout the process. Second, they must develop designs that meet the needs of specific sites rather than attempting to use centralized, standardized solutions, recognizing that different communities may have different values and priorities. Third, to meet specific-site needs, they must consider using the flexibility contained in the current design guidelines — or seek a design exception — instead of automatically opting for the high-end solution by giving priority to capacity over environmental, historic preservation, and neighborhood-protection concerns.
The growth in federal road funding during the middle of the 20th century, capped by the Interstate Highway and National Defense Act of 1956, was coupled with the use of nationwide design standards for federally funded projects. These standards were developed by the states through the American Association of State Highway and Transportation Officials (AASHTO) in cooperation with the Federal Highway Administration (FHWA) and applied when the focus of the federal program was construction of interstate highways — a system consisting mainly of intercity connectors built in undeveloped areas.
The era of interstate highway construction was brought to a close by the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA). The focus of the program was expanded to include funding suballocations for urbanized areas; transportation enhancements such as historic preservation and bicycle and pedestrian trails; and new social, environmental, and quality-of-life factors for state and metropolitan planners to consider when approving projects and plans.
ISTEA made the planning, design, and construction of transportation projects part of a broadly-based process in which the movement of vehicles would be weighed against other factors. Planners were required to look at the entire community, its environment, and its unique features when making plans for projects.
ISTEA emphasized the importance of good design that is sensitive to its surrounding environment, especially in historic and scenic areas. ISTEA addressed the issue of context-sensitive design, saying: "If a proposed project ... involves a historic facility or is located in an area of historic or scenic value, the Secretary may approve such project ... if such project is designed to standards that allow for the preservation of such historic or scenic value and such project is designed with mitigation measures to allow preservation of such value and ensure safe use of the facility."
For the new 260,000-kilometer National Highway System (NHS), consisting of the Interstate Highway System and principal arterials, nationwide design standards remained in effect. However, the new law eliminated the requirement for the use of nationwide design standards for non-NHS projects, such as those built under the Surface Transportation Program and Congestion Mitigation and Air Quality Improvement program (CMAQ).
The National Highway System Designation Act of 1995 went even further by allowing flexibility on NHS roads except for the Interstate Highway System. It said, "A design for new construction, reconstruction, resurfacing ... restoration, or rehabilitation of a highway on the National Highway System (other than a highway on the Interstate System) may take into account ... [in addition to safety, durability, and economy of maintenance] (A) the constructed and natural environment of the area; (B) the environmental, scenic, aesthetic, historic, community, and preservation impacts of the activity; and (C) access for other modes of transportation."
AASHTO has adopted and issued the design criteria followed by state highway departments. The 1994 edition of AASHTO's Policy on Geometric Design of Highways and Streets ("the Green Book") is the most current design guide, and appropriate parts have been adopted by FHWA as a national standard for NHS projects.
The policy provides ranges of values for critical dimensions in highway and road design. Use of the Green Book provides consistency in safety and operational efficiency of highways and roads throughout the nation. This consistency also provides some comfort and convenience to motorists who do not have to deal with varying roadway characteristics as they travel from state to state.
The AASHTO Green Book guidelines have been used as the final word in most highway design for the past 50 years. However, it was not intended that they limit the ability of engineers to design for site-specific needs or opportunities. AASHTO stresses the need for thoughtful design to mitigate traffic and resultant environmental impacts. Congress has, through ISTEA, aided this effort by providing flexibility to the states to develop their own criteria for non-NHS projects.
Function vs. Aesthetics
Because "vehicle-miles traveled" (VMT) continue to increase rapidly in the United States, designers find their first concern to be wider lanes and shoulders with straighter, flatter alignments to obtain the highest capacity for the roadway. These roadway features often clash with the aesthetics of the urban neighborhood; the narrow, tree-lined country lane; and the covered bridge.
The challenge to designers has grown in the past decade. As traffic increases on our nation's highways, congestion brings angry complaints from motorists who want safe, fast, well-maintained highways. Growing congestion has led to greater driver anger and even "road rage." However, there is also growing demand by neighborhood groups, environmental activists, other interest groups, and ordinary citizens for involvement in the decision-making process. These groups often give priority to the protection of historic and natural resources, commercial areas, and residential neighborhoods over the high-capacity designs.
The environmental impacts of a roadway are often the dominant characteristics perceived by the community living in its immediate vicinity. In a survey conducted after the construction of an urban freeway, community members were asked to rank the most important characteristics of the new highway. Those individuals living adjacent to the highway ranked noise, fumes, and appearance as the top three characteristics, and they ranked congestion, design standards, and travel times at the bottom. Those living away from the freeway listed the characteristics in the exact opposite order.
Often the terrain through which the highway passes constrains its design. Vehicle speed is directly related to the degree of the highway's horizontal and vertical curve. High speeds increase the time it takes for a vehicle to stop on the highway. The "stopping sight distance" is decreased by steep vertical curves or tight horizontal curves. Thus, higher speeds may require significant alteration of the natural terrain to provide the flat horizontal and vertical curves necessary for the motorist's safety. This alteration may not only remove individual items or areas of environmental importance, it also tends to smooth out the natural terrain, creating a less interesting and less aesthetic environment through which to drive.
Maintenance of uniform speed along the highway provides additional safety based on driver expectation. Tightening curvature to avoid natural areas or areas of social interest requires lessening the design speed in that area. This causes a speed differential on adjacent segments of the highway. The greater the differential and the more often differentials occur, the greater the potential for crashes on that highway.
The width of the highway right-of-way includes not only the width of the pavement itself, but it must allow for adjoining drainage facilities, roadside utilities, and a "clear zone." This zone is to remain clear of obstacles that will damage a vehicle on impact — including trees, fences, rocks, and other elements of a scenic view. Highway designers use information in the Green Book and the AASHTO Roadside Design Guide to determine the appropriate width of the clear zone for highways. The Green Book also indicates the maximum degree of acceptable slope. While steep slopes minimize the necessary right-of-way, they are a major factor in the overturning of vehicles that have left the roadway.
Most design engineers have traditionally viewed solutions that solve capacity problems as their top priority, and thus, the high-end solutions have usually won out. Despite the context-sensitive language in ISTEA and the NHS Designation Act, the flexibility allowed by the Green Book and the option of design exceptions have been used only on a limited basis.
FHWA and the States Reach Out
In 1997, FHWA joined forces with AASHTO and other interested groups to design a companion guide to the Green Book, entitled Flexibility in Highway Design, published in July 1997. This partnership included groups such as the Bicycle Federation of America, the National Trust for Historic Preservation, and Scenic America. The concepts expressed in the guide reflect the mission, goals, and direction of FHWA's strategic plan.
"Design can and must play a major role in enhancing the quality of our journeys and of the communities," Garvey wrote in the guide's opening message.
"The guide builds on the flexibility in current laws and regulations to explore opportunities to use flexible design as a tool to help sustain important community interests without compromising safety. To do so, this guide stresses the need to identify and discuss those flexibilities and to continue breaking down barriers that sometimes make it difficult for highway designers to be aware of local concerns of interested organizations and citizens," she continued.
Garvey cited the importance of sharing "ideas for proactive, community-oriented designs for transportation facilities." She said, "We encourage designers to become partners with transportation specialists, landscape architects, environmental specialists, and others who can bring their unique expertise to the important task of improving transportation decision-making and preserving the character of this nation's communities."
"We can encourage creativity, while achieving safety and efficiency, through the early identification of critical project issues and through consideration of community concerns before major decisions severely limit design options," Garvey said.
The guide's purpose is to provide examples, ideas, and options on which the planners and designers can draw to produce better, more environmentally sensitive projects. It stresses the importance of project scoping, community awareness, interdisciplinary decision-making, and early public participation. It covers the areas of functional classification, design controls, horizontal and vertical alignment, cross-section elements, bridges, and intersections.
The guide shows that having a process that is open, includes public involvement, and fosters creative thinking is an essential part of achieving good design. It is an aid for highway designers, environmentalists, and the public to identify possible approaches that fully consider aesthetic, historic, and scenic values, along with safety and mobility.
The guide cites the options available to state and local highway officials to achieve a balanced road design, such as:
The first three stages of a project — planning, project development, and design — are the most important in determining the final design features of the project. Decisions made in the early stages can limit the flexibility available in the later design stages.
Community involvement is an absolutely critical factor. As the guide states, "Obtaining a community consensus on the problem requires proactive public involvement beyond conventional public meetings at which well-developed design alternatives are presented for public comment. If a consensus cannot be reached on the definition of the problem at the beginning, it will be difficult to move ahead in the process and expect consensus on the final design."
During the planning and project development stage, planners must resolve the issues of the impact of the project on the general physical character of the area; the impact on any unique historic or scenic characteristics; and the concerns of the community about safety, capacity, and cost.
A successful highway design process includes early and continuous public involvement, the use of visualization techniques to aid the public, early and continuous use of a multidisciplinary design team, and the application of flexible and creative design criteria. The multidisciplinary team may include traffic engineers, ecologists, transportation and urban planners, social scientists, landscape architects, architects, urban designers, historians, biologists, archaeologists, geologists, and artists.
The guide emphasizes the existing flexibility in state standards along with the option of design exceptions when the state standards do not cover the needs of a specific project. Design exceptions are used by state highway agencies when unusual circumstances such as highly sensitive resources or extreme cost or safety concerns warrant the use of less than the lowest Green Book standards. For example, if a rock escarpment prevents full shoulder widths in a narrow mountain pass, a design exception for narrower shoulders might be made in lieu of expensive blasting that also creates an ugly slope and that may be difficult to safely maintain.
Interest in the approach described in Flexibility in Highway Design has been great. FHWA has already distributed more than 15,000 copies of the manual, which has gone to a second printing.
Thinking Beyond the Pavement
As the next outreach step, FHWA and AASHTO joined in May 1998 with the Maryland Department of Transportation and Maryland State Highway Administration to sponsor "Thinking Beyond the Pavement," a national workshop on integrating highway development with communities and the environment while maintaining safety and performance. The 325 participants included chief engineers, senior designers, and planners from 29 state departments of transportation; representatives of national transportation organizations; and a variety of stakeholders from government, the private sector, and citizens' organizations.
The conference produced two major agreements: first, a consensus on the qualities of projects and the characteristics of the highway development process that could integrate transportation facilities with communities and the environment, and second, actions to overcome barriers to context-sensitive design, to educate transportation officials and stakeholders on this approach to design, and to encourage its application to all projects.
There was agreement on the qualities of excellence in transportation design. There must be an early agreement on a project that satisfies the purpose and needs of a full range of stakeholders. The project must be safe for the user and the community; be in harmony with the community; preserve environmental, scenic, aesthetic, historic, and natural resource values; exceed expectations; involve efficient and effective use of time, funding, and community resources; be built with minimal disruption to the community; and add lasting value to the community.
There was also agreement on the characteristics of the process that would yield excellence. This process would include early and continuous communication with all stakeholders; early establishment of a multidisciplinary team; involvement of a full range of stakeholders in the scoping process to develop a consensus on the purposes of the project; examination of multiple alternatives to produce consensus on approaches; a commitment to the process from top agency officials and local leaders; a public involvement process, including informal meetings; understanding of the landscape, the community, and valued resources before engineering design is begun; and the use of a full range of communication tools.
The conference also produced a list of specific recommendations with suggestions on who should undertake them.
The states were urged to:
Following the session, Federal Highway Administrator Kenneth R. Wykle said that FHWA will work closely with the conference sponsors to sustain the momentum generated by the conference.
"The conference was truly on target by bringing together a variety of interests and putting them to work to solve highway development issues. Our success in this effort will help us to provide better transportation solutions as well as to improve the overall quality of life in our country," said Wykle.
Tom Warne, executive director of the Utah Department of Transportation, chairs AASHTO's Standing Committee on Highways, and he has been one of the leading advocates of flexible design.
"We not only need transportation facilities, but they must enhance the community. They must respect cultural, historic, and environmental values. We have had the flexibility to do these things, but with the construction of the interstate system, everything had to meet uniform standards, and efficiency standards were the priority. Now we have to recognize all these other factors," he said.
"The Green Book has all the flexibility you need," Warne declared. "Experienced designers were less inclined to deviate from the standards they were accustomed to using. But now, many of those designers have begun to retire, and we have new people doing the designs. This is an idea that five years ago we couldn't have made happen."
Following up on the Maryland workshop, AASHTO is working on what Warne called "bridging documents" to link the discussions on safety and liability in the Green Book and in Flexibility in Highway Design. He hopes to have the bridging documents completed by late 1999.
"The biggest issue is liability. States want to know if you can do this without exposing yourself to major liability. When that kind of issue is involved, everyone will proceed cautiously," Warne said.
AASHTO will also sponsor five pilot states — two in AASHTO Region one and one each in regions two, three, and four — to implement the context-sensitive design procedures and to train the other states in their regions. These five states — Connecticut, Kentucky, Maryland, Minnesota, and Utah — will take the lead in incorporating the principles of flexibility into the project development and design processes.
In November 1998, the AASHTO Standing Committee on Highways adopted an amendment to its strategic plan to add a strategy to "develop and advocate guidelines and best practices to assure appropriate coordination with cooperative planning organizations, local governments, and with other modes of transportation, thereby satisfying the project purpose and needs of a wide range of stakeholders."
The actions to promote this strategy will be: a report in mid-1999 by a task force on the coordination issues and best practices of planning organizations and local governments; an April 1999 report by the National Cooperative Highway Research Program on best practices for coordinating with metropolitan planning organizations, local governments, and other modes; a partnership beginning later in 1999 with stakeholders to educate designers, public officials, constituent groups, and citizens about the project development process, existing flexibility, and context-sensitive design; an evaluation in October 1999 of the recommendations of the Thinking Beyond the Pavement workshop; and a resource document in October 1999 on the legal implications of design exceptions and strategies for states to limit liability.
Warne cited two instances in Utah where context-sensitive design changed the nature of projects. First, he said a new main street for rural Ridgefield had to be scaled back. "The concrete street would have changed the nature of the rural community." Second, changes were made in a traffic signal project near the state capitol in Salt Lake City. "The original plan would have changed the nature of the historic community and forced the taking of residences. The new design allowed us to preserve neighborhoods."
Context-Sensitive Highway Design Workshop
|A workshop on context-sensitive highway design will be held June 17 and 18, 1999, at the Sheraton Reston Hotel in Reston, Va. The conference is sponsored by ASCE, AASHTO, FHWA, and others.|
|The conference provides an opportunity to be a part of the expanding movement toward context-sensitive highway design. The objective is to expose transportation engineers and executives from consulting firms; local, state, and federal government; and community advocacy organizations to the concept of context-sensitive design, provide information on ongoing AASHTO initiatives in this area, and encourage discussion and debate on the role of the civil engineer in advancing context-sensitive design.|
|The mailing address of the hotel is Sheraton Reston Hotel, 11810 Sunrise Valley Drive, Reston, VA 20191-4400|
|For more information contact: Sandra Hayes, FHWA, (501) 324-5625
Mike Hewitt, ASCE, (703) 295-6115
Flexible Design for the Future
Building on the FHWA and AASHTO initiative, the American Society of Civil Engineers (ASCE), along with FHWA and AASHTO, is sponsoring a June 1999 workshop on context-sensitive highway design. The two-day workshop will feature ASCE, FHWA, and state officials speaking on the issue, panel discussions, and group discussions of two case studies.
The goal of the workshop is to "mainstream" the concept of context-sensitive design — not only for state highway agency officials but also for the consultants who work with them.
The workshops, training, reports, and studies are part of a concerted effort to change the thinking of highway designers. For many years, states patterned their design processes after FHWA procedures. The result was mostly decisions to work at the high end of the range of options. The training will let designers know they can look at other options. It will encourage the use of interdisciplinary resources.
There are states with procedures that should be changed. These states must look at their existing processes, ask whether they constrain flexibility, and determine what steps they have to take. ISTEA allowed states to design their own procedures for non-NHS projects, but many states have not picked up on that flexibility. They have the opportunity now to make the changes. Many states have centralized decision-making. They have to begin looking at the needs of specific sites.
Flexibility in Highway Design came about because Secretary of Transportation Rodney E. Slater and Acting Administrator Garvey wanted to respond to the flexibility language in ISTEA and the NHS Designation Act. They believed that FHWA should be a broad-thinking agency that looks beyond just transportation facilities. Slater and Garvey decided to take the opportunity to respond to the congressional impetus by promoting the implementation of flexibility in design.
It was a theme that was compatible with the way in which they were trying to change the federal highway program. They believed that the language of ISTEA marked a new era in transportation. Slater, first as federal highway administrator and now as secretary of transportation, has repeatedly stated, "Transportation is more than concrete, steel, and asphalt — it's about people."
Harold E. Peaks is the team leader for the Community Impacts and Transportation Enhancement Team, Office of Environment and Planning, FHWA. He has managed the team responsible for flexibility in highway design, community impact assessment, transportation enhancements, public involvement, and environmental justice since mid-1996. He coordinated the development of the Flexibility In Highway Design publication, is an FHWA representative on the Steering Committee for Context-Sensitive Design, and works closely with organizations such as the Transportation Research Board and AASHTO on related programs. Peaks joined FHWA in 1978, and his career has included assignments in environmental policy, community impact assessment, project development, public involvement, and National Environmental Policy Act (NEPA) analysis. Prior to FHWA, Peaks worked in planning with the Pennsylvania Department of Transportation. He has a bachelor's degree in economics from Lincoln University in Pennsylvania and a master's degree in transportation planning from Trinity University in San Antonio, Texas. He has also done post-graduate work in administration at the University of Maryland.
Sandra Hayes is assistant division administrator for the Arkansas Division of FHWA. Her career with FHWA has also included field assignments in Colorado and Arizona and working in the Environmental Operations Division of FHWA's headquarters. Before joining FHWA in 1987, she worked for the Washington State Department of Transportation, Seattle City Light Department, and the T.A.M.S. and Entranco consulting firms. Ms. Hayes has a bachelor's degree in civil engineering from Montana State University and a master's degree in environmental management and public policy from The George Washington University. She is a registered professional engineer in the state of Washington. She is a member of the American Society of Civil Engineers (ASCE) and vice chair of ASCE's Environmental Quality Committee (Highway Division).