Overview

OCTA administers the Master Plan of Arterial Highways (MPAH), including the review and approval of amendments requested by local agencies. The MPAH is a countywide transportation plan for Orange County, designed to manage and improve the arterial highway network. Established in 1956, the MPAH was created to complement the county’s developing freeway system and has evolved into a critical element of Orange County’s long-range transportation policy.

Over the years, the MPAH has played a crucial role in shaping the county’s transportation infrastructure, ensuring a coordinated effort between OCTA and the cities within Orange County. The primary goal of the MPAH is to outline a regional arterial highway system that supports existing and future land uses, ensuring that roads are designed to accommodate projected traffic volumes. It aims to provide a circulation system that complements the county’s freeway network, focusing on the efficient movement of people and goods.

MPAH Zoomable Map

Download PDF Map (15MB)     Download MPAH Guidelines

Annual Traffic Volume Maps

Average daily traffic counts on arterial roadways are collected from each of the 34 cities and the county on an annual basis to create the Traffic Flow Map. OCTA reviews the traffic volumes and adjusts the data, as necessary, to reflect weekday traffic for the year of the published map. Not all cities update their counts on an annual basis. For these cities, previously provided counts are adjusted based on traffic growth in the surrounding area. Annual average daily freeway volumes are collected by CalTrans and adjusted for the map to reflect a 5-Day (weekday) count. The map is used for transportation planning and to compare and validate the results of travel demand forecasting models.