2025-2026 Senior Project (Team 3) — CPP Transportation Engineering Department

Apple Valley State Route 18

Improvements Project

Background

The Project focuses on a one-mile segment of State Route 18 in Apple Valley, extending from Navajo Road to Central Road. This corridor functions as a key east–west route for both regional and local traffic, with a unique layout that includes outer highways providing access to nearby businesses and residences. However, studies found show that this unique corridor creates multiple conflict points which lead to an increase in broadside collisions. Additionally, with the ever-growing businesses along the Project site, the corridor lacks multimodal infrastructure, highlighting the need to address improvements.

Alternatives

Deliverables

Our Team

Public Service Announcement (PSA)

Navajo Road to Central Road

Apple Valley, CA

Alternatives

Alternative 0: No Build

Existing conditions of the intersections will remain in place. The No Build will leave the current conditions as is, no development, design, or construction will go into effect.

Alternative 1: Outer Highway 18 Enhancements

The Outer Highway 18 Enhancements alternative will address the usage for all modes of transportation along the corridor. This alternative aims to reduce turning speed by proposing bulb-outs at key intersections. Additionally, the outer highways will be converted to one-way travel with proposed bike lanes and implemented bus pads along these roads which will continue to provide parking for access to businesses along the project site. Finally, additional bike lanes along the intersecting roads of Navajo, Quinnault, and Central are proposed with included road diets. In order to construct the enhancements along the outer highways, right of way is required.

GAD

Alternative 2: Roundabouts

The Roundabouts alternative will build off Alternative 1, implementing the same road diets and proposed multi-modal connectivity improvements. Additionally, this alternative will add two roundabouts at the Navajo and Central intersections. In order to maintain existing access to the businesses along the Project Site, the outer highways will be realigned and two proposed cul-de-sacs will be placed along the north-west and south-east outer highways at the Navajo and Central Road intersections respectively, which will require parcel acquisition.

GAD

Alternative 3: Michigan Left

The Michigan Left alternative builds off Alternative 1, implementing similar road diets and proposed multi-modal connectivity. Additionally, this alternative will build off of Alternative 2, which proposes a realigned frontage road along the north-west Navajo Road intersection, which includes parcel acquisition. This alternative aims to reduce conflict points at the intersections along SR-18 by restricting Left-turn movements at all intersections between Navajo and Central Road and replacing them with proposed U-turn lanes that will be implemented between intersections. In order to complete this design, the median along SR-18 will be widened to allow for all vehicle types to perform U-turn movements.

GAD

Deliverables

The Preliminary Environmental Analysis Report (PEAR) provides a comprehensive review of the environmental investigations based on environmental impacts such as biological, paleontological, climate change, hazardous materials, and even some social impacts such as Cultural, visual, and community impacts.

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The Project Study Report (PSR) summarizes the technical analyses, design concepts, and environmental considerations used to identify a recommended alternative. The PSR serves as the basis for future project development and coordination with local and regional agencies.

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The Intersection Safety And Operational Assessment Process (ISOAP) provides a comprehensive review of the traffic investigations based on the interaction between the freeway mainline, ramp terminals, pedestrians, cyclists, and transit. The ISOAP uses existing conditions, active transportation facilities, transit routes, crash analysis, and Safe Systems Approach in the data analysis.

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Benefit/Cost Analysis

Evaluates the benefit to cost ratios for each proposed alternative based on the total vehicle delays, overall traffic safety, emissions rates, and reliability.

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