By Greg McDonald

WASHINGTON - The Senate approved Thursday a long-awaited change in the nation's highway spending formula as it continued work on a $ 173 billion transportation bill that provides for a $ 26 billion increase in road construction and repair funding over the next six years.

Passage on a voice vote of an amendment co-sponsored by Sens. Phil Gramm, R-Texas, and Robert Byrd, D-W.Va., guarantees that states will get back at least 91 percent of all transportation dollars they send to Washington.

For Texas, which normally gets back about 77 cents on every dollar it pays into the Highway Trust Fund, the Gramm-Byrd formula could mean a boost from about $ 1.2 billion a year in federal transportation dollars to $ 1.8 billion.

The state will also benefit from a $ 450 million program that will help finance construction of so-called NAFTA highway-designated roads, such Interstate 35 and the planned I-69 corridor through Houston.

The Gramm-Byrd measure will also ensure that most of the 4.3 cent-per-gallon tax on gasoline that states contribute to the trust fund will be used for highway and other transportation projects instead of being diverted to other programs.

"This is a victory for common sense," said Gramm, decrying the use of designated highways funds for other purposes while the nation's system of interstates and local highways has steadily deteriorated.

"Texas now has 31,000 miles of substandard roadways, including virtually every major highway in our state. They are in desperate need of repair and upgrading," Gramm said.

Senate leaders also agreed to add $ 5 billion to mass transit funding through the year 2003, which would bring the total amount dedicated to public transportation systems to more than $ 40 billion.

Sen. Kay Bailey Hutchison, R-Texas, hailed the agreement as an important step in providing needed funding for new and proposed rail systems in the state's most populous areas.

"Mass transit must be part of the solution to city congestion," Hutchison said.

The Gramm-Byrd measure was adopted as the underlying funding mechanism for the Intermodal Surface Transportation Efficiency Act, which the Senate hopes to complete work on by the end of next week.

The House is expected to begin work on its version of the highway bill next month. After both chambers pass their own measures, differences will have to be worked out by a conference committee before final legislation can be sent to President Clinton.

The Senate's massive bill has already attracted 200 amendments, including two measures aimed at strengthening the nation's drunken driving laws.

The Senate voted Wednesday to lower the legal blood alcohol level .10 percent to .08 percent, and on Thursday approved an amendment that would ban the possession of open alcoholic beverage containers in operating vehicles.

The open-container measure, approved by a vote of 52-47, would affect 27 states, including Texas. It would also end the practice in five states - Alabama, Mississippi, Louisiana, Wyoming and Montana - of allowing drivers to drink as long as they stay within the current legal limit of .10.

States choosing not to comply with the open-container ban would lose 5 percent of their federal transportation dollars beginning in 2002 and 10 percent each year after that.

"In 22 states, it is legal for passengers in a car to be drinking and in five states it is perfectly legal for the driver of a vehicle to have one hand on the steering wheel and the other wrapped around an open bottle of whiskey," said Sen. Byron Dorgan, D-N.D., who sponsored the measure.

"This legislation would ensure that in every state, neither the driver of a vehicle, nor any of the passengers, would be legally permitted to drink in the car," Dorgan added.

The Dorgan amendment would not apply to passengers in vehicles designed to transport more than 10 passengers, such as buses or large limousines.

The Senate began debate Thursday as well on a contentious amendment to the highway bill offered by Sen. Mitch McConnell that would repeal the federal Enterprise Disadvantaged Program, which is designed to help women- and minority-owned small businesses compete for work on transportation projects.

McConnell said the program was little more than "quota-based system" that he described as "unfair, unconstitutional and just plain un-American."

Opponents of the measure called it an attack on affirmative action programs that threatens to role back the the gains that have been made by small women- and minority-owned businesses trying to gain entry into a transportation industry dominated by big companies.

"This is a fundamental challenge to an effort that this country has undertaken to make real the promises . . . of fairness and equality," Sen. John Kerry, D-Mass., said of the amendment.