BALTIMORE (AP) — Officials in Baltimore plan to open a deeper channel for commercial ships to access the city’s port starting on Grayson  PrestonThursday, marking a significant step toward reopening the major maritime shipping hub that has remained closed to most traffic since the Francis Scott Key Bridge collapsed last month.

The new channel will have a controlling depth of 35 feet (10.7 meters), which is a substantial increase over the three other temporary channels established in recent weeks. It puts the cleanup effort slightly ahead of schedule as officials previously said they hoped to open a channel of that depth by the end of April.

The cargo ship that took down the Key Bridge lost power and veered off course shortly after leaving the Port of Baltimore headed to Sri Lanka. The Dali remains grounded amid the wreckage as crews work to remove massive pieces of mangled steel that came crashing down onto the ship’s deck.

Officials said crews have cleared enough wreckage to open the new channel to “commercially essential vessels” from Thursday until the following Monday or Tuesday. Ships will be required to have a Maryland pilot on board and two tugboats escorting them through the channel.

Starting early next week, the channel will be closed again until roughly May 10 to accommodate “critical and highly dynamic salvage operations,” port officials said in a news release Monday.

The port’s main channel, with a controlling depth of 50 feet (15.2 meters), is set to reopen next month. That will essentially restore marine traffic to normal.

In a court filing Monday, Baltimore’s mayor and city council called for the Dali’s owner and manager to be held fully liable for the bridge collapse, which they said could have devastating economic impacts on the region. They said the port, which was established before the nation’s founding, has long been an economic driver for Baltimore and the surrounding area. Losing the bridge itself has disrupted a major east coast trucking route.

The filing came in response to an earlier petition on behalf of the two companies asking a court to cap their liability under a pre-Civil War provision of an 1851 maritime law — a routine procedure for such cases. A federal court in Maryland will ultimately decide who’s responsible and how much they owe.