10E Consent - Laserfiche WebLink

Home

File Number: 22-428 Studies of the subject intersection indicate that a roundabout would provide the most improvement to traffic flow and traffic calming compared to other alternatives, such as a traffic signal. The conceptual design for the roundabout was completed in 2009, but due to a lack of funding, the City did not enter into a design contract with BKF Engineers for the development of construction-ready plans, specifications, and estimates (PS&E) for the roundabout until 2016. The original 2009 roundabout design concept required bicyclists to either ride in the same lane as motor vehicles or to share the sidewalk with pedestrians. Based on comments received from the City Council Facilities and Transportation Committee, and public meetings, most individuals expressed a preference for a dedicated lane within the roundabout for bicyclists, so protected bike lanes were added to the conceptual design, which increased the project’s footprint. The project includes the construction of a roundabout at the intersection of MacArthur Boulevard/Foothill Boulevard and Superior Avenue that would improve safety for all users. The project also includes installation of protected bike lanes, as well as pedestrian crosswalks. The City has been working with Caltrans to decertify the additional right-of-way needed for the project, which has taken more time and effort than originally anticipated for NEPA environmental clearance and approval of PS&E documents. A retaining wall approximately 220 feet long with a maximum retained height of 3 feet will be constructed as part of the subject project near the bottom of the existing Interstate 580 freeway embankment. The City and its civil design consultant, BKF Engineers, met with Caltrans in April 2022 and learned that the retaining wall will require an informal structural type selection process for Caltrans to approve the wall’s design. As a result, additional field work for topographic surveying, coring of the existing embankment, and sampling and testing of the existing soil is necessary. Structural design of the retaining wall is also necessary, since a standard Caltrans retaining wall cannot be utilized due to the peak ground acceleration at the project site. Peak ground acceleration is the maximum ground acceleration that is expected to occur at a particular location in the event of an earthquake. Analysis The cost of $233,559 for Amendment No. 5 with BKF Engineers represents the upper limit of what the additional field work and design costs could be. City staff is working with Caltrans and BKF Engineers to assess whether historical soil boring information from past State projects can be utilized to eliminate the need for new soil borings. It may also be possible that the record soil boring information will support the use of a standard Caltrans retaining wall, which would significantly reduce the amount of additional design work. Alternatives to constructing a roundabout at this location were evaluated and rejected. A common solution, installation of a traffic signal, is not feasible because the high volume of traffic along MacArthur Boulevard would queue back onto the Interstate 580 offramp when the cross traffic has the right of way. Another option would be to revert to the original design concept for the roundabout, which did not involve acquiring right-of-way from Caltrans or right-of-way from adjacent property at 650 Page 2 City of San Leandro Printed on 7/13/2022