CALIFORNIA STATE ROUTE 79
FREEWAY CONVERSION PROJECT
ALTERNATIVE #3 - HYBRID
California Avenue (North)
OVERVIEW
Our third alternative is the Hybrid Interchange. This consists of Hook ramps for the Northbound ramps and a tight diamond for the Southbound ramps.
TRAFFIC ANALYSIS
The traffic team performed a traffic analysis for this alternative using Trafficware Synchro 10 to evaluate the number of approach lanes and level of service. Peak hour traffic volume data was obtained from Caltrans Traffic Counts Census, Riverside County Traffic Analysis Model (RIVTAM) and Southern California Association of Governments (SCAG) Model. The annual growth rate for traffic volumes for 2025 and 2045 were forecasted using Caltrans 2017 Transportation Concept Report. The hybrid design will have two intersections. For SB intersection, the 2025 AM/PM LOS is B/B and the 2045 AM/PM LOS is B/B. For NB intersection, the 2025 AM/PM LOS is B/B and the 2045 AM/PM LOS is B/B. These results satisfy the minimum LOS requirement of D as set forth by Caltrans standards.
GEOMETRIC FEASIBILITY
This alternative seeks to incorporate the near-perpendicular bridge of the hook ramp alternative to decrease the structures cost, along with diamond ramps on the Western side of the 79 to minimize ROW and environmental impact. However, this design does not meet drivers expectations as well as the others due to different types of ramps being implemented on each side of the bridge.
ENVIRONMENTAL IMPACT
The Hybrid Alternative near-perpendicular bridge along with a Hook Ramp design on the Northbound and a Tight Diamond design on the southbound allow for the least amount of right of way impacts. Partial and full acquisitions are required for some vacant and residential parcels. Due to the project site rolling terrain condition, the introduction to retaining walls were introduced. The proposed alternative requires utility relocation. Continuing, proper drainage will be implemented in the design and a Storm Water Pollution Prevention Plan as outline by the Riverside County Flood Control and Water Conservation District. Some potential permits or approvals required include air quality, 401 Permit, and 404 permits.
DETAILED DESIGN
The cross-section of California Ave. in the Hybrid alternative will have a 6' sidewalk, a 4’ bike lane in each direction to improve access for all users, a 4' external shoulder, two 12’ through lanes, and a 12' median. Bike lanes and sidewalks were included in our bridge design to promote active mobility and accessibility for all modes of transportation. The ramps of this alternative consist of an 8' external shoulder, one 12' lane with auxiliary to provide additional capacity on the intersections, and a 4' internal shoulder.
For our project study report, an Advance Planning Study (APS) was done to define the scope of structure work and develop a reasonable cost estimate for budget purposes. APS consists of a plan sheet for each structure with basic dimensions and minimal detailing including the vertical clearance, span length, and structure type. Each plan sheet contains the plan, elevation, typical section view, and cost estimate of the structure. All these structures will be constructed out of precast concrete. The Bridge Design Aids were used for the design of the new bridges. Please refer to the Geometric Approval Drawing and Advanced Planned Study under the Deliverables tab for geometric details of this alternative.
VIABILITY
The Hybrid Alternative was carefully revised and evaluated based on multiple factors including: Alternative Scoping, Traffic Analysis, and Geometric Design. It was considered as one of the three viable alternatives as it satisfied all the categories mentioned above. It also passed geometric feasibility, and impact evaluation steps and was considered viable for detailed design. All documents and deliverables pertaining to this design can be found under the Project Deliverables Tab.
