Diablo Road Trail

For three decades, the Danville Townwide Trail Plan (adopted 1989) envisioned closing a multi-purpose trail gap between the existing Barbara Haile Trail and access to Mount Diablo State Park. This public trail segment is one of the most difficult to secure and complete given that it would need to traverse across the privately-owned Magee property, a creek, as well as hilly terrain in a short (but challenging) section.

Map of Danville showing the Existing Diablo Road Trail and Trail Study Corridor

The opportunity came with the review and ultimate approval of the 69-home Magee Preserve project, which dedicated 93% of the 410-acre ranch to public open space and trail development.  As a condition of its approval, the project developers would construct the eastern 3,750 linear feet of the trail as part of the subdivision (shown in dashed bright yellow line).  The project is also required to dedicate a public easement to the Town for the future construction of the remaining western segment of the trail with the length to be determined based on final alignment (dashed orange line).  

Map of Danville showing Town Constructed Trail Segment, Developer Trail and Barbara Haile Trail

Most of the trail would be constructed on relatively flat terrain, following an existing emergency vehicle access (EVA) alignment.   The western most portion of the trail encounters the most challenging conditions, which include creek crossings, steep slopes and the most appropriate location to cross Diablo Road to connect to the existing Barbara Haile Trail.  

Diablo Road Trail Conceptual Alignment and Feasibility Analysis front cover

Therefore, much of the project design and preliminary analysis to date is focused on the farthest western portion of the trail’s development.  As an example, the Diablo Road Trail Feasibility Analysis, undertaken in 2018, focused on identifying a range of possible roadway crossings (connecting to the Barbara Haile Trail), creek crossings and three possible alignments to traverse hilly terrain along the western most segment of the trail. This analysis serves as the foundation for detailed evaluation in later project development phases as well as the basis for federal and state grant applications.

In spring 2020, a detailed in-house assessment identified a potential fourth trail alignment option (shown as the dotted orange line below).  While this alignment is not free of challenges, it appears to be the most environmentally friendly with the least amount of grading and earth disturbance.  Consequently, it would also be the least expensive. Finally, because it would comply with accessibility standards, this alignment would enable the project to be more competitive in grant applications. The Town’s next steps would involve moving forward and exploring this fourth trail alignment after conducting a detailed topographic survey.

Aerial View showing Hill Alignment Options from the 2018 Feasibility Study and In-house alternative

Project design elements of the potential 4th trail alignment would include:

  • Roadway crossing at Fairway Drive, connecting trail users from the Barbara Haile Trail to the new Diablo Road Trail
  • An 8-foot wide paved trail, tucked between the south side of Diablo Road and north of Green Valley Creek
  • Paved pathway would be separated 4-5 feet from Diablo Road, with a physical barrier installed to enhance trail user safety
  • Mechanically Stabilized Earth (MSE) walls would be used to stabilize the creek bank as well as to create pathway width adjacent to the creek
  • Pathway would be compliant with accessibility standards
  • Estimated cost: $4 million (project has a current $2 million funding gap)

STATUS & NEXT STEPS

In October 2020, this option was reviewed by both the Danville Town Council as well as the Parks, Recreation & Arts Commission.  Upcoming steps in the project design and development process include:

Spring 2020 In-house alternative
Summer 2020In-house preliminary design; grant submittals
Fall 2020Project area specific topographic survey to confirm alignment feasibility
Beginning 2021Environmental assessment and regulatory permitting process (estimated 12-18 months)
Winter 2021Diablo Road/ Fairway Drive crossing design
Winter 2021Final design begins
TBDBid process and construction (funding dependent)