The Maryland State Highway Administration lowered the speed limit along a stretch of Rhode Island Avenue, then encouraged the nearby town of Brentwood to request speed cameras there.

The state reduced the speed limit from 35 miles per hour to 25 miles per hour along Rhode Island Avenue near 37th Street in April. Brentwood installed a camera in the newly lowered area in June, and dozens of ticketed drivers began complaining about the change.

The highway agency had approved Brentwood's request for a school zone there with a March 8 letter that ended, "Please feel free to submit an Automated Speed Enforcement application based on the enclosed school zone location."

The SHA's letter was "just stating the obvious" and not soliciting speed camera applications, SHA spokeswoman Sandy Dobson said. The Maryland General Assembly approved speed cameras in 2009 in school and construction zones.

The agency sent a copy of its letter to Baltimore transportation consultant the Traffic Group, according to a copy of the letter obtained by The Washington Examiner.

The consulting group -- which also sells speed camera equipment -- conducted a study of the area and concluded the school zone would be safer with traffic cameras. The group sent its findings to the SHA. The highway agency then authorized Brentwood to install a camera in June.

The agency said the 35-mile-per-hour speed limit was changed because it was found "incorrect" following a routine review of school zones, SHA spokeswoman Kellie Boulware said. In March, the Traffic Group determined 85 percent of drivers cruised that route at 39 to 45 miles per hour. States and local governments base speed limits primarily on how fast the 85th percentile of traffic is driving, according to the Federal Highway Administration. Pedestrian traffic, visibility and accident rates can affect those limits, however.

But changing speed limits has little effect on driver behavior -- even when the speeds are lowered by as much as 20 miles per hour, according to an FHA study.

Brentwood has penciled in roughly $200,000 in speed camera revenue for fiscal 2011, according to the town's $1.4 million budget.

The town has profited from reduced speed limits in the past, according to a February report by Mount Rainier Police Chief Michael Scott.

Brentwood lowered a speed limit on 34th Street westbound to 15 miles per hour -- down from 25 miles per hour -- and installed a camera west of Upsher Street to enforce the new limit, Scott wrote to the Mount Rainier Town Council.

"Brentwood's Chief of Police has informed me that the town intends to install a camera ... to enforce this new 15 MPH speed limit," he wrote.

Brentwood officials did not return phone calls for comment.