O.C. Voters Approving Transportation Tax : Measure M: County’s first self-imposed tax increase in roughly 30 years appears to be winning.

Orange County voters were approving early today a sweeping package of highway and transit projects, financed by a half-cent sales tax. If would be the first self-imposed tax increase here in roughly 30 years.

Measure M backers were trying for the third time in six years to aid the county’s bedraggled motorists, who endure some of the state’s most congested highways.

Late Tuesday, after continually trailing with only a fourth of the precincts counted, Measure M opponents conceded defeat.

“I can’t for the life of me believe that they did this,” said Bill Ward, a spokesman for Drivers for Highway Safety, which opposed the measure. “They managed to target the right people this time. . . . I think it would take something miraculous to turn it around. I think it’s clear ‘M’ has passed.”

Board of Supervisors Chairman Don R. Roth said: “This is the No. 1 surprise of the whole election in Orange County. What’s happened is that every day 99% of us are sitting in traffic jams realizing that something has to happen.”

Passage of the measure would mean the half-cent sales tax would be imposed here to raise $3.1 billion over a 20-year period. Money would go for freeway improvements, reconstruction of the El Toro Y, for regional and local street projects, as well as for commuter rail and other transit programs.

The plan would cost each Orange County resident $50 to $75 a year.

Voters in the state’s other urban counties--including all of the counties bordering Orange County--already have approved such sales tax hikes for transportation.

The campaign for Measure M marked the third time in six years that Orange County voters had considered such a tax. Last year a nearly identical proposal lost by about 14,000 votes--53% to 47%. A 1-cent increase was soundly defeated in 1984, 70% to 30%.

Reed Royalty, a Pacific Bell executive who chaired the pro-M campaign, said the lead gave him confidence. “We did of course have a strong drive to vote by mail,” Royalty said, “and that’s where these votes are from. . . . I hope it means we’re going to win.”

Royalty, who was joined by about 15 supporters at the Measure M campaign office in Santa Ana, said that momentum in the past few days shifted in favor of the ballot measure. “We have tracked the trend with polls. . . . The last one we took was less than a week ago (Saturday) and it showed that with no information about the measure being given, 51% of the respondents would vote for it. When they were simply read the language that was on the ballot, the figure rose to 62%--a bit of a rise from what we had been seeing earlier.”

Proponents of Measure M mounted a $1.1-million campaign that included telephone calls to voters and computer-generated mail that resembled personal letters from a resident of each community to neighbors, and missives from the Automobile Club of Southern California.

The measure included something for everyone--growth controls, a citizens’ oversight committee, and a broad mix of projects to appeal to partisans of freeways, commuter trains and neighborhood streets.

Most of the campaign dollars came from developers and the construction industry, out of concern that worsening traffic congestion would hurt business and prompt a decline in Orange County’s quality of life.

But the campaign was low-key, with the mail not reaching voters until the final week before Tuesday’s balloting. Also, the proponents, led by Royalty, spent far less than the $2.4 million consumed in last year’s losing effort.

The opponents, an unlikely coalition of anti-tax and slow-growth activists, said they spent less than $1,000, held one press conference, and appeared in one televised debate on a station with a limited audience.

The opponents split, with some arguing against any tax hike and others claiming that it would promote new growth, thus canceling any gains in commute times. Still others said that Measure M’s funding for car-pool lanes and increased commuter rail service lacks merit.