EVEN if the onslaught of mega ships were taken out of the picture, container ports in North America would still face congestion issues today, as continuing growth in box traffic is stretching port and intermodal infrastructure to their limits, says a senior shipping executive.

"Congestion was inevitable," Hyundai Merchant Marine Americas CEO David Arsenault told the Propeller Club of Los Angeles-Long Beach, reported IHS Media.

With growth between three and five per cent each year since the recession hit in 2009, box volumes have returned to pre-recession levels.

Ports that were struggling to handle the traffic in 2006-07 are now experiencing the same problems with inadequate infrastructure that were present eight or nine years ago.

The port and shipping industry knew as far back as 2002 that marine terminals, intermodal rail connectors, roadways and truck capacity were beginning to stress under growing imports from China. "China could pitch more than we could catch," Mr Arsenault said.

Furthermore, shipping patterns have become more complex. Many of the carriers operate in vessel-sharing alliances, which distribute containers from as many as six different lines across the port complex.

The model of carrier-owned chassis is gone. Most of the equipment is now provided by three large chassis-leasing companies.

Drayage industry capacity problems, whether due to a shortage of drivers or long waits at terminal gates, contribute to congestion, Mr Arsenault said.

Intermodal complexity is also a contributor. Citing the situation in Los Angeles-Long Beach, he noted there are 13 on or near-dock rail transfer facilities in the harbour area.

The increasing calls by mega ships, which in southern California generate from 5,000 to more than 10,000 container moves in each call, was the final blow contributing to port congestion, Mr Arsenault said.