Revitalization Commission Agenda and Packet 2013 12 09

Home Browse Search

C ltI". Louisville COLORADO ^ SINCE 1878 Department of Planning and Building Safety 749 Main Street • Louisville CO 80027 • 303.335.4592 • www.louisvi11eCO.gov Memorandum Date: December 5, 2013 To: Aaron DeJong From: Troy Russ, AICP Subject: South Street Gateway - Project Update The City is continues to work with Atkins to design the South Street Gateway. The project's design is approximately 60% complete. The City received BNSF's initial 60% design comments in October. In their comments, BNSF refined and clarified their guidelines for maintenance access and security for the rail bridge. In short, BNSF wants specific minimum clearances between the structural components of the bridge and the City decorative screen wall. The Atkin's design response to BNSF's initial 60% comments narrowed the public opening of the underpass from 30' to an 22'. Subsequently, our design engineers followed up with BNSF in November and were able to extend the opening to 25'. The issue is the current bridge design has a maximized the capabilities of a single span — rolled beam structure. Expanding the opening to continue with a 30' opening would require a three span caisson structure, a new design. According to Atkins, a new three span caisson structure would double the construction cost over a single span rolled beam structure. Additionally, the new structure would require a structural beam approximately 1-foot thicker than currently designed. The additional thickness to the beam would reduce the floor to ceiling clearance from 9 feet to 8 feet. That difference could be accommodated by digging deeper into the earth. However, that would further increase the costs an additional $200k to $400k (above the doubling of the structure's costs). A change in design to accommodate a 30' opening and 9' clearance could likely exceed $5.5 million in costs. As a result, the design team is proceeding with the 90% design package with a 25' opening and 9'depth. Staff anticipates final approval from BNSF in February / March and a PUC hearing in April/May.