People are turning pessimistic about life in Los Angeles as the metropolitan area heaves against the social strains of gang violence, rising housing prices and traffic congestion made worse by the growing population, the Los Angeles Times Poll found in a new survey.

The clearest evidence of discontent came when people in Los Angeles County were asked how they feel things are going these days. In the latest poll, 52 percent said either fairly well or very well. But when the same question was asked less than three years ago, 70 percent said things were going well.Looking at the same issue another way, 43 percent said things were going badly today, compared with only 24 percent who viewed things badly in the March 1986 poll.

Further evidence of the pessimism arose when the poll asked people if they believed that the quality of life has changed for better or worse in the last 15 years, a period that has seen the population of Los Angeles County grow by about 1.6 million.

About 60 percent said life has changed for the worse, and only 17 percent said things have gotten better. About half of the people polled also said they had considered moving from Los Angeles in the last year.

Crime was cited as the strongest pressure forcing people to consider leaving Los Angeles. Most said if they did move, they hoped to stay somewhere in California, primarily in the southern half of the state.

As in previous polls, fear and resentment of crime were the strongest social pressures. Asked to say which problems were worst in their lives, 78 percent of the people mentioned crime. About 46 percent - including more than half of those polled at homes inside the city of Los Angeles - said they do not feel safe walking in their own neighborhood at night.

After crime, the physical environment was found to be the most criticized aspect of life in Los Angeles County. Traffic congestion, pollution and the all-encompassing issue of "growing population" were cited as serious problems by many people. With a sample of this size, poll director I.A. Lewis said, the poll is accurate to within 3 percentage points in either direction.

There was no lack of strong feelings about the bus service provided by the Southern California Rapid Transit District, with sentiment shifting decisively against the transit agency.

Exactly 50 percent of the respondents disapproved of the transit agency, while only 21 percent had a favorable response. Those findings are a sharp turnaround from a Times Poll in 1986 that found a 53 percent favorable rating of the agency, with only 27 percent unfavorable. Since that 1986 poll, bus service and management have come in for numerous bouts of criticism, including an abortive move by the Legislature to disband the agency.

There was strong support, meanwhile, for the idea of assisting in recycling by having residents separate their household trash into different containers. Under most recycling schemes, newspapers and easily recyclable containers such as drink cans and bottles are separated from the other trash. By a margin of more than 3 to 1, poll respondents said that separating trash is a reasonable thing to do.