In March the Menlo Park Transportation Commission got a preview of how the agency might accomplish those goals. The six designs under consideration — four using variations of a partial cloverleaf, and two using a diamond configuration — range in cost from $38.2 million to $54.9 million for construction costs and right-of-way acquisitions.
A half cloverleaf design, labeled "1B" in the staff report with an estimated price tag of $42.5 million, appears to be the leading contender after consultants reviewed the designs. The city of East Palo Alto has also expressed its support for that configuration.
One key request from Menlo Park is to evaluate the feasibility of adding a median bike lane along Willow Road, through the interchange. The staff report states that a median lane presents some safety issues, as drivers aren't used to it and it exposes bicyclists to traffic on both sides at intersections.
The design team concluded that the option wasn't viable. "It works when you have a full cloverleaf because as you go through the entire overcrossing you have no intersections. But when you have intersections there, the whole thing starts to break down," said Public Works Director Chip Taylor.
Mr. Taylor said that design 1B, in addition to minimizing the right-of-way impact on property owners near the interchange, also incorporates signalized on-ramps and "squared off intersections" so that drivers must slow down and make a right turn to enter the freeway, creating a "better experience for bicyclists" traveling alongside other vehicles.
The draft environmental analysis for the project should come before the City Council and public starting in April, with the final report expected to be done sometime this fall.
Caltrans plans construction to start in 2016 and finish within two years.The project first needs to secure full funding, however, before proceeding.
Mr. Taylor said the agency hopes to leave as much of the current infrastructure intact throughout construction to minimize traffic impacts, but it's too early to outline how exactly that will occur. "They still have to select the alternative and work through the environmental process first before getting to those details."
Go to tinyurl.com/bz6bofz to review the staff report and proposed interchange configurations.