to areas where approval of design exceptions is anticipated for the project to be successful. Design Exceptions will be identified by the designer and the supporting documentation will be submitted to GDOT Office of Design Policy and Support for approval. For design exceptions to be approved they must demonstrate that the deficient condition is not creating an unsafe condition and an analysis of what will be required to correct the deficiency. In some instances, the increased cost of correcting the deficiency as part of the Stitch project would be considerably lower than trying to correct the issue with a future project once the Stitch is in place. For example, the design proposes to construct new bents to support the cap structure, and proposes construction methods that could offset the outer walls of the Downtown Connector. Offsetting the retaining walls & bents could accommodate space for full width shoulders. Accommodating this additional space would increase construction costs due to longer bridge span lengths, and would expand the construction envelope, incurring additional right-of-way costs for the larger footprint. However, this cost may be nominal when compared to the overall construction cost of the project and when compared to what would be required for a future project to accommodate full lane and shoulder widths. Once the Stitch is constructed, accommodating wider shoulders and lanes would likely require demolishing the entire cap structure to widen the roadway below. As part of the design exception development, a cost estimate of a configuration that would accommodate the design standard would be required. The implementation plan for the Stitch does not include replacing the existing roadway overpass bridges. Replacing these bridges would add significant costs to the project for construction and staging of traffic. It is anticipated that design exceptions for retaining these structures are more likely to be approved, but considerations in the design process should be given to how new cap structures interface with the existing bridge structures so as not to complicate bridge maintenance or future replacement of these bridges without impacting the Stitch structures. VERTICAL CLEARANCES The previous infrastructure analysis for the Stitch performed a vertical clearance screening for the project corridor. This evaluation utilized the Georgia Department of Transportation (GDOT) guidance of allowing a minimum of 17.5 feet of vertical clearances to structures that cannot easily be reconstructed, which will be applicable to the Stitch bridge structures. The screening noted that some locations did not meet the minimum clearance requirements, however these locations were at existing overpasses. The screening concluded that the proposed bridge cap structures of the Stitch will be able to meet recommended clearance requirements. The analysis assumed a structure depth of 7.5 feet for the bridge cap structures, which is a reasonable depth for the proposed bridge structure but does not account for clearance needs for additional items which will also need to be positioned over the
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