In traffic, he saw the light; Inventor: Charles Adler Jr. ended one source of frustration for the motorist with his sound-actuated signals.

The next time you're sitting at the traffic light at Falls Road and Northern Parkway, stealing a quick moment to scan newspaper headlines, tune the radio, adjust a necktie or run a comb through your hair, you can thank Baltimorean Charles Adler Jr., who invented the traffic-actuated signal and installed it at the intersection in 1928.

Adler, a prolific inventor throughout his long life, invented the sound-operated light because, "I was tired of being stopped by timed signals for no reason at all," he told The Evening Sun in a 1977 interview. "I thought it was outrageous that a human being should be subject to a clock."


Before Adler's invention was in place, all traffic signals were time operated.

"The whole principle of actuating signals by sound originated with me," he told the newspaper.


In those days, the intersection of Falls Road and then-Belvedere Avenue was still slightly rural and its agrarian characteristics created some interesting problems for the new signal.

"After it was installed," Adler told a reporter, "it blinked like a dime-store Christmas tree until we discovered that cows were activating it every time they mooed."

Another time, a farmer whose vehicle had no horn sat and sat at the unblinking red light.

Adler said, "He would have been there still had he not bellowed, 'Change, gol dern ye!' And it changed immediately."

Today, traffic lights still work on the principles that Adler established more than 70 years ago. A car rolls up, breaks the beam from a sonic detector overhead, and the signal flashes green, and then reverts to red.

The holder of more than 60 patents, Adler got his first patent in 1914 when he developed and installed an electric brake on his father's Packard touring car. He later donated most of his patents to the state and federal governments.

Born and reared on Madison Avenue in Baltimore, the son of a physician, Adler graduated from Park School and studied for two years at Johns Hopkins University before dropping out and going to work for the Maryland and Pennsylvania Railroad as a telegrapher and assistant station agent in Towson in 1919.

Adler's traffic signal was born out of an actuated signal that he invented for the railroad, which was known locally as the "Ma & Pa."


The signals protected the railroad's numerous grade crossings on its 90-mile route between Baltimore and York, Pa.

"In the absence of railroad traffic the signal showed nothing to the highway but it was showing stop to the railroad," he said.

"When a train approached, a track circuit actuated the signal because it was fail-safe -- and flashed red to the highway."

Called the Adler flashing relay, the signal was later adopted for use by more than 40 railroads nationwide.

Adler, who remained a signal consultant to the Ma and Pa until 1957, later moved his laboratory to a room in the Baltimore and Ohio's Mount Royal Station.

Not all of his inventions were earthbound, however. By the late 1930s, an interest in aviation safety caused him to earn his pilot's license.


By the early 1940s, Adler had invented the first of a series of flashing or revolving red lights that were installed on the wings and tails of airplanes. The lights could not be confused with stars overhead or ground lights.

His "double-reflector aircraft anti-collision strobe light," which he invented in the early 1970s, was installed in two places on the airplane's tail and emitted flashes of piercing white light that was visible day or night.

He also developed special lenses for the color-blind and a double-filament bulb for warning signals that burned out in sections, allowing replacement of the bulb before it stopped operating.

Some of his oddball inventions that didn't catch on included a horn for automobiles, the Space-ometer -- an automobile speedometer that showed the number of car lengths the driver should keep between his car and the car ahead -- and the Beaconbulb, an application of the aircraft light that would be used as a daytime running light on autos.

An inveterate railroad fan, Adler had four apartments in the Sutton Place Apartments, which overlook the mainline tracks of the B & O as they plunge into the Mount Royal train shed.

"I get a kick out of it," he told the newspaper.


From his apartment -- The Evening Sun said it "looks like a branch of the Smithsonian Institution that is crammed with books, bottles, jars, photographs, miniature trains, models of his inventions, testimonies of his inventiveness" -- Adler found time to write humor pieces for the New York Times and the Reader's Digest.

Other interests included collecting automobiles. Adler had a rare 1955 Lincoln Mark II, a 1972 Corvette and a 1952 MG TD. He drove the cars twice a week. "I've had the Mark II up to a 100," he boasted to the newspaper.

He was a man who eschewed all physical activity.

"He hated sports," his daughter, Amalie Adler Ascher, told The Evening Sun in an interview. "When the urge to exercise came, he would lie down until it passed."

In 1964, Adler, a member of the old Friendship Airport Board, first proposed a rail station at what is today Baltimore-Washington International Airport, providing an important link between ground and air transportation.

His death on Oct. 23, 1980, came only hours before he planned to attend the station's dedication at its location off Route 170.