Scott Avenue Bridge Rehabilitation Scott Avenue over Des Moines River

Scott Avenue Bridge Rehabilitation Scott Avenue over Des Moines River

Previous UDR Meetings: - January 24, 2017: General overview of TIGER Grant Projects - May 16, 2017: Preliminary review of all 4 bridge projects (Scott Ave., SW 1 st., Court Ave., Locust St. General comments received from May 16 th UDR Board meeting: - In general, didn t like the sidewalk railing proposed (galvanized round tube w/ vertical spickets). New rail should be more rectilinear design. - Would like to consider the existing aluminum railing be re-used along the sidewalk. - Look at original photos of bridge to take design cues for new railing - Railing(s) and MidAm LED street lighting should be black in color. - Work with Parks to provide more defined bike lane on west side. Responses to comments received: - Replacement street lights will be black poles/fixtures (LED) provided by MidAmerican Electric. - Original railing on the bridge was an ornamental balustrade railing, which was removed in 1981 when the bridge was widened. Replacing with ornamental balustrade railing is not in original scope/budget with this rehabilitation. - The City is currently working on a Transportation Master Plan and Connect Downtown that will determine lane configuration and bike lanes. Project will respond to those efforts if they are in place prior to striping, otherwise existing configuration will be replaced. - For the railing, several options were looked at. See further discussion.

Existing concrete intermediate posts are to remain. Two Main Options with Sidewalk Railing Re-use existing aluminum railing Replace railing with new railing Additional consideration is a handrail needs to be installed on the bridge barrier rail to meet current standard height requirements.

Option 1 Re-use existing aluminum railing: --Not being recommended New aluminum handrail. ~$175,000 Re-use existing aluminum rail. ~$50,000 Challenges: - Sidewalk rail posts are cored/grouted into sidewalk which causes constructability issues: To perform sidewalk repairs and concrete overlay, rail posts will need to be cut off at the sidewalk elevation to avoid damage. To re-mount the existing railing, new aluminum base plates will need to be fabricated and welded to existing railing to be mounted to sidewalk surface. - Aluminum railing would contrast against new black LED light pole fixtures. - Higher costs, total estimated at $225,000. - Aluminum is an expensive material and railing (including handrail) is more difficult and costly to repair. Advantages: - Keeps rectilinear design and preserves existing feel of the bridge. - Rail type would be same experience for anglers fishing off of bridge.

Option 2 Install new railing: - Engineering Dept. recommendation. Black tubular ornamental railing, pre-manufactured. ~$50,000 Black tubular ornamental railing, pre-manufactured. ~$75,000 Challenges: - Would be a different look than existing. - Possibly not as durable as aluminum, from a corrosion standpoint. Advantages: - Keeps rectilinear design. - Pre-manufactured rail is galvanized steel, and receives factory powder coating, generally with a 15 yr warranty. - Black color will match new black street LED light poles/fixtures. - Pre-manufactured rail could have 2 top rails, or just 1 top rail, to keep similar to existing geometry (more options). - Panel construction allows for easy replacement of panels, if damaged. - Costs are more favorable to other option, currently estimated at $125,000. - No known problems with similar rails on other bridges (Fleur Dr., 6 th Avenue, Grand Ave. @ Walnut Cr).

Handrail members would be altered to square tube to blend better with sidewalk railing. Example photo: Location Fleur Drive, just south of Gray s Lake Rail system is available as a single top rail, or as double top rail as shown in the picture.

Road View (looking Northeast) 49-0 roadway with one 8-0 sidewalk on bridge Painted for one lane (each direction) and parking on downstream side of bridge One bike lane across bridge Roadway striping can be adjusted if changes needed (Transportation Master Plan) Roadway lighting to be upgraded to LED lighting (black fixtures and poles)