The fate of an $8.4 billion highway and mass-transit program for the Phoenix area rested Tuesday with the voters, who were asked to add a half-penny to their sales tax to pay for the project.

Turnout of 30 percent to 35 percent of Maricopa County's 860,000 eligible voters was predicted in the one-issue special election.Maricopa County includes Phoenix, Glendale, Scottsdale, Tempe, Mesa and Chandler. The sales tax varies from city to city; the rate in Phoenix is 6.7 percent.

Recent polls indicated that the public was about evenly split on the program, which calls for a 103-mile elevated railway; an increase in the number of buses to 1,500 from 350; operation of a commuter train linking suburban Chandler, Mesa and Tempe with Phoenix, and accelerated freeway construction.