Origin
Before the mid 1980s, Pittsburgh had a non-standard traffic light sequence. The green light would become simultaneous green/yellow, then just yellow, and finally red. While some believe this sequence reduced the chances of cross-traffic running the red light immediately before the anticipated green, and thus encouraged early left turning, this practice is also observed in other regions with no history of simultaneous green and yellow. Some large intersections have four-way red for several seconds as a safety buffer, providing an opportunity for an illegal and unsafe left turn after cross-traffic has physically stopped but before the green light gives legal right of way.
Read more about this topic: Pittsburgh Left
Famous quotes containing the word origin:
“Someone had literally run to earth
In an old cellar hole in a byroad
The origin of all the family there.
Thence they were sprung, so numerous a tribe
That now not all the houses left in town
Made shift to shelter them without the help
Of here and there a tent in grove and orchard.”
—Robert Frost (1874–1963)
“Good resolutions are useless attempts to interfere with scientific laws. Their origin is pure vanity. Their result is absolutely nil. They give us, now and then, some of those luxurious sterile emotions that have a certain charm for the weak.... They are simply cheques that men draw on a bank where they have no account.”
—Oscar Wilde (1854–1900)
“Each structure and institution here was so primitive that you could at once refer it to its source; but our buildings commonly suggest neither their origin nor their purpose.”
—Henry David Thoreau (1817–1862)