Reports of assaults on bus drivers have increased by more than half again in the first seven months of this year, Metro officials said yesterday, as police continued to investigate two attacks in the past week.

By the end of July, 44 drivers had been assaulted, compared with 28 over the same span last year. The overwhelming number of attacks took place in the District, officials said.

Transit Police Chief Polly L. Hanson attributed the increase in part to better reporting within the agency. Nonetheless, concern for driver safety has heightened in the past week after incidents in which one driver was sexually assaulted and another suffered a broken nose.

On Friday, a female bus driver was sexually assaulted in the Centreville area by a rider who drew her to the back of the bus after she had stopped at the end of a route. Hanson said the passenger might have thrown something to get her attention. She said no arrests have been made.

Another driver suffered a broken nose Monday morning at Mount Olivet Road and West Virginia Avenue NE after asking a passenger to pay his fare. The passenger responded by hitting the driver and fleeing.

Metro officials described bus drivers as having the hardest jobs in the system, at times traveling alone in unsafe neighborhoods, dealing with people who don't want to pay fares and children who hurl rocks and snowballs at their vehicles. And they are confronting all of this while trying to safely steer their vehicles through traffic.

Bus drivers are also keenly aware that the last victim of convicted snipers John Allen Muhammad and Lee Boyd Malvo was a Montgomery County operator standing in the doorway of his bus.

Because of the dangers and hassles, many drivers aspire to be promoted to rail operator, where incidents, big or small, are rare, officials said. "Rail operators don't get assaulted," Hanson said.

Metro officials have focused on bus driver safety for more than a year, after residents of a Southeast Washington neighborhood complained to the transit agency that they were tired of having objects thrown at buses that have included rocks, bricks, chunks of concrete, snowballs and a bowling ball.

Officials responded by encouraging drivers to vigorously report all incidents, reach out to the communities they work in and consider wearing goggles in case of shattered glass.

Metro officials said their efforts to crack down on the assaults and vandalism are hampered by a lack of funds. They said security cameras would cut down on crime, or at least increase arrests, but the costs are prohibitive. There are cameras on 100 of the system's 1,450 buses, with 120 more on the way, said Jack Requa, Metro's chief operating officer for buses. Outfitting the rest would cost an additional $8.6 million, Requa said.

Hanson said that youngsters launching rocks and other projectiles at buses are the biggest problem, and she blames the parents. "The thing that's disturbing to me is, in many cases, these are neighborhood kids," Hanson said. "I would really like to see the community more outraged at their own children."

Union officials who represent Metro bus drivers did not return calls for comment yesterday.

Operators of suburban buses also said that although rock- and snowball-throwing are problems for them, assaults are rare.

"People try to ding us for not paying fares," said Al Harf, executive director of the Potomac and Rappahannock Transportation Commission, which operates OmniRide. "We have delinquents and others that might throw things at a bus."

Transit Police Chief Polly L. Hanson said attacks on rail operators are rare. Thus, officials say, many bus drivers aspire to those safer positions.