WASHINGTON – This fall, Dave Salovesh, who’s 10-year-old daughter uses the Pennsylvania Avenue bike lane to get to school, spent a morning videotaping drivers.

“I counted 25 U-turns in that half hour,” Salovesh tells WTOP – all of them across the same bike lane where his daughter treks.

When he asked drivers why they made the U-turns, they said “they didn’t know that it was illegal despite the signs that are right there. That it’s inconvenient to go out of their way to go around the block.”

Pennsylvania Avenue NW, with its unique center bike lane, has seen 14 accidents involving bicycles between 2010 and 2011. Of those, 11 involved vehicles making U-turns, according to the District Department of Transportation.

And similar crashes have occurred along the same stretch of road this year as well, spurring D.C. Mayor Vincent Gray to make an emergency rule change.

Beginning Dec. 1, U-turns will be prohibited at all times across bike lanes, regardless if a biker is present or not, DDOT says.

“The ambiguity has been whether it’s permitted to do it mid-block,” said John Lisle, spokesman for DDOT, Wednesday.

Violating the revised rule will cost drivers $100.

“This is an effort to ensure the safety of our increasing numbers of cyclists in the District by closing a regulatory gap,” Gray said in a statement. “This action is in line with my efforts not only to protect public safety, but also to encourage a greener, healthier, more sustainable District.

WTOP’s Kate Ryan contributed to this report. Follow @Kate and@WTOP on Twitter.

(Copyright 2012 by WTOP. All Rights Reserved.)