Washington (CNN) — One of two piers at the port serving the Haitian capital has reopened, and a gravel road was laid off of it, clearing a major route for aid to come into the city, officials said.

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A Dutch Navy ship, the Pelikaan, unloaded 90 tons of humanitarian aidyesterday. Two other ships previously offloaded containers for trucks to carry supplies into Port-au-Prince, Haiti.

However, the road only allows for one-way traffic, and because of concerns about the pier, only one truck was allowed on it at any time.

The reopened pier is the city’s south pier, a smaller and older one. The north pier was rendered impassable by the 7.0-magnitude quake that struck Haiti January 12.

The road was opened through a joint operation with Haiti port authorities and the U.S. military, according to Coast Guard Lt. Cmdr. Mark Gibbs.

Repairs on the pier continue, Gibbs said. “We’re working on it. We’ve got a long ways to go … if we lose this pier, that’s it. We can’t bring in anything.”

U.S. officials say they have been taking steps to get aid into Haiti more quickly. A senior administration official involved in the aid operation said the speed of aid delivery is improving, with as many as 100 flights a day coming in now, compared to 25 flights per day just after the earthquake hit last week.

The official acknowledged that not all aid, particularly medical supplies, was getting through fast enough, but said that in recent days, at least half of the flights entering Haiti are carrying humanitarian supplies, and most of the other flights, including those of the U.S. military and foreign governments, are still carrying some kind of aid.

The official attributed the slight delay in getting aid through to two factors.

Dozens of planes were flying into the Port-au-Prince airport, carrying a variety of food, water, medicine and search-and-rescue gear.

The official, who spoke on condition of anonymity, said military personnel on the ground were sometimes confused about what the planes were carrying.

The military will now station aid officials in the airport control tower to assess the contents of each flight to ease the flow of aid.

Also, a Web-based system has been created so that aid groups, donor countries and others can track when each flight is scheduled to land and the supplies it has aboard.

The official also said the operating procedure of the U.N. Stabilization Mission in Haiti (MINUSTAH) says it can work without security only during daylight. The arrival of U.S. troops means they can take over a large share of security and speed up the processing of aid.

“Realistically, I am aware of the difficulties that this terrible natural disaster has posed,” Secretary of State Hillary Clinton said earlier Wednesday.

The senior administration official said that more than 300 aid distribution sites are up and running, in which more than 400,000 meals and humanitarian rations and more than 600,000 bottles of water have been delivered.

Clinton said she was impressed by how much had gotten done, considering “so many challenges that had to be addressed all at once.”