The bitter three and a half week steel dispute - which came within 24 hours of crippling Australia's car industry - was resolved today, writes Mike Duffy.

But not before 200 Holden workers went on strike - costing the General Motors affiliate millions of dollars in greatly reduced production of cars for the domestic and export markets.

On a day which should have ended in celebrations for the four car makers, Holden was left counting the cost of another dispute.

BHP Steel resolved its dispute with 280 workers hours after mounted police wearing riot gear charged picket lines for the second day in a row to make way for truckloads of steel.

The parties struck a deal in the Industrial Relations Commission this afternoon after lengthy negotiations which began on Wednesday. BHP Steel agreed not to use non-union contract labour and agreed to drop legal action against 12 workers.

The deal is subject to the endorsement of union members at a meeting at the Victorian plant tomorrow, but this is seen as a formality.

Deliveries of steel began immediately, ensuring full production can be re-commended by Holden, Ford, Toyota and Mitsubishi from next week.

Holden, however, will have to settle another dispute - over too much overtime.

Two hundred day shift workers turned up for work at 7am in the plastics plant at Holden's South Australian assembly facility - and found 30 workers who had started at 3pm on Wednesday still on the job.

They immediately called a meeting to demand the company fast-track an agreement struck a month ago for an independent committee to examine the problem of staffing the plant's traditional bottleneck.

Management agreed to workers' demands - but refused to pay wages for the two hours they had been off the job for their unofficial stop-work meeting.

That prompted the workers to go on strike.

A worker earning an average $A18 an hour can earn $405 for a double shift - after receiving time and a half for the first three hours of overtime and double time for all subsequent hours.

With the plastics plant out of action, a reduced number of Commodores, Statesman Caprice and Monaro Coupes had to be assembled without bumpers and other components.

Australian Manufacturing Workers Union officials claim workers are regularly asked to work 16 and sometimes 20 hour shifts without a break.

Union state secretary John Camillo said: "Our members are just not prepared to wait until someone gets caught up in a machine through fatigue or crashes a car while driving home.

"The plastics plant has been a bottleneck for years - this is not a new problem.

"It's time Holden expanded the section and took on more workers. Young workers will always accept overtime - but the consequences of a tired worker operating machines are obvious.

"Following disputes in the supplier industry over the past year and the current problems at BHP, the last thing our members wanted was to disrupt production.

"But there have been extreme cases where workers have worked as long as 20 hours without a break.

"This is a health and safety issue and we are amazed Holden is not meeting its obligation in relation to duty of care."

Holden spokesman Tristan Everett said: "The issue not whether workers have had a 10 hour break (between shifts), but whether they have had adequate rest between shifts to safely perform their duties.

"There is an onus both on the individual to ensure they are in a fit and proper state to perform their tasks and on supervisors to determine their ability to perform their duties safely and properly."

Striking workers will meet tomorrow to decide whether to return to work, pending an assurance the committee will be set up to review overtime requirements.

In the meantime, Holden continues to refuse to pay wages for the two hour meeting.