ew York State should spend at least $9 billion over the next five years to prevent the deterioration of highways and bridges and reduce traffic congestion in the five boroughs and the surrounding suburbs, according to a New York University study to be released today.

The study echoes the recommendations made in December by an official advisory panel convened by the state transportation commissioner, Joseph H. Boardman, but it is not clear whether either report will have much effect on budget negotiations in Albany.

The new study focused on infrastructure conditions and traffic levels in New York City, on Long Island and in seven counties to the north: Columbia, Dutchess, Orange, Putnam, Rockland, Ulster and Westchester. It was prepared by the Rudin Center for Transportation Policy and Management, part of the Robert F. Wagner Graduate School of Public Service at N.Y.U., and was financed by the General Contractors Association of New York, an industry group that usually advocates more spending on highways and bridges.

In January, Gov. George E. Pataki proposed spending $15.4 billion on projects by the state's Department of Transportation over the next five years, with an additional $2 billion in 2008 and 2009 to come from sources that have not yet been identified. The 14-county downstate region would get $6 billion of the total.

The study concluded that $7.3 billion was needed to maintain existing bridge and road conditions, although congestion would worsen because little money would be available for projects to aid mobility. To prevent deterioration and keep congestion from worsening would require $9 billion, and to improve the infrastructure and reduce congestion to its 1996 level would take $13.7 billion, according to the study's author, Bruce Schaller, a transportation consultant who worked for the city government from 1982 to 1994 before joining the Metropolitan Transportation Authority, where he worked until 1998.

A spokesman for the state's budget division, Michael E. Marr, said the report seemed to be based on earlier spending patterns and did "not reflect the maintenance-first approach we have taken in this budget."

New York City's bridges and roads improved in the mid-1990's but have leveled off in recent years, Mr. Schaller found. On Long Island, the condition of bridges has held steady, but in the Hudson Valley counties, it began worsening in 2000, he said.

Without proper maintenance, bridges can deteriorate precipitously, Mr. Schaller wrote, citing as an example the deadly collapse of the bridge on the Gov. Thomas E. Dewey Thruway over the Schoharie Creek in April 1987. In addition, he said, single-layer asphalt and concrete coatings have been increasingly used for highway repair, saving money in the short term but requiring more frequent repaving.

The study also cited two other studies completed last year. The Texas Transportation Institute, which prepares an annual report on mobility nationwide, found that the New York region was sixth in the nation in the amount of traffic delay experienced during an average car trip, after Los Angeles, San Francisco, Chicago, Washington and Boston.

The New York Metropolitan Transportation Council, a government-sponsored planning agency, concluded that the region has some of the highest freight-shipment costs in the country, with trucking costs double the national average because of congestion. Mr. Schaller wrote that the "congestion problem cannot be 'solved' the way the infrastructure problem can be solved," and that it is hurting economic growth.

"In some ways New York has benefited from other regions' congestion getting worse because of its extensive transit system and the alternatives to using a car," he said in an interview. "However, I don't think that the highway and road systems in the New York area are a net plus in terms of attracting businesses."