CITY OF LARKSPUR BON AIR BRIDGE REPLACEMENT PROJECT PRESENTED BY Mary Grace Houlihan Larkspur Public Works Director DATE August 20, 2014
Bon Air Bridge
Why Replace the Bridge? • The Bridge is structural deficient • Improve access and safety for pedestrians and bicyclists – Multi-use paths, – dedicated Bike Lanes – Barrier separation
What is the Project? • Replacement of Bon Air Bridge with a wider, seismically safe new bridge – Within sensitive environmental context • Barrier-protected multi-use path • Traffic and lighting improvements – Downcast nighttime lighting, meeting International Dark Sky standards • Organic, natural design
Project History • 1958 – Original Bridge was built • 1970 - Major foundation repair due to damage from channel dredging • 1994 - walkway widening and a seismic retrofit • 2000 – Cal-trans inspections showed crumbling at several support locations. Further inspections in 2003 revealed severe deterioration of concrete, including visible cracks on some supports, and poor deck conditions. • 2002 - the City applied for and received funding through the Highway Bridge Replacement Grant to replace the Bon Air Bridge. • 2012 - temporary supports were added to stabilize the structure. A new replacement bridge was determined to be the most cost-effective measure to ensure continued unrestricted access for all modes of travel over the bridge.
Project History • The final design for the bridge is the result of an extensive public outreach process and in 2008 the City Council approved the conceptual design for the new bridge.
Project History • 2012 - Both California Environmental Quality Act and National Environmental Protection Act certifications were completed for the project • Permits have been obtained through RWQCB, US Fish & Wildlife, Army Corps of Engineers and California Fish and Wildlife. BCDC is nearing completion and is anticipated to be in place in the next couple of months. • Design has been completed • Utility relocations has been initiated by Comcast & MMWD • Contractor prequalification has been initiated
Status and Schedule • PGE to initiated temporary relocation in Fall 2014 • Final Construction Authorization is anticipated by January 2015 • Project Bid in early 2015 • Bridge Construction slated to begin in Spring 2015 and anticipated to end Summer 2018
Public Outreach • Council Presentation Update – Tonight • Neighborhood and Business community meetings to be scheduled from Sept – Dec, 2014 • Project Website to be opened in September 2014. larkspurbridges.com • Public Outreach boards to be placed on main trails and at City Hall, Recreation, Library & Piper Park
Constraints on Construction Preservation and monitoring of fourteen regulated species: • California Clapper Rail and Black Rail • Central California Coast Steelhead and Coho Salmon • North American Green Sturgeon • Western Pond Turtle • Northern Harrier • White-tailed Kite • Short-eared Owl • San Francisco Common Yellowthroat • Samuels (San Pablo) Song Sparrow • Western Red Bat and Pallid Bat • Salt Marsh Harvest Mouse Photo: Flickr/Len Blumin
Constraints (Continued) • In Water Work limited based on Clapper Survey and Fish Migration • Accessibility for vehicles, pedestrians, bicycles, and water traffic • Maintenance and installation of utility services • Maintenance of business access • Emergency access to hospital • Safe and functional work site
Schedule of Construction • Spring 2015 Anticipated start; shift traffic, close bike lane & upstream walkway • Summer 2015/Spring 2016 Install temporary trestles, demolish upstream portion of existing bridge, abutment construction, utility & right-of- way work north and south of the bridge • Fall 2016/Winter 2017 Construct upstream side of new bridge
Schedule of Construction (Continued) • February 2017 Move traffic to new upstream bridge (no bike lanes, one extra wide multi- use path) • July 2017/January 2019 Demolish remaining bridge, construct new downstream half • January 2019 Open to full traffic • Spring/Summer 2019 Complete restoration and removal of trestles Photo: Roger Tabor/USFWS
Construction Impacts • Approximately 3-4 years of construction from Spring 2015 to Summer 2018, 5-6 days per week – Monday – Friday 7:30AM to 6:00PM, Saturday 8:30AM to 6:00PM • Periodic night work • Periodic pedestrian and bike traffic control for safety and utility service requirements • Periodic one-way traffic on bridge (10- to 15-minute delays) • Periodic waterway traffic control • Anticipated full closures: – 2 weeks for delivery and installation of precast girders – 1 week for closure pour between upstream and downstream halves of new bridge
Public Info Updates during construction • Website • E-mail notifications • 24 hour hotline • Notice boards on key trails, Piper Park & City buildings • Contact signs at entrances to residential communities throughout the City • E-mail notices through schools and PD contact lists • Message Boards at either end of the bridge Trails & Neighborhoods
Environmental Mitigation APE = Area of Potential Effect
Bon Air Bridge Replacement APE = Area of Potential Effect
Tidal Marsh Restoration and Dog Park Relocation at Piper Park
Access and Dock Improvements at Bon Air Landing Park ADA Pathway
Access and Dock Improvements at Marin Rowing Club ADA Pathway
Drainage Improvements on Magnolia
Questions?
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