I-5 / Oso Parkway Interchange Project

I-5 / Oso Parkway Interchange Project

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.

Laguna Hills, Mission Viejo

Orange