The first traffic control device appeared near the British House of Parliament at the intersection of
George and Bridge Streets. The device was made in response to the desire by a Select
Committee to use railway signals on highways. The device had lights and it used arms which
extended outwards. It was operated manually by a police officer. The signal was 22 feet high and
crowned with a gas light. The light was called semaphore and had arms that would extend
horizontally that commanded drivers to "Stop" and then the arms would lower to a 45 degrees
angle to tell drivers to proceed with "Caution". At night a red light would command "Stop" and a
green light wouldmean use "Caution".The man behind this new and different invention was John
Peake Knight a railroad engineer. The main reason for the traffic light was that there was an
overflow of horse-drawn traffic over Westminster Bridge which forced thousands of pedestrians to
walk next to the house of Parliament. But Knight's invention was not to last long. After only a
month of use the device exploded and injured the police officer who was operating the light. In the
first two decades of the 20th century semaphore traffic signals, like the one in London, were in use
all over the United States with each state having its own design of the device. One good example
was from Toledo, Ohio in 1908. The words "Stop" and "Go" were in white on a green background
and the lights had red and green lenses illuminated by kerosene lamps for night travelers and the
arms where eight feet above ground. Controlled by a traffic officer who would blow a whistle
before changing the commands on this signal to help alert travelers of the change, the design was
also used in Philadelphia and Detroit. The example in Ohio was the first time America tried to use
a more visible form of traffic control that evolved the use of semaphore. The device that was used
in Ohio was designed based on the use of railroad signals.
1. What was the main purpose of making the first traffic control device?
……………………………………………………………………………………………………………
2. What was the light operated manually by a police officer called?
………………………………………………………………………………………………………………
3. Why wasn't John Peake Knight's invention to last long?
…………………………………………………………………………………………………………
4. How tall were the arms of the traffic lights used in Ohio in 1908?
………………………………………………………………………………………………………………
5. The Westminster Bridge is in .
………………………………………………………………………………
Loga
Sinh Học lớp 12
