NEW DELHI - The Delhi government on Thursday unveiled its ambitious traffic rationing plan to combat rising pollution, but greens were unhappy over the exemption given to 25 categories of motorists including women drivers, bikers, emergency vehicles and a host of VIPs. The odd-even formula will be tried out for 15 days from January 1 between 8 a.m. and 8 p.m. except on Sundays, Chief Minister Arvind Kejriwal said.