Ramp metering to go live

By Leon Engelbrecht, ITWeb senior writer

Johannesburg, 26 Sept 2007

Ramp metering has arrived for motorists using the N1 highway between Johannesburg and Pretoria. It forms part of the SA National Road Agency Limited's (Sanral's) ongoing efforts to use IT to keep traffic flowing on Africa's busiest road.

A ramp meter is a smart traffic light on the onramp to a highway that, by alternating between red and green every few seconds, breaks up the flow of traffic onto the freeway. The meter is supervised real-time by closed-circuit television (CCTV) and via an intelligent traffic (i-traffic) management system.

"At a certain point, you have a breakdown in the flow of traffic and everything slows to standstill," says Sanral toll and traffic manager Alex van Niekerk. "Metering will attempt to keep the traffic flowing."

The year-long pilot project will see ramp meters on the southbound onramps of the N1, at Samrand and New Roads, as well as at the N1-Old Johannesburg Road intersection. There is another on the northbound onramp to the N1, at New Road, in Midrand, to be joined shortly by a ramp meter at Samrand Road.

Constantly monitored

Van Niekerk says acceleration lines will be painted onto the road to further aid traffic flow. "The expectation is that these two measures should improve traffic flow on the freeway."

He adds that the ramp meters and their effectiveness will be constantly monitored, especially their impact on the roads surrounding the onramps. The frequency of the lights - the length of time they flash red or green - can be adjusted remotely and, should traffic on the ramps back up substantially, the lights can be set to green.

Other i-traffic measures already in place include CCTV along most of Gauteng's highways, as well as electronic variable messaging boards. The CCTVs are linked by fibre optic cables to a central control room, in Midrand.

At its launch last year, the project was valued at about R100 million. At the time, transport minister Jeff Radebe said the ever-increasing traffic congestion on the province's roads was impeding economic growth.