131.4 Design Exception Process
|Design Exception Information Form|
220.127.116.11 When to complete a design exception
A design exception is encouraged wherever the potential for additional value lies outside of written engineering policy. They should not be considered breaches of policy as much as opportunities to add practicality to design.
Exceptions are not requests for permission; rather, they simply document deliberate variances from engineering policy. It is equally important to document those variances that exceed written standards as well as those that fail to attain them. That is not to say a designer should attempt to exceed policy although such a course of action is, at times, the most practical solution.
Documentation of a design exception is necessary for MoDOT to defend itself from litigation. Litigation may take place many years after the actual construction of an improvement. Permanent documentation is necessary to determine the justification for the design exception.
A design exception consists of items that vary from preferred criteria for the design of an improvement. In most cases the need for an exception is the result of an inability to reasonably meet the preferred design criteria. However, there are occasions where specific design elements for a project may exceed the normal criteria recommended for the type of improvement. These variations must also be documented through the design exception process. When there is doubt if a design exception is required, the Design Division liaison engineer is to be consulted.
18.104.22.168 How to complete a design exception
When the need for a design exception has been identified, the appropriate person (listed below) is responsible for completing the standard Design Exception Information Form. Use of this form is more effective official documentation than a casual notation. The form must include a detailed description of the rationale for the change.
After completion of the form, the order of approval by transportation officials, for each project category, is given below. A copy of every design exception is provided to the Design Division for the permanent project file. A copy of the form is also kept in the district file.
Full FHWA Oversight Projects
- district project manager
- district engineer
- State Design and/or State Bridge Engineer
Exempt Roadway Projects
- district project manager
- district engineer
Exempt Bridge Projects
- district project manager
- district engineer
- State Bridge Engineer
Consultant Designed or Cost Share Projects
- consultant or local public agency
- appropriate project-specific path shown above
The Federal Highway Administration (FHWA) reserves the right to audit the design exceptions of any federal aid project regardless of level of oversight.
The request for travelway design exceptions must be initiated and signed by the project manager in charge of the project. The project manager will submit the design exception information form to the district engineer and following approval to the Design Division as necessary.
If a consultant is designing the project, their project manager will initiate the request and sign the design exception form first and then submit it to the district project manager. All consultant design exceptions are reviewed by the district and signed by the district's project manager prior to submittal to the district engineer and following approval to the Design Division as necessary.
Design exceptions that contain only bridge related items are initiated by the Bridge Division and should adhere to the following process:
- 1. The Bridge Division prepares the design exception information form. NOTE: the structural project manager does not sign this form.
- 2. The design exception is reviewed and/or approved by the State Bridge Engineer.
- 3. The structural project manager transmits the signed design exception information form to the district project manager for review and signature.
- 4. The district project manager will submit the design exception information form to the district engineer and the Design Division as necessary for final processing.
- 5. The Design Division will be responsible for obtaining approval signatures as necessary and furnish the district and the Bridge Division with copies of the final approved document.
Design exceptions that contain both travelway and bridge related items will adhere to the following process:
- 1. The Bridge Division completes the information related to the bridge items on the design exception form. NOTE: the structural project manager does not sign this form.
- 2. The structural project manager will transmit, electronically if possible, the design exception information form to the district project manager for review.
- 3. The district project manager will add the information related to the travelway items and sign the form.
- 4. The district project manager will submit the design exception information form to the district engineer and the Design Division as necessary for final processing. This will include signature by the State Bridge Engineer and the State Design Engineer.
- 5. The Design Division will be responsible for obtaining approval signatures as necessary and will furnish the district and the Bridge Division with copies of the final approved document.
Requests for design exceptions are made when the need first arises; specifically at submittal of the conceptual study, preliminary plan, right of way certification, or plans, specifications, and estimate (PS&E).
Whenever desired design criteria cannot be met, data for only those non-standard items is listed. This data includes the existing feature (if applicable), the desired design criteria for that feature, the proposed feature, and the location of the feature. The column shown for existing features is not applicable to new construction. The appropriate values for desired design criteria are shown in the second column. The design criteria for new construction on rural and urban highways are stated in individual articles pertaining to each geometric element discussed in Section 200 of this document. Design criteria for 3R and 4R projects are discussed in Section 128 of this document. The criteria for proper access management can be found in MoDOT’s Access Management Guidelines. A Design Exception Information Form is not required if all desired design criteria are used for the improvement project.
All requests must contain reasons to justify the exceptions. It is imperative that the justification be sufficiently complete to clearly reflect that the designer exercised reasonable care in the selection of a particular highway design. It must be kept in mind when writing the justification that design exceptions arise because it is impractical or impossible to reasonably meet a specific design criteria. If the criteria can be reasonably met, then the item in question is built to the criteria. The justification may include appropriate economic analysis, discussion of applicable accident location and type or discussion of avoidance of Section 4(f) or Section 6(f) lands. The justification supports the concept that maximum service and safety benefits were realized for the cost invested. Engineering judgment is used when balancing the economic and engineering reasons for the justification. A design exception is based on sound engineering judgment rather than an attempt to save cost.
If the design exception request involves any features that are safety related, then sufficient accident data and history is attached to the request to support the reasons for justification. A summary report of the accident information is acceptable if the volume of the data is excessive. The discussion justifying the feature will also include a comparison of the accident rate for the project or specific location to the statewide accident rate for similar routes. Examples of safety related features are included in, but not limited to, the following list: lane width, shoulder width, bridge width, bridge approach rail, horizontal alignment, vertical alignment, grade, horizontal clearance, vertical clearance, guardrail, etc. Any other items that may be perceived as a safety concern will also follow these requirements.
A transmittal letter that describes the nature of the exceptions that are requested will accompany each design exception request. This letter will also include a brief description of the purpose and need of the project and the improvement goals that it is intended to accomplish. This information is required since the context of the project often helps in deciding if the exception is to be approved.
All exception requests for "non-exempt" projects (interstate in excess of $1 million, major bridge, ITS, and other special projects) are submitted to the Design Division for approval, where the design liaison engineer reviews and forwards them to the State Design Engineer. After approval by the State Design Engineer (State Traffic Engineer for access management items or the State Bridge Engineer for bridge items), the design liaison engineer will provide the information to the FHWA for their approval. Once approved by the FHWA the design liaison engineer will provide a copy of the signed exception to the district and/or other affected divisions at the Central Office.
Exception requests for "exempt" projects (all other projects) do not require direct federal oversight and therefore will not require FHWA approval. For these projects where a design exception is required the district engineer has final approval authority. However, the district must submit a copy of the approved design exception to the Design Division.
Changes in project scope or design criteria can result in changes to design exceptions that have previously been considered. There may also be additional features that were not included on an earlier exception request that now requires approval. In these cases, an amended Design Exception Information Form must be completed and approved (as described above). The amended form should include all exceptions previously approved in addition to the new features. The transmittal letter will include sufficient information to indicate the items that have received prior design exception approval.
The Design Division maintains the design exceptions in a permanent project file. A copy of the form is also kept in the district file and any other affected Central Office Divisions.