However, the Department of Regional Development (DRD) has said that most of the work will be carried out during off-peak hours in order to minimise traffic disruption.

BBC: Bus lane

If traffic congestion can be compared to water flowing through a sink drain, then a congestion toll is like the handle on the spigot -- it increases during times of peak road use, decreases during off-peak times, and is adjusted in real time to keep traffic flowing smoothly.

CNN: Road tax alternative: Pay for each mile you drive

Now Experian Hitwise is reporting a significant drop-off in Groupon traffic this summer, nearly 50% since its peak in the second week of June 2011 compared to last week.

FORBES: Groupon's MySpace Moment?