Ever notice how the traffic lights in Chicago switch from yellow to red quicker than in other cities? That's because the city changed the formula.
FiveThirtyEight reports the formula — yellow change time = 1 + (1.47 * Approach Speed) / (2 * Deceleration Rate) — was altered to increase the chances of a driver running a red, an act that would then be caught by the city's red-light cameras, thus leading to a fine for the driver.
The formula used in Chicago is the one prescribed by the American Association of State Highway and Transportation Officials, which sets the deceleration rate at 11.2 feet/second over the standard formula's 10 feet/second. The city also calculates yellow intervals by the posted speed limit, instead of the Federal Highway Association's 85th percentile speed of real drivers, with the option to add 5 mph to the speed-limit yellow interval, as well.
The yellow interval — and its tie to the red-light cameras — have been a factor in Mayor Rahm Emanuel's fight for another term in office, which has since entered the runoff phase after his campaign failed to gain an outright majority Tuesday. Emanuel's support for the cameras runs in opposition of the city's residents, 66 percent of whom believe the technology isn't helping traffic safety in the least.
The post Chicago's Yellow Light Intervals Generating More Fines appeared first on The Truth About Cars.
from The Truth About Cars http://ift.tt/Jh8LjA
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