Juneau's Thunder Mountain Bike Park Revolutionizes Trail Building with Crushed Shale

Juneau, Alaska, a locale notorious for its abundant precipitation, presents significant hurdles for constructing and preserving outdoor trails. However, the Juneau Mountain Bike Alliance (JMBA) has ingeniously addressed this challenge by incorporating crushed shale, a naturally occurring sediment derived from river systems. This innovative approach has been successfully implemented at the recently completed Thunder Mountain Bike Park and is now being extended to other nearby trail networks.

The Thunder Mountain Bike Park, situated within the Under Thunder Trail Network in Mendenhall Valley, marks a pioneering effort as the region's first purpose-built bike park. Boasting seven trails, six of which are designated for downhill-only use, the park caters to various skill levels with green, blue, and black rated routes. Reid Harris, a co-founder and former president of JMBA, highlighted the park's design philosophy, emphasizing a progressive development where trail features evolve from simple rollers on green trails to complex doubles on black trails, often incorporating wooden structures. Notably, the 'Thunder Mountain Uptrack' stands as the sole multi-directional trail, serving both as a descent and the primary ascent route from the Under Thunder trailhead, while 'Dream Zone' offers a dedicated green descent option. Advanced riders can test their skills on trails like 'Bob Gnarly' and 'BTV', featuring challenging jumps and technical elements, including an imposing eight-foot air gap with a two-foot step-up. For those seeking a more traditional singletrack experience, 'Paydirt' offers a longer, more elevation-dropping ride, distinguishing itself from the typically shorter and flatter trails within the park.

The efficacy of crushed shale as a construction material lies in its abundant local availability and exceptional properties. Harris explained that this distinctive soil, characterized by its platelet-like rock structure, compacts efficiently and sheds water effectively, a crucial advantage given Juneau's annual average of 60 inches of rainfall. This natural aggregate requires minimal upkeep, with some trails built five years ago still in excellent condition. Furthermore, its use indirectly benefits the local salmon population by preventing the accumulation of sediment in their spawning grounds. The city's continuous removal of shale from river catchment systems provides a sustainable source for JMBA, enabling them to armor trails and expand their reach to more distant areas, despite the increased logistical effort and cost. The development of Thunder Mountain reflects a growing demand for specialized mountain biking trails in Juneau, particularly among younger riders seeking gravity-focused experiences. The strategic placement of the park in Mendenhall Valley, home to a significant portion of Juneau's population and numerous young families, aims to provide accessible and skill-progressive riding opportunities. JMBA is already planning an adaptive trail between 'Dream Zone' and 'In the Gnome of Love', ensuring crushed shale will continue to be a cornerstone of their future trail-building endeavors.

This innovative use of natural resources to create and maintain high-quality recreational spaces demonstrates a commendable blend of environmental consciousness and community engagement. By transforming a geological characteristic into a sustainable solution for trail development, Juneau is setting a precedent for resilient and responsible outdoor infrastructure. Such initiatives foster a thriving outdoor community, promoting health, skill development, and a deeper connection with the natural world, ultimately enriching the lives of residents and visitors alike.