The Stitch Master Plan Appendices 1&2

implemented. Options 2 and 3 will retain the existing walls which will “lock-in” the substandard outside shoulder condition. Given the capital expenditure that will be necessary to construct the Stitch and how difficult it will become to address the shoulder deficiencies after construction, an opportunity to accommodate full width shoulder as part of the construction should not be discounted. GDOT and FHWA may be reluctant to approve design exceptions for a project that will effectively prevent the deficiency from ever being addressed in the future. Approval of design exceptions for the existing deficient shoulders present under the existing overpass bridges is more justifiable, as correcting the deficient condition would require reconstruction of these bridges. However, approval of a design exception for the shoulders not under existing bridge will be harder to justify in a design exception if a viable option for increasing the shoulder widths is a consideration without incurring significant additional costs to the Stitch. The alternatives which retain the existing walls also will present challenges in constructing emergency egress locations and accommodating the required lighting and ventilation equipment. The abutment construction under option 1 affords the opportunity to offset the proposed abutments as needed to incorporate additional equipment and emergency egress access. UTILITIES The presence of utilities along and under the Downtown Connector will be a major coordination component of the Stitch design. Utilities are known to be running adjacent and under the Downtown Connector. Excavation and construction of the cap structure bents and abutments will impact existing utilities. Determining how best to minimize and avoid impacts where possible will be key to the success of the project. Two major utility constraints identified to date are the City of Atlanta combined sanitary and storm sewer that runs adjacent to and under the Downtown Connector between the Piedmont Avenue/Baker Street bridge and the Courtland Street/Ralph McGill Boulevard bridge and the Georgia Power utility tunnel that runs under the Interstate just south of the Courtland Street/Ralph McGill Boulevard bridge. The City of Atlanta combined sewer system will present a significant challenge to the construction of new abutments behind the existing walls along the outside of the Downtown Connector, as the sewer system runs just behind the existing walls on both sides of the Interstate. The proposed plan to offset the abutment foundations behind the existing walls may come into direct conflict with the sewer lines. Accommodating additional space for emergency egress may also create conflicts as additional space to locate these egress points will push the construction footprint out and into conflict with the sewer lines. More detailed information on the location of the City of Atlanta combined sewer system will be needed to mitigate impacts.

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