I-5 / Oso Parkway Interchange Project
- SCH Number
- Public Agency
- California Department of Transportation, District 12
- Document Title
- I-5 / Oso Parkway Interchange Project
- Document Type
- NOE - Notice of Exemption
- Document Description
- The project proposes improvements to the I-5/Oso Parkway interchange (PM 15.156). The improvements outlined in the Project Study Report (PSR) for the Project include: (1) sight distance improvements to the northbound ramps, (2) operational improvements at the southbound off-ramp and SCRRA overcrossing, and (3) the construction of a southbound auxiliary lane in advance of the southbound off-ramp at the Oso Parkway Interchange (Caltrans, 2001). Interchange Improvements: The improvements propose to increase vehicle safety at the southbound freeway mainline diverge area at the interchange, as well as reduce vehicle queuing at the off-ramps, and reduce the forecast unsatisfactory LOS F operations at the interchange to LOS D or better. Arterial widening, including widening of the Oso Parkway overhead structure also is proposed. The specific project improvements include the following activities: Northbound Ramps: - Realign the eastbound Oso Parkway to the northbound I-5 loop on-ramp instead of building a retaining wall as identified in the PSR. This alternative provides the benefit of not requiring construction easements from the Fairfield Inn property; it provides greater sight distance; and it will not require removing the existing retaining wall to build a new higher wall. Improve sight distance on the direct on-ramp from westbound Oso Parkway to northbound I-5 by realigning the ramp lane and adding a standard shoulder. Provide additional roadway width at both on-ramps to provide for a two-lane on-ramp in the future (3.6-meter-wide lanes). Widen the existing northbound off-ramp from two to three lanes with standard shoulders. This will require construction of a shared left- and right-turn 213-meter (700-foot) storage lane in advance of the intersection with Oso Parkway. This will provide for three lanes at the approach to Oso Parkway from the off-ramp. Southbound Ramps: - Construct a 400-meter (1,310-foot) auxiliary lane in advance of the off-ramp in accordance with HDM Section 504.3 (6). Widen the southbound off-ramp to Oso Parkway from one 3.6-meter (12-foot) lane to two 3.6-meter (12-foot) lanes at the gore point. - Widen the ramp lanes at the intersection of the I-5 off-ramp with Oso Parkway from three 3.6-meter lanes to four 3.6-meter lanes. The geometrics will include two left-turn lanes and two right-turn lanes. The right lanes will improve right-turn movements for trucks to westbound Oso Parkway by providing a larger curb return radius. This will require a Type 1 retaining wall along the edge of shoulder. The length of the two right-turn storage lanes at the off-ramp will be 244 meters (800 feet) for the inside right-turn lane, and 91 meters (300 feet) for the outside right-turn lane. Convert the existing HOV bypass lane on the southbound loop on-ramp to a mixed-flow metered lane. Oso Parkway Overhead - Bridge No. 55C-56 - Widen both sides of the bridge structure and provide the following westbound geometrics: two 3.6-meter (12-foot) left-turn lanes, three 3.6-meter through lanes, one 3.6-meter right-turn lane, and 2.4-meter (8 foot) shoulders in both directions between I-5 and Cabot Road. Cabot Road / Oso Parkway Intersection - Install an overlapping northbound right-turn (with westbound left turns) signal phase at the intersection. Extend the westbound right-turn storage lane to the southbound off-ramp consistent with the widening of the Oso Parkway Overhead.
- Contact Information
Department of Transportation, District 12
3337 Michelson Drive, Suite 380
Irvine, CA 92612
Phone : (949) 724-2243
- Laguna Hills Mission Viejo
Notice of Exemption
- Exempt Status
- Categorical Exemption
- Type, Section or Code
- Section 15301
- Reasons for Exemption
- The project involves minor operational and safety improvements to an existing facility (interchange) within the existing right-of-way at I-5/Oso Parkway, Orange County. The project will not have a significant impact on the environment, impact hazardous sites, involve substantial controversy on environmental grounds, involve significant impacts on properties protected by Section 4(f) of the DOT Act or Section 106 of the National Historic Preservation Act, or damage a scenic resource within an officially designated state scenic highway. This project is included in a currently conforming plan and Transportation Improvement Program.
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