Inter-Departmental Correspondence

Department of Public Works



January 21, 2011


February 8, 2011







Honorable Board of Supervisors


James C. Porter, Director of Public Works


Truck Traffic on Highway 84



Adopt a Resolution authorizing the Director of Public Works to perform truck restriction studies on Highway 84.



Residents from the South Skyline Association in unincorporated San Mateo County have approached Caltrans and San Mateo County to request truck traffic restrictions, for trucks exceeding 30 feet in length (from king pin to real axle), on the segment of Highway 84 between Portola Road and Skyline Boulevard.


Highway 84 is under the jurisdiction of Caltrans. The communities directly adjacent to the road segment in question are either the Town of Woodside or the County of San Mateo, depending on location. Caltrans has indicated that they cannot implement additional vehicular restrictions to legal sized vehicles, absent legislative action or the submittal of a formal request from a local agency for Caltrans’ consideration.


This matter has been presented to the Finance and Operations Committee and said Committee has directed this Department to present the full Board with the recommendations made herein.



South Skyline Association residents cited several truck incidents and voiced concern over road safety on Highway 84. They requested that trucks exceeding 30 feet in length (from king pin to rear axle) be required to utilize a pilot car or be prohibited from travel on Highway 84 between Portola Road and Skyline Boulevard.


Caltrans staff indicated that a pilot car requirement was not an option and that legislative actions to restrict vehicular movement is a time consuming process that may not be successful. Caltrans recommended that a local agency action, including the performance of traffic studies, a community review and comment period, and the submission of a draft truck restriction ordinance to Caltrans would be the most effective means of restricting larger trucks on Highway 84. However, it is possible that a local agency would invest in the requisite studies and have Caltrans not accept its recommendations relating to truck traffic restrictions.


The Department believes that a truck traffic study, for the purposes of restricting truck traffic on Highway 84, would warrant a parallel study along Kings Mountain Road, as drivers have an option above the Town of Woodside to access Skyline Boulevard either through Highway 84 or Kings Mountain Road. Kings Mountain Road, which is under Woodside and County jurisdiction, is generally much narrower and windier than the segment of Highway 84 between Portola Road and Skyline Boulevard.


In addition, it is noted that legal sized moving trucks, delivery trucks, and trucks hauling construction equipment and materials destined for properties along the route could not be banned from using Highway 84, regardless of the restrictions implemented. If a truck traffic restriction ordinance or resolution were to be accepted by Caltrans, the local agency would be required to implement the road restrictions through the installation of appropriate signage.


County Counsel has reviewed and approved the Resolution as to form.


Approval of these actions contributes to the Shared Vision 2025 outcome of a Collaborative Community by implementing regional truck traffic restrictions in an effort to reduce risks associated with the usage of Highway 84 by large trucks.



It is estimated that traffic studies to assess the viability of large truck restrictions on Highway 84 and on Kings Mountain Road would cost $50,000.00. Staff time costs associated with managing these studies, holding public meetings, processing requests to Caltrans and installing appropriate street signing are estimated at $15,000.00.


By law, Road Funds cannot be used for the performance of work, including studies, on roads outside of the County’s maintenance jurisdiction. Funds will be transferred from Non-departmental Services to reimburse the Department of Public Works for expenditures related to truck restriction studies on Highway 84.


County staff is working with the Town of Woodside and with Caltrans to determine whether there is any opportunity for the Town of Woodside and for Caltrans to share in these costs.