U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000
Effective documentation of design exceptions is important for several reasons.
First, agency staff typically complete many projects simultaneously across a jurisdiction. Important decisions such as design exceptions require review, oversight, and approval, usually from multiple levels of management. Requiring complete documentation using prescribed formats and technical references is an effective means of maintaining quality control over decisions and outcomes.
Second, documentation offers an historical benefit for future designers. If a safety or operational problem arises or if the location is being reconstructed, understanding the thought process and reasons for the decisions that were made in earlier projects can be valuable information for designers, particularly where design exceptions were used. For this to be useful, an archive system is needed that allows designers to quickly and easily find historical documentation for decisions made at their project locations.
Third, if a design decision is questioned in a lawsuit and design negligence is alleged, design exception documentation provides proof that the decision was made in a deliberative, thorough manner after fully evaluating the impacts and the alternatives. In most states, designers are afforded some level of discretionary immunity for their design decisions. Regardless of the level of immunity, documentation and retention of such documentation for later reference is essential to limiting an agency’s liability should a lawsuit over design negligence be filed. Crashes and resultant legal action may occur many years after the highway was constructed.
The person who prepares the design exception document is normally very familiar with and knowledgeable about the project and the design. The goal should be to prepare a clear and concise explanation of the design recommendation–one that will provide the person(s) in charge of review and approval, who usually has much less detailed knowledge of the project, enough information to understand the decision and make an informed judgment on whether it should move forward. Length of documentation is not important. The key is to provide clarity and completeness to someone not familiar with the project or the design exception.
Another audience to consider is future designers. They should be able to clearly understand the design team’s reasons for the design exception, even many years after construction.
Documentation should demonstrate the designer’s clear understanding of the design criteria and their functional relationships, the unique context, careful consideration of alternative solutions, and a reasonable weighing of impacts and effects in support of a recommendation to deviate from the adopted criteria. Critical to this documentation and the ultimate recommendation is a record of the consideration and application of strategies and features to mitigate the potential risk of the design exception.
Although the content of the design exception document will vary based on the situation, the following is a list of items and issues to include:
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Basic Information |
Identify the location of the design exception, including the length or beginning and ending points, if applicable. A map or graphic may be appropriate. |
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State the design speed. | |
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State the traffic volumes and the composition of traffic. | |
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Design Element(s) |
State the design element(s) to which the design exception applies. |
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State the minimum value or range. | |
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State the resource that was used to obtain the design value and its year of publication (for example, the 2004 edition of AASHTO’s Policy on Geometric Design of Highway’s and Streets). | |
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State the value being proposed. | |
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Explanation |
Describe the reasons for the design exception. |
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Describe the site constraints. | |
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Describe and, if possible, quantify the costs and impacts involved with fully meeting design criteria. Some costs, such as construction and right-of-way costs, are relatively easy to quantify. Social costs, such as impacts to communities or the natural environment, are more difficult to quantify but are still very important. Use tables, charts, and drawings as appropriate to illustrate and clarify the impacts. | |
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Describe the other alternatives that were considered. | |
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Discuss the potential impacts to safety and traffic operations. | |
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Mitigation |
Describe the mitigation measures that were considered. |
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Describe the mitigation measures that will be implemented. Include drawings if appropriate. | |
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Supporting Information |
For locations where an existing feature that does not meet criteria is being maintained and current crash data are available, quantify the substantive safety of the location and how it compares to similar facilities. |
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If any research or other technical resources were consulted as part of the evaluation process, identify them. |
Many design elements not included in the list of 13 controlling criteria are important for the safety and operation of a highway. Providing a clear zone, turn lanes, acceleration and deceleration length, and barriers that meet current crash test standards are a few examples. Exceptions to non-controlling criteria should be identified, justified, and documented, taking into consideration the effect of any deviation from design criteria on safety. The project files should include this information. The design exception information should be organized to assist in periodic program analysis and archived in a way that it can be easily retrieved in the future.
Because of the different organizational structures at State Departments of Transportation (DOTs) and effective processes already in place for review and approval of design exceptions, a standard national process is not appropriate. The key is to have the design exception document reviewed and approved by an individual or small group that is not part of the design team proposing the design exception (for some agencies, final approval rests with someone with a high level of authority, such as the State Design Engineer). This process allows the design exception to be looked at from a fresh perspective and evaluated objectively. The review step provides a level of quality control and consistency. An independent review also demonstrates a complete process, which can reduce tort liability.
FHWA has review and approval authority for any design exception on the interstate system. For design exceptions on other NHS routes, the role of FHWA Divisions should be defined by written agreement between the Division Office and the State DOT.
