Steep river banks and clay soil near highways have led to numerous slide events near Crookston, MN, over the past 50 years. In September 2003, a landslide in downtown Crookston between US Route 2 and the Red Lake River caused significant property damage, leading the Minnesota Department of Transportation (MnDOT) to investigate new monitoring solutions. The department had used traditional inclinometers, but were interested in automation and remote collection of data. A pilot project determined the viability of Measurand’s ShapeArray to be installed in two roadway sections experiencing stress related to erosion and soil instability.
ShapeArray data revealed that soil movements at the Crookston East site were deeper than anticipated. With this new data, experts determined that the slope was no longer creeping, but rather a major failure was occurring. The MnDOT closed the westbound lanes of US 2 and detoured traffic north of the city on Monday, Sept. 15, 2008. Ten days later, a large progressive landslide occurred, dropping a 150 m section of highway three metres. The slide continued over several days. ShapeArray helped engineers ensure that no members of the public were hurt during the sliding event.
ShapeArray survived unprecedented deformation during and after the event. The instruments continued to provide engineers with useful data until the slide forced the casing to move from their vertical down-hole position to a horizontal one. The system remains in place and provides valuable data to the MnDOT.