Portable Queue-End Warning

Queue Warning Systems

What is a Portable Queue Warning System?

Permanent Queue Warning Systems have been around for a very long time. They are used to reduce rear-end collisions. They are installed at nearly every border crossing in North America and are used to warn drivers when a queue of slow or stopped vehicles are ahead allowing them time to slow down and prepare. Portable Queue Warning Systems take this exact same concept but implement it in a mobile solution so that it can be used for temporary conditions where significant queuing is present such as major road construction projects and large sporting events.

How does a Queue Warning System(QWS) work?

At a very basic level QWS works by monitoring the speed of vehicles along a stretch of roadway and then provides warnings to approaching drivers when a slow down is detected. In permanent installations, various sensors can be used to monitor speeds such as Inductive Loops, Doppler Radar, Microwave and Video Detection systems. Various warning systems can be used as well but typically this is achieved using a Variable Message Sign (VMS). With a Portable Queue Warning System, multiple radar sensors are used to monitor vehicle speeds and Portable Variable Message Signs(PVMS)are used to provide warning messages to drivers

How Effective is it?

Studies have shown that Queue Warning Systems can reduce rear-end and severe accidents by 18-45%(Source). This represents a huge improvement in safety both for the workers present in the work zone as well as the drivers passing through it.

Sample QWS Design

This is an example of an advanced Queue Warning Deployment. In this design the expected queue length was greater than 10km. In addition, two major expressways merged onto the primary expressway requiring supplementary PVMS to provide warnings to that traffic