Other Agencies with Actions or Authorizations:

California

Description:

The Interstate 405 (I-405) Improvement Project from State Route 55 (SR-55) to Interstate 5 (I-5 (proposed project) is being undertaken by the Orange County Transportation Authority (OCTA) in coordination with the California Department of Transportation (Caltrans) District 12 and the Federal Highway Administration (FHWA). The proposed project comprises one No Build Alternative and two build alternatives, both of which involve widening of the I-405 between I-5 (Postmile 0.2) and SR-55 (Postmile 8.7) in Orange County.

Purpose

The purpose of the proposed project is to address existing and future traffic demand and provide future mobility while minimizing environmental and economic impacts. The proposed project would address congestion and enhance freeway operations within the project limits along I-405 as follows:

• Add mainline capacity to reduce corridor congestion and improve mobility throughout.
• Improve the capacity of the ramps within the project limits along the I-405 corridor.
• Improve freeway operations including weaving, merging and diverging, and Intelligent Transportation System (ITS) elements within the project limits along the I-405 corridor.
• Enhance safety.

Need

Currently, this portion of the I-405 corridor within the project limits is experiencing congestion and long traffic delays during morning and evening peak hours due to demand exceeding capacity, resulting from local, regional, and interregional traffic demand. In addition, forecasted local and regional traffic demand is expected to increase, resulting in traffic volumes along the corridor ranging from 280,000 to 355,000 vehicles per day by the year 2050. Improvements are needed within the proposed project limits due to the following conditions:

• High level of congestion during weekdays, especially during peak periods due to the insufficient existing mainline capacity.
• Congestion at interchange on-ramps and off-ramps due to high demand, limited storage capacity, and operational deficiencies.
• Inadequate ITS infrastructure along I-405 and at interchanges.

This corridor has current and future operational deficiencies, including existing geometric deficiencies on the GP and High Occupancy Vehicle (HOV) lanes. Further, the GP and HOV lanes are operating under degraded and congested conditions. This corridor also experiences congestion at the ramps and freeway-to-freeway interchanges due to high traffic volumes and merging, and diverging issues.