The Design Division of the Roads Department prepares plans and contract specifications for construction of County road projects by independent construction contractors. Contracts are issued through a public low bid process to appropriately licensed and experienced contractors. Construction contracts are administered and inspected by the Division. State of California (Caltrans) Standard Specifications and Plans serve as the primary guidelines for design and construction.

Most often others initiate proposed projects and their priorities. Design's efforts begin after the need for a project and the budgeted funds are determined. Priorities for maintenance or reconstruction of existing roads are determined by the Maintenance Division based upon need and cost effectiveness. Needs for traffic safety or capacity improvements are initiated by the Traffic Engineering Division based upon their monitoring and study of the roadways. The Development Review Division coordinates regional growth issues with other agencies and analyzes future needs for new roads or road widening. The Roads Department goes to great effort to combine the variety of needs, input from all the Divisions, and all available funding sources to develop and maintain the best possible County maintained road system.

Much of the funding available for transportation purposes is provided from state and federal sources that are specifically categorized for certain types of work. For example, Congestion Mitigation Air Quality (CMAQ) funds may generally be used only for transit bus services, congestion relief such as traffic signals/channelization, or other air quality projects. CMAQ funds may not be used for road maintenance or reconstruction.

Projects currently in the design or construction phases and their status may be reviewed here.