Engineers: attaching trail to Highway 82 at Shale Bluffs is feasible only with high risk and cost; boards favor pausing work

An engineering feasibility review presented June 3 to a joint session of the Pitkin County Board of County Commissioners and the Open Space & Trails Board found that directly attaching a trail to multiple Highway 82 bridges and retaining walls at Shale Bluffs is technically possible only with substantial additional investigation, very high construction risk and sharply higher costs.

SGM engineers said two reinforced concrete box culverts (the wildlife underpass and the Owl Creek culvert) could be extended to carry trail decking, and some bridge piers and abutments might accept independently framed attachments. But SGM cautioned that much of the 82 corridor there is lined by mechanically stabilized earth (MSE) walls and post-tensioned retaining structures whose facings and internal tendons cannot safely accept new loads without invasive work. Engineers described high-risk options that would require deep foundations, soil nails, specialty contractors and prolonged lane closures on Highway 82.

The firm estimated conceptual construction costs for the 1.3-mile 82 attachment alignment at roughly $20 million to $27 million, with an additional $150,000 to $250,000 needed immediately to complete the geotechnical and constructability investigations SGM judged essential before any design proceeds. SGM and county staff warned the $20–27 million figure could “balloon” as detailed subsurface and traffic constraints are resolved.

Why it matters: the attachment concept was proposed as a shorter, lower‑impact way to connect the Brush Creek Park‑and‑Ride and the Aspen Airport Business Center (ABC) with the Rio Grande/Stein trail corridor. SGM and county staff said that even if an attachment alignment could be built, it likely would not provide year‑round, safe separation from highway traffic; it would be costly to maintain and could reduce the effectiveness of an existing wildlife crossing unless specially upsized.

Board response and next steps: Open Space & Trails board members and several county commissioners told staff they no longer support further spending on the attachment-focused feasibility work. Several members said the attachment option has a “fatal flaw” because it fails to link the ABC to the Rio Grande Trail and would not realize the broader mobility benefits the community wants. Commissioners indicated they prefer staff and consultant time be redirected to the alternative “twin bridges” or single new bridge alignment options, to environmental analyses for bridge structures near the ABC, and to coordination with wildlife connectivity groups (Roaring Fork Safe Passages).

County staff said they will return in the fall with a full package of options — including the twin‑bridges alignment and on‑grade alternatives studied with Colorado Department of Transportation (CDOT) — and that a broader public outreach process will occur then. Staff also noted that any work adjacent to CDOT structures will require CDOT review and permitting, and that trail structures built against 25‑plus‑year‑old highway infrastructure will complicate long‑term maintenance plans.

Discussion highlights: engineers emphasized restricted access at Shale Bluffs, steep unstable slopes, and the need for crane‑mounted geotechnical borings and significant lane closures to do detailed investigation or construction. Open Space & Trails Board members and commissioners repeatedly cited traffic impacts, wildlife connectivity concerns, constructability and the comparatively poor user experience of a trail immediately next to Highway 82 as decisive negatives.

What to expect: staff recommended pausing further spending on the attachment study pending the additional targeted investigations already under way at the ABC and urged a fuller public process this fall. The county will continue coordination with the City of Aspen, CDOT and the Roaring Fork Safe Passages program while refining costs and schedule for bridge‑based alternatives.

Closing: staff said the Brush Creek–ABC corridor remains a long‑term priority; the question for leaders is which alignment — if any — achieves valley‑scale connectivity, wildlife connectivity and feasible construction and maintenance costs.