Securing a parking area with an impressive rockfall and avalanche defense dam

Overview

In May 2021, a significant rockfall event occurred at the Stubai Glacier cable car parking area, with three large rocks, each up to 100 m³, fortunately resulting in no injuries. To prevent future incidents, the existing rockfall protective dam, constructed in 2015, was planned for extension. This extension aimed to enhance both rockfall and avalanche protection for the parking area.

Challenge

The primary challenge following rockfall in May 2021 was conducting necessary surveys for planning, including rockfall and avalanche simulations, and securing timely approvals due to the area's environmental protected status and water rights considerations. Another significant challenge was the time constraint faced by the construction companies and Solmax. The project needed to commence by early October 2021 at the latest to be finished before November 2021, to assure a smooth start into the winter season for the Ski lift operator.

Solution

The protective dam, built as reinforced soil on the rim of the parking area, features a stone facing in the critical rockfall zone and vegetated slopes elsewhere. Its height of over 10 m and length of 180m was determined by rockfall simulation, and the dam has a total volume of 18,100 m³ (639,539 ft3). Materials for the dam were sourced from a nearby sediment retention basin above the Gamsgarten cable car valley station. Solmax supplied the project-specific produced MIRAGRID® GX 320/150 and all other needed geosynthetics within a four-week lead time, enabling the timely completion of the Polyslope® S System in just six weeks. This rapid response ensured that the parking area was protected for the upcoming winter season, offering guests a safer experience.