When a Yellow Light is Too Long

 

Short yellows are a serious problem. In 2001, the Office of the US House Majority Leader issued a report, "The Red Light Running Crisis: Is it Intentional?" explaining in detail the changes the Institute of Transportation Engineers (ITE) made to the commonly used yellow timing formula between 1976 and 1999... Engineers manipulated the standard equation so that it produced yellow times generally shorter by around a second so that, according to the ITE, "enforcement can be used instead" of longer yellows. Prior to the arrival of photo enforcement at intersections, engineers were told to use the equation as a starting point, lengthening the timing until the desired result was achieved.

"When the percent of vehicles that are last through the intersection which enter on red exceeds that which is locally acceptable (many agencies use a value of one to three percent), the yellow interval should be lengthened until the percentage conforms to local standards," the ITE wrote in its 1985 recommended practice...

This practice reflects the proper understanding of traffic engineering. The daily interplay at a given intersection of tens of thousands of drivers varying widely in age and ability driving anything from lightweight sports cars with impressive braking ability to heavily laden 18-wheelers cannot be captured by a mathematical equation. Visibility at the intersections also varies between night and day and pavement conditions can change with the weather. The ITE equation attempts to get the engineer in the ballpark of the best value by producing a recommended minimum, and it is his duty to ensure the theoretical timing is appropriate in practice. The equation is the starting point, not the end point.

http://thenewspaper.com/news/37/3779.asp

Confusing or badly written article

The whole article you refer to develops the reasons why the length of the yellow should start at the formula point as a minimum and then be lengthen as required. It then concludes that "A yellow should only be as long as it needs to be to achieve compliance, in actual practice, with the ultimate goal of reducing the number of accidents to an absolute minimum. There is no benefit in further lengthening yellows simply to satisfy a theoretical assumption.".

I see no development in the article of the reasons it should not be longer...

So...

... the point is that lengthening the yellow phase should be the first step in achieving compliance, before shortening it and going with cameras.

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TomTom built in and Garmin Nuvi 1490T. Eastern Iowa, formerly Southern California "You can check out any time you like...but you can never leave."

What? ?

I can read and understand the first sentence "Short yellows are a serious problem." After that, I would need someone to translate the rest into English! WOW

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Tight lines