The road is divided into MAIN & SERVICE roads. MAIN is for bigger vehicles like Cars, Trucks etc. Service road is being used my Bikes and All kinds of puny vehicles (yes that includes Ghadha Gaaris as well :P)
It wasn't due to One Wheelers. The separation was much more logical and a good step by them i must say.
Now, NO stupid biker or pedestrian will try to cross the road, hence reducing the chance of any accident.
On a negative side, IF there is an accident, people around MAY not be able to help the affected.