On a normal day, 42 tankers, 19 freighters, 391 barges, 128 ferries and 2 cruise ships will move through the Houston Ship Channel. On any given day, a few of those tankers will be as long as 10 football fields.

The last week has been anything but normal.

The second busiest U.S. port by tonnage has been closed for four days by a poisonous cloud of cancer-causing benzene and toxic runoff that’s settled on the water from nearby chemical fires. It’s not the first time the channel has closed. Fog and hurricanes have closed it in the past. But the channel’s significance has grown almost daily as drillers in the shale fields of Texas have made the region one of the world’s fastest growing exporters of oil, gasoline and diesel.

In the past few days, about 60 ocean-going ships were unable to move either into or out of the region’s most important business artery, supporting roughly 12 percent of the nation’s refining capacity. But it’s not only the number of ships that makes the 1,000-foot-wide channel unique, or important. It’s also the size.

Houston Ship Channel
Houston Ship Channel

In the past year, because of the 45-foot depth at its center line, the channel has seen its first visits by both New Panamax ships, named to reflect the fact that their 1,200-foot lengths can only be accommodated by the new larger lock on the Panama Canal, and by so-called Very Large Crude Carriers, or VLCCs, tankers able to carry 2 million barrels of crude.

Challenging to Navigate

“The channel isn’t getting any larger, but the ships are,” said Chris Hebert, a meteorologist who tracks the Gulf’s hurricane and fog seasons for StormGeo, a weather service used by the Houston Pilots Association.

Even in good weather, navigating the Channel is challenging. Pilots passing one another perform a maneuver called the “Texas chicken” which requires setting a near head-on course, then swinging their bows away from each other before using the cushion provided by the other ship’s wake to swing their sterns out and come back to the center of the channel—all while avoiding any barges in the outside lanes.

The waterway was expanded in a decade-long project completed in 2005. Ships now transit the channel through a 530-foot wide center lane, flanked on both sides by 235-foot wide lanes for barges and tow vessels. The ship lane was dredged five feet deeper to 45 feet.

Safety Margins

“Anyone who thought we were getting increased safety margins out of that didn’t quite understand the nature of maritime traffic,” said Steven Nerheim, the retired Navy captain now directing the Coast Guard’s Vessel Traffic Service for Houston-Galveston. “What it got us was bigger ships.”

Restoring order after after a closure is a complex logistical feat for the port’s stakeholders, according to Nerheim. “We prioritize and open the valve slowly so that it doesn’t look like the Oklahoma land rush,” he said in a telephone interview.

“We’re always working to find a combination of mitigation strategies to continue moving an ever larger number of ever larger ships in a ship channel that’s not growing,” Nerheim said. “Even if we started digging tomorrow to widen it, it would take years to get it done. So my hope is that we start digging tomorrow because the traffic is here.”