Alexandria Circuit Court Judge Wiley R. Wright Jr. refused yesterday to order the city of Alexandria to open two chain-link fences it has erected across two streets leading to Fairfax County.

The judge held that county lawyers had failed to prove that the two fences in the Dowden Terrace neighborhood near Baileys Crossroads had caused the county an immediate hardship.

The county sued Alexandria shortly after it erected the five-foot-tall barricades on North Chambliss and North Stevens Streets June 12 in an effort to stop commuters from using the streets to reached Shirley Highway.

The county claimed that the fencesposed a hazard to fire protection in the area and that the city had no right to erect them.

Residents of the Alexandria side of Dowden Terrace have complained of speeding cars and traffic in their neighborhoods, and the fear it is only a matter of time before a child is hit by a car.

Fairfax County Fire Chief George Alexander testified yesterday that the barricades have increased the time firemen require to respond to an alarm there by as much as one minute. Dowden Terrace residents in Alexandria are covered by Fairfax fire and rescue services under an agreement between the two jurisdictions.

City lawyers argued in response that Fairfax County fire and rescue units could still reach homes in the area within four minutes, their standard response time for calls elsewhere.

Judge Wright set trial of the case for late August.