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HKU Urban Studies and Planning team offers novel solution to a GPS blind spot for safer and smarter driving experience in multilevel road networks


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Multilevel road networks such as flyovers and overpasses are built in large cities to solve traffic congestion. Instant correct identification of the road level that a vehicle is driving in a multilevel road network is important to make driving more pleasant, safer, and smarter.

Vehicle drivers relying on GPS navigation who accidentally drive onto a flyover with intention only to proceed on the ground level will face this problem: the GPS navigation system does not realise the vehicle has entered a wrong level and continues to give instructions as if it were on the ground level. Only after quite a while will the system notice the wrong road level and begin to redirect to a new route.

Present vehicle navigation system that uses GPS with positioning error of 10-30 meters has a long existing problem in determining which road level a vehicle has entered, especially for flyovers parallel to the ground level. The problem often creates confusion and “motorway anxiety disorder” that makes people more prone to accidents in driving.

Professor Anthony Yeh Gar-On’s research team at the Department of Urban Planning and Design of the University of Hong Kong (HKU) offers a novel solution to this long existing vehicle navigation problem since GPS was used over 20 years ago by instantly identifying whether a vehicle has entered a flyover or is still on the ground level.

The Angle Difference Method developed by the team compares the inclination angle of a vehicle and angles of different road levels stored in a Transport GIS to determine whether a vehicle has entered the ramp of a flyover or still on the ground level. It uses an ordinary smartphone that can be put anywhere at any angle in the vehicle with a plugged in or installed onboard diagnostic (OBD) device.

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