A 30km traffic jam on 27 August brought traffic to a standstill in a Hebei province section of the Beijing-Tibet expressway. The tailback was triggered by a car accident and road maintenance work.

The jam was the second serious hold-up on the road in the past two weeks. Other sections in Inner Mongolia, Shanxi and Hebei province also experienced congestion.

The worst jam began on 14 August, lasted nine days and trapped thousands of vehicles in a tailback that extended for more than 100km. That jam was caused by road maintenance work and an exceptionally large number of heavy trucks, especially ones carrying coal from China’s inland provinces to coastal ports.

While transporting coal by truck is more than twice as expensive as shipping it by rail, rail freight capacity is overloaded, the Financial Times commented.

China is investing huge sums in road and rail expansion programmes and coal shipments are a priority for the railways, but the expansion is programme isn’t happening fast enough to the relieve the railway transportation bottlenecks.

An increasing number of commuter journeys is another contributory factor, according to Zhao Jie, deputy director of the Urban Transport Institute under the China Academy of Urban Planning and Design. He told China Daily that highways have to cope with increasingly heavy traffic and commuter demands.

“Take Beijing for example, the city now has more than 4m vehicles and traffic jams are becoming common,” he said.