City of Half Moon Bay Recommends Two-Stage Replacement Plan for Main Street Bridge

The fate of Half Moon Bay’s 110-year-old Main Street bridge may still be undecided but city officials are getting that much closer to making a final decision possibly by mid-September.

Last week, city officials posted a report analyzing a variety of options for fixing the bridge and ultimately recommending a two-stage replacement plan that would keep traffic open in both directions during most of the construction.

The council is scheduled to review the design options and could make a final decision on Sept. 17.

During its service life of over 100 years, the Half Moon Bay Main Street Bridge over Pilarcitos Creek has developed cracks along critical structural elements, threatening its stability during a significant earthquake or other such event. The most recent Caltrans inspection of the bridge in 2011 resulted in a sufficiency rating of 24 out of 100 and designated the bridge as “structurally deficient.”  

In 2010, the City asked its general engineering consultants, CSG Consultants, Inc., to analyze the bridge’s condition and recommend any necessary corrective action. As part of its analysis, CSG analyzed a number of options, including the following:

Option 1: Repair and rehabilitate existing structure

Option 2: One stage replacement

Option 3: Two-stage replacement

After an extensive competitive process including community input, the City retained URS Corporation, one of the largest firms offering engineering design services for public and private projects, for $1.2 million to further analyze the bridge’s condition and options for needed corrective action, and to provide professional services for design, environmental and cultural studies and assist with permits for the selected option.

The City conducted public meetings on the Main Street Bridge Project on December 19, 2012, February 6, 2013, February 13, 2013 and April 9, 2013 to provide project information and seek public input.

At the April meeting, after receiving staff’s report and extensive additional public comments and deliberation, the Council selected the following, in descending order of priority, as the criteria upon which to select the preferred option:

1.            Prevent catastrophic bridge failure to protect public health and safety.

2.            Construct project in manner that maintains at least one lane of traffic at most times during construction.

3.            Minimize construction impacts/disruptions (noise/access/staging) to those closest to the bridge.

4.            Minimize fiscal impact to the City and maximize use of grant funds.

5.            Least environmental impact and greatest probability of clearing regulatory hurdles.

Based on the criteria above, the city attorney, staff and consultants recommend Option 3, a two-stage replacement plan estimated to cost $840,000 (approximately $120,000 more than the least expensive option with an estimated net cost of $720,000) that would take the dry seasons of two years to fully complete, as the best proposal. 

While Option 3 is not the least impactful in terms of construction time, staging or noise impacts, nor is it the least expensive, based on an evaluation by the City’s project team, Option 3 received the highest overall score and was determined to have fully met the Council’s criteria with respect to protecting public health and safety, maintaining at least one lane of traffic at most times, and minimizing environmental impacts/regulatory hurdles.

What do you think of Option 3 for the bridge rehabilitation/replacement project? Tell us in the comments.