COMMUNICATION URBAN DESIGN REVIEW BOARD CITY OF DES MOINES, IOWA MAY 16, 2017 MEETING Subject: Recommendation Prepared by: PRELIMINARY DESIGN REVIEW OF LOCUST STREET BRIDGE CONSTRUCTION & COURT AVENUE, SCOTT AVENUE, AND SW 1 ST STREET BRIDGE REHABILITATION X APPROVE DISAPPROVE NO ACTION OTHER ERIN OLSON-DOUGLAS, ECONOMIC DEVELOPMENT DIRECTOR, 283-4021 Attachment Listing: http://www.dmgov.org/government/boards/urbandesignreviewboard/pages/meetings.aspx Summary: The City is in the midst of a major $22 million downtown bridge overhaul project known as Bridges to Opportunity: Des Moines Community Connection, consisting of the reconstruction and replacement of several roadway and multi-use trail bridges crossing the Des Moines River. In July of 2016, the City received an $8 million TIGER transportation infrastructure grant, setting the design work in motion on multiple downtown bridge projects that will be reconstructed or rehabilitated over the next 5 years (project span from 2016 through 2021). This will include the reconstruction of the Locust Street Bridge, the historic renovation of the Court Avenue Bridge, and rehabilitations on the Scott Avenue and SW 1 st Street Multi-Use Pedestrian Trail bridges, all of which are also subject to State Historic Preservation Office (SHPO) review prior to final design. The Walnut Street Bridge will require future replacement or renovation, but is not a part of this project at this time. The scope of work proposed on each of the bridges within this project is below: Locust Street Bridge The existing bridge was originally constructed in 1909, and an engineering feasibility study has determined that the most economical solution is bridge replacement. The new bridge design will largely mimic the approved design of the Grand Avenue Bridge that is currently under construction, and will have an $8 million dollar project budget. There are slight variations from the Grand Avenue Bridge design including the width of travel lanes, parking lanes and sidewalks. The reconstructed bridge will feature two 12 wide travel lanes, two 9 wide parking lanes, and 12 wide sidewalks on each side of the bridge. The eastbound travel lane will incorporate bike lane sharrow pavement markings, as they currently exist. The vehicle and pedestrian barrier is combined into one element at the outer edges of the bridge, consisting of galvanized steel, which allows for a better view of the river for pedestrians that typical concrete barriers would. Overhead roadway lights will consist of the Mid-American standard found throughout downtown, which includes upgraded black light poles and LED light fixtures. Pedestrian lights will be integrated into the barrier to more directly illuminate the sidewalk and eliminate the need for additional overhead lighting. The exterior of the bridge entails painted metal panels with galvanized framing that is concealed from view, which creates a scalloped effect on the sides of the bridge. This design is derived from the input and direction previously received from the Grand Avenue Bridge Aesthetic Review Committee.
PAGE 2 SW 1 st Street Pedestrian Bridge The SW 1 st Street Multi-Use Trail Bridge was originally built in 1937 for vehicular traffic, and was known as the Riverside Drive Bridge. Repairs to the bridge were conducted in 1973, and the structure was converted to a trail bridge in 2006. To prolong the life of the bridge, additional structural repairs are needed at this time, which constitutes the majority of the scope of work on this $950,000 project. The existing raised planter beds are proposed to be removed from the structure, which have proven to be difficult to maintain. Additionally, the planter removal on the southern terminus of the bridge will make room for a planned B-Cycle bike rental kiosk to be installed. The existing bridge railing, decorative lighting and benches will remain in place. Court Avenue Bridge An estimated $7 million dollar restoration of the circa-1917 Court Avenue Bridge is proposed, that will prolong the life of the structure and keep the historic appearance intact. The bridge is listed on the National Register of Historic Places and is a vital part of the Civic Center Historic District. The work will remove and replace the bridge deck paving and sidewalks, repair abutments, pierces, spandrel walls, columns and floor beams, and will remove and replace the existing barrier rail. The replacement of the rail will either consist of a concrete replica of the current railing or will use alternate materials such as granite. The damaged limestone on the bridge fascia will be replaced with new limestone, and the existing limestone segments will be cleaned to remove growth and discoloration. The existing historic light fixtures are in inefficient, in poor repair, are no longer being manufactured, and have been replaced in other areas of Court Avenue where they were previously installed. Additional study is being conducted to determine an appropriate LED light fixture that will be historically compatible with the bridge, and study is also being conducted on how to provide architectural lighting of the historic railing and bridge fascia. The roadway and sidewalk dimensions as proposed will be similar to the existing roadway configuration. Scott Avenue Bridge The Scott Avenue Bridge was built in 1937 and was substantially rehabilitated in 1981. Current conditions of the bridge warrant significant repairs to extend the useful life of the bridge. The scope of work on this $3.9 million dollar bridge rehabilitation will largely be structural in nature, however, the bridge railing and lighting will be replaced, and the roadway and sidewalk will be repaired with a new concrete overlay. Scope of Review Board to make recommendation to City Council on: Design review of renovation /remodeling/new construction for City-owned or leased project. Design review for urban renewal project with specific development requirements. Whether a proposed urban renewal project qualifies for funding from tax increment. Whether the level of financial assistance funded from tax increment revenues proposed for a specific individual project are reasonable and appropriate. The selection of urban renewal sites for clearance or rehabilitation and problems relating to acquisition, clearance or rehabilitation of property, relocation of displaced persons and disposition of acquired property. Skywalk System Other
PAGE 3 Urban Design Review Board Action: The Board is asked to make its recommendation on the preliminary design of the projects at this meeting. A final design review of the project will be scheduled at a later date. Staff Recommendation: Staff recommends approval of the preliminary design review subject to the following comments: SW 1 st Street Multi-Use Bridge: 1. Evaluate the installation of the missing trail segment on the riverfront east of Principal Park as a component of this project. Court Avenue Bridge: 1. Consider construction of a bump out on the east end of the bridge to improve the pedestrian crossing conditions, similar to what s been installed on the west end of the bridge. 2. A more defined and historically compatible strategy for overhead and pedestrian lighting on the bridge should be provided. Scott Avenue Bridge: 1. Provision of decorative black light poles and LED lights installed on bridge, similar to the enhanced fixtures installed within the Downtown Overlay District. 2. Provision of an enhanced decorative railing, including the railing on the sidewalk separator. 3. Consideration of pedestrian lighting installed for the sidewalks. Background: The Grand Avenue Bridge was the first of several additional major downtown bridge reconstruction and rehabilitation efforts, and the bridge is currently under construction with an anticipated spring 2018 completion date. The previously convened Aesthetic Steering and Review Committee considered the visual appearance of the future downtown bridges relative to the Grand Avenue Bridge. While their recommendations were not solidly resolved, the general direction they provided was to replicate the aesthetics from the bridge deck down and have further conversation about the pedestrian experience for future bridges. Additionally, the Board previously reviewed and provided design approval to the Grand Avenue Bridge project on the August 4, 2015 meeting, and provided the following pertinent design comments that are relevant to the complimentary design of the Locust Street Bridge: More of a focus on the pedestrian experience, addition of bike lanes should be given to new bridge design Future bridge design should be kept open-ended to respond to the specific site conditions and evolving technologies. Do not feel an absolute need to match the bridges.
PAGE 4 Would not want to see four distinctly different bridges. Feel that the bridges should be similar, but respond to the individual design requirements at each location. All bridges within this project with the exception of the Locust Street Bridge have been deemed to be contributing structures within the Civic Center Historic District that encompasses much of the downtown riverfront
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