Roadway Design Modernization: Rancho Mission Viejo

Summary

Rancho Mission Viejo is a master-planned community in southern Orange County spanning 20,868 acres, established in 2005 on a former family ranch. Under the Southern Subregion Habitat Conservation Plan (SSHCP), 75% of the land is preserved as open space, with the remaining 25% designated for residential and commercial development. This project assumes the community is in its early stages of development, where a roadway network has yet to be established. As development progresses, traffic demand is projected to increase significantly, placing strain on Ortega Highway (SR-74) as the primary route through the area. Without a planned roadway network, continued growth will result in increased congestion, reduced levels of service, and safety concerns for future residents and commuters.

Anteater Transportation Engineering, sponsored by HDR, was tasked with designing a roadway network to provide an alternative route to Ortega Highway, improve internal traffic circulation, and support the community's long-term transportation needs. The project involved designing three connected segments totaling three-fifths of a mile: Cow Camp Road as a major arterial, Chiquita Canyon Drive as a secondary arterial, and Fauna Drive as a residential collector. These segments form a corridor linking higher-speed arterial traffic to residential areas while meeting local and statewide roadway design standards. The project was completed over two academic quarters in partnership with HDR engineers, who provided technical guidance and industry review throughout the design process.

Technical Approach/Methodology

The team applied a full roadway design workflow using industry-standard methods, references, and software tools across six core areas: traffic analysis, geometric design, pavement design, drainage design, plan set drafting, and cost analysis.
Traffic volumes for each roadway segment were established by interpolating between a 2019 historical traffic study and a 2045 projected study to determine Annual Average Daily Traffic (AADT) values for the year 2026. Vehicle classifications were assigned following Federal Highway Administration (FHWA) guidelines, and Equivalent Single Axle Loads (ESALs) were calculated using AASHTO methodology to quantify cumulative traffic loading over a 20-year design life.

Horizontal and vertical alignments were developed in Autodesk Civil 3D in compliance with the Caltrans Highway Design Manual and Orange County Public Works (OCPW) standard plans. Corridor models were built for each roadway classification, incorporating lane widths, curb and gutter assemblies, sidewalks, and intersection design with appropriate curb return radii. Cut and fill volumes were calculated by comparing existing and proposed terrain surfaces.

Pavement design was completed using the AASHTO 1993 nomograph method for both flexible pavement (Hot Mix Asphalt) and rigid pavement (Jointed Plain Concrete Pavement) alternatives. Design inputs included California Bearing Ratio (CBR), reliability, standard deviation, and Present Serviceability Index. A 50-year life cycle cost analysis was conducted to compare the long-term costs of both alternatives, accounting for maintenance treatments such as crack sealing, overlays, milling, and slab repair at scheduled intervals.
Drainage was designed using the Rational Method (Q = CIA) in accordance with the Orange County Hydrology Manual. A network of 13 catch basins, 27 manholes, reinforced-concrete pipes, and three box-culvert headwalls was sized to convey peak stormwater runoff from the project site to San Juan Creek.

The final plan set was drafted in Autodesk Civil 3D and compiled into a complete set of construction documents for submission to the City of Mission Viejo. The plan set includes plan and profile sheets for all three roadway segments, typical cross sections for each roadway classification, utility layout sheets showing proposed water and storm drain infrastructure within the right-of-way, and a quantities sheet summarizing materials and construction items. A quality assurance and quality control review was conducted on the typical sections to verify compliance with OCPW standard plans, and sections were redrafted as needed to ensure accuracy across all roadway classifications before final submission.

Outcomes

Anteater Transportation Engineering delivered a complete roadway design package for three segments within Rancho Mission Viejo, providing the City of Mission Viejo and HDR with construction-ready documentation for a new roadway corridor totaling three-fifths of a mile.
The final deliverables include a full Civil 3D plan set consisting of plan and profile sheets, typical cross sections, and utility layout sheets for water and storm drain infrastructure across all three roadway segments. Pavement design calculations were completed for both HMA and JPCP alternatives, with the 50-year life cycle cost analysis confirming Hot Mix Asphalt as the more cost-effective choice at a structural pavement cost of $2,587,200. The drainage network was fully designed and sized, with a total drainage cost of $1,471,012. Earthwork cut and fill volumes were quantified using a 1:1 reuse factor, with a total earthwork cost of $8,769,075. The total project cost estimate, including design fees and construction administration, came to $16,034,109.

All design elements were developed in compliance with Orange County Public Works standards, the Caltrans Highway Design Manual, the AASHTO Pavement Design Guidelines, and the Orange County Hydrology Manual. The project was presented at the UCI Senior Design Symposium in June 2026, where the team received the Crowd's Choice Award in recognition of the quality and clarity of their work.

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