Bush Highway Animal Warning Systems Minimize Collisions

Challenge: Bush Highway is owned and maintained by Maricopa County and is in the northeast portion of the county within Tonto National Forest. Approximately 400 horses, collectively known as the Salt River Horse Herd, reside along the Salt River surrounding Bush Highway.

Apart from horses, the Salt River basin is a habitat for other animals, such as deer and bighorn sheep. Among crashes recorded in the subject corridor, approximately 20% involved animals, with nearly 60% involving horses. Salt River Wild Horse Management Group (SRWHMG) is a volunteer group that monitors the horses and their wellbeing. It maintains the fences along the corridor to channel horses to defined crossings.

Maricopa County DOT sought to implement safety measures to warn drivers regarding the presence of animals in the vicinity of animal crossings and minimize animal-vehicle collisions (AVC).

Solution: The design team worked on this unique project to evaluate the impact of the Salt River Horse Herd on traffic operations along Bush Highway and to identify solutions for animal warning systems to enhance the safety of drivers and horses alike. They found that horse crossing activity increased significantly at night when visibility was low (this section of Bush Highway is within the Tonto National Forest), and travel speeds were well above posted speed limits.

The team created a conceptual design that took a multi-pronged approach involving radar-based detection, fencing, dynamic speed feedback signs, and dynamic message signs. The approach focused on channeling horses to preferred crossing locations, detecting horse activity at target locations, warning drivers during crossing activity, and driver speed feedback.

Benefit: This was a sensitive issue for the Salt River Wild Horse Management Group. The Group was vocal and organized to get the law enacted to provide protection to the herd.

Working with the Maricopa County DOT to solve this unique issue, the ITS system warned drivers and reduced the crashes involving animals along the corridor.