Cesar Martinez had just made a wrong turn due to a dying GPS when he noticed a errant Wallingford-Swarthnmore school bus careening into bushes, knocking down street signs and traveling across suburban front lawns.

As the back of the bus swung about wildly, "I thought it was going to flip over," Martinez recalled. He immediately called 911.

With the help of his older sister, Yolanda Martinez, calling out the street names, Martinez, 39, of Norristown, stuck with the bus and was able to keep police abreast.

Police pulled over the driver near Yale Avenue and Chester Road, where the bus stopped on the sidewalk. One passenger was aboard, a 16-year-old boy. He was not injured.

The driver, Christine Rogers, 39, of Brookhaven, was charged with driving under the influence and other related crimes in the Monday incident, according to Brian Craig, Swarthmore chief of police.

"The kid was really shaken up," said Craig. "The officer spent a lot of time telling him it was OK to get off the bus."

Wallingford-Swarthmore School District officials declined to comment.

Craig said the arresting officer detected a strong odor of alcohol. He said an empty vodka bottle and a water bottle that police suspect was filled with alcohol were found in Roger's purse next to the driver seat.

"Don't do this to me," Rogers allegedly told police when asked how much she had to drink, according to court documents.

Police field-tested Rogers, who had a preliminary blood-alcohol level of 0.374, according to Craig, which is more than four times the legal limit of .08. He said officers at the scene transported her to an area hospital, where she was admitted.

Martinez, a warehouse operator for the Philadelphia Coca-Cola Bottling Company, ended up being late for work but said it was worth the trouble.

Craig said Martinez had to travel "quite a bit" to keep track of the bus.

"By the time the bus stopped, he had no idea where he was," Craig said.

Contact staff writer Mari A. Schaefer at 610-892-9149 or mschaefer@phillynews.com.