A 612-foot sulfur tanker today smashed through the only bridge linking this small industrial city with the James River plantation country where many Hopewell workers live.

Motorists whose cars were stopped on the bridge waiting for its elevated draw span to lower abandoned their vehicles and raced for safety as the ship, its horns blowing a warning, bore down on them. When the grinding collision knocked out a 60-foot metal bridges section, four empty vehicles tumbled into the James River.

Police said only the bridge tender, Henry C. Frazier, 63, who was trapped in a small metal control room 75 feet above the river, was injured in the accident, which occurred shortly before 7 a.m.

The collision was another economic setback for Hopewell (population about 24,000), which was once the center for the manufacture of the pesticide Kepone - the cause of an ecological disaster whose magnitude still has not been gauged.

State highway engineers said it will probably take up to a year to repair the nine-year-old span and that repairs would cost at least $2 million.

The ship, the U.S.-flag Marine Floridian, knocked out a section of the bridge to one side of the span's draw metal towers to allow river traffic to pass beneath. The ship ground to a halt under one of the towers.

Coast Guard safety officers warned shortly after checking the ship that if it moves "at all," the entire $5.5 million draw span is likely to topple into the river.

Thousands of Hopewell area chemical workers who use the bridge to commute will have to take a 45-mile detour through Richmond, about 20 miles northeast of here, until the bridge, named for Benjamin Harrison, a three-time Virginia governor and signer of the Declaration of Independence, is reopened.

"We always make do some way," said Hopewell Mayor Helida Traina, after the collision. In 1976, Hopewell gained national attention as the town where the highly toxic Kepone was produced and allowed to be poured into the James, poisoning fish along 80-mile of the huge, meandering river.

Bridge tender Frazier he looked up from his control panel at 6:48 a.m. and saw the tanker coming sideways toward the bridge. Coast Guard officials said the steering mechanism of World War II-vintage tanker apparently failed as the ship approached the bridge.

A ship's pilot, identified by the Coast Guard as Frederick Luke, frantically blew six sharp blasts on the Marine Floridian's horn - an international danger signal. Frazier said scores of people lining the bridge to watch the ship, large for waters this far inland, began scrambling madly for the north shore, leaving their cars behind.

The ship's two anchors were dropped and its engines reversed before it hit the span at 6:50 a.m., Frazier said. That had slowed the ship's speed markedly he said. Otherwise, "she'd have took everything," he added.

As it was, Frazier was knocked to the floor of his control room by the impact and was later taken to a local hospital after complaining of neck and chest pains.

A Coast Guard buoy tender following the ship immediately launched lifeboats but no one was found in the water and police later said all those on the bridge apparently had fled safely on foot.

Nearly 480 feet of the tanker, which had just discharged a load of molten sulfur at Allied Chemical Corp.'s huge complex here, slid under the bridge before its superstructure came to rest against the bridge's green metal frame.

Coast Guard Capt. Claude Thomspon said later that the ship probably couldn't be moved for "at least one month" and cautioned that the river would probably also be closed to commercial shipping for an equal period.That will force closing of shipping to Richmond and Hopewell.

Neither the Marine Floridian nor any of its crew were reported seriously injured in the accident. The ship, run by the U.S. Commerce Department as the Paoli until 1966, is one of a fleet of 15 tankers owned by Marine Transport Lines of New York, according to the Tanker Advisory Center of New York. Marine Transport is partly owned by GATX Co. of Chicago, a large transportation leasing concern.

Ships bearing U.S. registry are required to meet more stringent safety standards than some foreign flag ships, such as the Liberian-flag Argo Merchant, which have been involved in recent major shipping accidents. According to one tanker expert, the Marine Floridian would be required to maintain an auxiliary steering room to press into service if the ship's navigation equipment failed.

However, he said, in most U.S. merchant ships it "takes quite a while" to get the auxiliary steering in operation. Navy ships by contrast maintain a manned "after steering" compartment to take control immediately of a ship's steering in case of equipment failure.

Coast Guard officials said a three-member board of investigation probably will be convened to determine the cause of the accident, the first ever to the Hopewell span.

Frazier and eye-witnesses on shore said that when the collision came there was a small explosion on the ship's bow, apparently the result of snapped electrical circuits on the bridge. A cloud of what Frazier said was sulfur came off the ship's deck and momentarily obscured his view of the river, he said.

Frazier, a bridge tender for the state for 15 years, said he realized the ship was going to hit the bridge long before it did, but realized he could not make it ashore safely. "I thought to myself how the hell to get out of here, but there wasn't no place to go," he said.