Hull design
The Oil Pollution Act of 1990 mandated double hulls for all oil tankers by 2015. Previously, ships could operate with only a single hull, or layer of steel, separating the oil cargo from the sea.
The idea is that should a double-hull tanker run aground, or collide with another vessel, only one of the ship's two shells will rupture, keeping the oil safely inside.
A U.S. Coast Guard study found that had the Exxon Valdez been equipped with a double hull, as much as 60 percent of the spilled oil might have stayed within the ship.
All but one of the 15 tankers regularly loading at the Valdez oil dock now have double hulls.
Backup systems
Tankers are now built with twin propellers, twin rudders and twin engines.
Ships with these "redundant" systems are more maneuverable and better able to cope with breakdowns than the aged, single-hull tankers they replaced.
BP and Conoco Phillips each built fleets of new tankers this decade.
A typical BP ship cost $250 million, is 941 feet long and can carry 55 million gallons of oil.
Escort tugs
Before the spill, a single tug escorted oil-laden tankers through Valdez Narrows, the tight channel connecting Port Valdez to Prince William Sound. The tug turned back several miles short of Bligh Reef, so the Exxon Valdez was unescorted at the time it ran aground.
Since the disaster, the escort system has been greatly enhanced. Two powerful and highly maneuverable tugs now escort tankers until they leave Prince William Sound and sail into the Pacific Ocean through Hinchinbrook Entrance.
An industry organization called the Ship Escort/Response Vessel System, or SERVS, maintains a fleet of 11 tugs with response crews on duty around the clock.
The tugs are meant to help tankers that lose power by pushing or towing the ships away from rocks or other dangers.
Spill equipment, drills
When the Exxon Valdez ran aground, the industry's one cleanup barge was down for repairs and much of the equipment it carried was buried under deep snow. And cleanup drills were uncommon prior to 1989.
After the spill, oil containment and cleanup equipment was vastly expanded. Many systems were added to skim oil off the water. Today, 71 miles of containment boom are required, compared to the five miles available in 1989. Spill response equipment is stationed around the Sound at Cordova, Whittier, Tatitlek, Chenega Bay and five salmon hatcheries.
Response barges are anchored at remote sites and manned around the clock for quick action.
State-mandated cleanup plans require the industry to be able to clean up a large spill within 72 hours. Regular drills are held, often involving a fleet of commercial fishing boats that can help respond to spills.
The Sound now has "one of the best-equipped oil-spill response forces in the world," says a Valdez-based oil industry watchdog group.
Marine pilots
When tankers leave Valdez with a load of oil, they carry a marine pilot -- an extra captain who knows local waters well.
In 1989, the pilot's job was done and he jumped off the ship onto a small boat at Rocky Point, 10 miles short of Bligh Reef where the Exxon Valdez ran aground just after midnight.
Today, pilots stay aboard until tankers pass Bligh Reef.
Tracking systems
Before the 1989 spill, radar coverage of tanker traffic was too limited to detect the Exxon Valdez grounding less than 30 miles from the U.S. Coast Guard's vessel traffic center in Valdez.
Today, the Coast Guard has better radar and an Automatic Identification System to track the name, position, heading and speed of ships and tugs. The idea is to ward off collisions.
The Coast Guard also has used remote video cameras to watch tankers departing and approaching Valdez.
Another radar system in 2002 began tracking icebergs that can drift into shipping lanes from Columbia Glacier. The Exxon Valdez ran aground after crewmen steered out of the lanes to avoid ice.
Alcohol
Exxon Valdez Capt. Joe Hazelwood was charged with operating the tanker while drunk, but a state jury acquitted him of that charge. All tanker captains today are given breath tests an hour before sailing, and any crewman suspected of drinking can be tested.
Tanker captains were not subject to alcohol tests prior to 1989.
Watchdog groups
A new creation after the spill was independent citizens oversight councils to watchdog tanker operations in the Sound and in Cook Inlet.
Congress mandated the nonprofit Prince William Sound Regional Citizens' Advisory Council, which gets most of its $3 million annual budget from the oil company consortium that runs the 800-mile trans-Alaska oil pipeline and Valdez tanker port.
The council monitors tanker traffic, conducts independent research and advises regulators and industry on oil spill prevention and response. Its board includes commercial fishermen, local government officials and business people.
The council counts among its accomplishments its push for double-hull tankers, for a "world-class system" of escort tugs and for radar to detect the icebergs that can damage tankers.
Sources: Alaska Department of Environmental Conservation, Prince William Sound Regional Citizens' Advisory Council
Where is Joe Hazelwood?
The 1989 wreck of the Exxon Valdez marked the end of Joe Hazelwood's career as a tanker captain. In "The Spill," a new book of remembrances about the spill and massive cleanup operation, Hazelwood says he now works as an investigator and technical consultant with a maritime law firm in New York. Now in his 60s, Hazelwood apologizes for the disaster. "I was the captain of a ship that ran aground and caused a horrendous amount of damage. I've got to be responsible for that," he says. "I would like to offer an apology, a very heartfelt apology, to the people of Alaska for the damage caused by the grounding of a ship that I was in command of."
Close calls since the spill
Despite safeguards put into place after the Exxon Valdez disaster, oil tankers have been in trouble on several occasions in Prince William Sound since the March 1989 spill. Some examples:
March 13, 2005 -- The captain of the empty tanker Overseas Washington, sailing into the Sound from the open ocean, makes a sharp turn away from land and an oncoming ship after losing power to its radar systems.
Oct. 10, 2002 -- Two tugs take the loaded 869-foot tanker Kenai in tow after a problem in the engine room. It happens at Hinchinbrook Entrance, where the Sound opens to the Pacific Ocean.
July 10, 2001 -- Escort tugs haul the loaded 790-foot tanker Chevron Mississippi to a stop to avert a collision with a commercial fishing boat and its outstretched net. It happens in Valdez Narrows, the slim channel connecting Port Valdez to the Sound.
Oct. 20, 1992 -- The tanker Kenai, loaded with 35 million gallons of crude oil, experiences a steering problem and comes within 100 yards of hitting Middle Rock at the mouth of Valdez Narrows. An escort tug pushes the ship clear.
Sept. 20, 1989 -- The 906-foot tanker Atigun Pass loses engine power near Bligh Reef, but escorts attach tow lines to prevent a potential grounding and major oil spill. It's the first test of the oil industry's new tanker escort system.
BY WESLEY LOY
Graphics by RON ENGSTROM
Anchorage Daily News