Greyhound's 3,800 buses remained parked Thursday as 12,700 union employees of the nation's largest intercity bus line went out on strike. The dispute is over their employer's insistence on a 9.5 percent wage cut and other ''give backs'' that the carrier said it must have for ''immediate competitive relief.''
The work stoppage forced thousands of passengers to crowd bus and train terminals seeking alternative transportation. Though other bus lines and trains were preparing to carry additional loads, the first day of what could be a long strike appeared chaotic in some areas.
Greyhound Lines Inc. ordinarily handles about 60 percent of all bus passenger mileage in the United States. Last year it carried about 57 million passengers. Nevertheless, the carrier contends that its labor costs are now far out of line with major competitors, some 30 percent to 50 percent higher. It says that ''realistic cuts are badly needed'' if Greyhound is to remain competitive.
Greyhound proposed the wage cut to the Amalgamated Transit Union and sought lower starting pay for all new employees. It also proposed a 5 percent employee contribution to the Greyhound pension fund (employees make no contribution now) and other concessions.
Rejecting the proposal, the union estimated that total concessions would cost employees 20 to 25 percent of their current agreement.