Fairfax City Council members agreed informally last week to build another lane on Rte. 123 between Kenmore Drive and Warwick Avenue, apparently abandoning a plan to widen the highway to four lanes.

Some council members backed a plan last month to put an $8 million road bond referendum on May's ballot to pay for the four-lane widening.

Although they did not vote formally at the Jan. 6 work session, council members said they had reached a consensus to put the $1 million project in this year's capital improvement program, a list of road construction, school renovation and other work that the city plans.

The council did not work out exactly how to pay for the project, whether through increasing the real estate tax, cutting other programs or using money raised through a restaurant tax or another mechanism.

"There's not a lot of groundswell support out there for another bond issue," said council member Allen C. Griffith, explaining why he would no longer push for a bond referendum this spring. Griffith was one of the strongest supporters of a $15 million bond referendum the council placed on November's ballot for major improvements along the highway. The referendum lost by a 3-to-1 ratio.

Rte. 123 (Chain Bridge Road) is one of Northern Virginia's few main north-south highways and is a popular commuter route for drivers going from Burke or Fairfax Station to the county government center, Tysons Corner, Reston and the Dulles corridor. Rush hour traffic backups are chronic on the road, which narrows to two lanes at several points in the city.

John Mason, the only council member to vote against putting last fall's referendum on the ballot, has been advocating the third-lane alternative for Rte. 123 for months. It would involve adding a 16-foot-wide middle lane to be used only for left turns and would be interrupted by painted medians. City officials estimate that it would cost $920,000 and be finished in a year.

The plan would not affect Rte. 123 at tree-lined Rust Curve or in the rest of the city.

The proposal received only lukewarm support from Griffith and other council members who had supported the November referendum and who generally favor more ambitious approaches to improving traffic on Rte. 123. "I'm not sure this solution does not encourage what we're trying to avoid: pump more cars off the highway onto the residential neighborhood," Griffith said.

"I was careful not to specify where the left turns might occur," said Mason, adding that this could be worked out later.

Financing also could be a difficult question because the projects City Manager Edward A. Wyatt included in his draft capital improvement program have already put the program $350,000 over budget for the coming year.

His draft proposal includes projects costing $29.3 million during the next five years. The most expensive project, an $11.5 million plan to expand the city's water treatment plant in Loudoun County, would be paid for by a city bond referendum and later repaid by Loudoun residents who use city water. But other projects, including $1.8 million for school air conditioning and $1 million for improving Roberts Road, would have to come out of general city revenue.

The Planning Commission has recommended changes in the capital improvement plan that would add an estimated $350,000 to next year's deficit, but savings in later years would balance the budget over five years, by city estimates.

Among the changes the commission has recommended is starting the work on Roberts Road this year instead of next year.

Mayor George T. Snyder Jr., who opposed the November referendum but said he supported a third turn lane for Rte. 123, has proposed using money from the city's restaurant tax to pay for the improvements.

In other business, the council deferred discussing the Roberts Road improvements until after affected communities can meet. Some council members say they believe that improvements are necessary there because of rapidly increasing rush hour traffic, but some residents have protested that improvements might damage private property and increase traffic speeds.