Metropolitan Police were out in force encouraging drivers to drop off passengers at designated areas.

As many as 5,000 officers will be on school duty when other schools open tomorrow. Police say there are as many as 79 popular schools prone to traffic jams.

Traffic Control Centre deputy superintendent Lt-Colonel Wannarong Wonglee said traffic volume yesterday was heavy, especially near Assumption College on Sathorn and Sukhumvit Road around Soi 64.

He urged motorists to avoid these two areas during rush hour. He said city police had asked schools to warn parents to observe road and parking rules.

The Traffic Control Centre yesterday reported morning rush hour saw nearly all inner Bangkok roads heavily congested - including Lat Phrao, Vibhavadi-Rangsit, Phaholyothin, Ratchadaphisek, Rama 9, Phetchaburi, Sukhumvit, Rama 4 and Sathorn. Expressways and roads from Thon Buri were clogged, too.

Jams were particular bad near Bangkok Christian College and Assumption College, the report said.

It added many parents and drivers were ignoring requests to drop children off between 200 metres and 300 metres from school entrances.

Officers were distributing leaflets explaining drop-off and pick-up recommendations. Many parents walked younger children to school.

However, the centre said overall traffic control was satisfactory and officers worked hard to ensure a smooth flow.

The afternoon rush hour saw fewer problems as officers overcame snags experienced in the morning.