JEFFERSON CITY, Mo. -- The Senate gave initial approval Wednesday to a proposal asking voters to approve a nearly $500 million tax increase for transportation.

The voice vote marked a major step toward success for transportation advocates, who saw a similar bill die without receiving a Senate vote in the final days of the 2001 legislative session.

This year's version still needs another Senate vote before going to the House, which has shown a greater tendency to support transportation funding measures.

The Senate legislation would ask voters to raise the motor fuel tax to 23 cents a gallon, up from the current 17 cents, and to increase the state sales tax by three-eighths of a cent to a total 4.6 cents on a dollar.

If approved by voters in August, the higher taxes would take effect in January.

The increases would generate an estimated annual revenue of nearly $500 million, with $385 million designated for state highways and bridges, $77 million for local roads, $27 million for other modes of transportation and $8.5 million for biodeisel and ethanol programs.

The proposal stops short of meeting all the state's transportation needs, which the Department of Transportation has estimated would take an additional $1 billion annually.

'Significant step'

"This bill is a significant step in improving the roads of Missouri ... but it does not fully address the needs," said sponsoring Sen. Morris Westfall, R-Halfway, who last year had opposed a similarly sized measure backed by Democratic Gov. Bob Holden.

Holden had promoted a $620 million transportation funding plan last year, then lent his backing to a $535 million plan that failed to come to a Senate vote. Although taking a more back-seat approach this year, Holden is solidly behind Westfall's legislation, said spokesman Jerry Nachtigal.

The legislation would raise an estimated $240.5 million annually through the fuel tax increase, with 70 percent going to the state transportation department and the rest to local governments.

The sales tax increase would generate an estimated $257.3 million annually. Of that , 20 percent would go to other modes of transportation but most would go into the state's general revenue account to offset the transfer of existing transportation revenues away from several agencies to the transportation department.

Under an amendment approved Wednesday, proceeds from the three-eighths cent sales tax would be gradually directed to transportation -- instead of the general revenue pot -- beginning in July 2005 and concluding in 2010.

Sen. David Klindt said his amendment would mean an additional $195 million a year for the transportation department by the final year of the phase-in.