News

Standing on the corner, watching all the cars go by. We've pressed the little button and nothing seems to happen, but why?

THE QUESTION: How do passenger crossing lights work? You press the button and sometimes the light will turn green right away. More often, there is a wait, sometimes a long one. This puzzles Beryl Young of Vancouver.

THE ANSWER: "The reason for the wait is system co-ordination," writes Chris Neuman from Edmonton's Office of Traffic Safety.

"Traffic signals along a corridor or in an area such as the downtown core are programmed to try and balance the delay that people experience during a trip. Most of this co-ordination favours the direction with the most traffic. "So, for example, Bay Street's lights will be timed to move as much traffic up and down Bay as possible, and people waiting to get onto Bay Street (or go straight across it) may feel as if they're waiting a long time."

However, he says it's not only the traffic lights at intersections that are co-ordinated; pedestrian signals are too. From a traffic-flow perspective, you don't want a pedestrian light to stop traffic at the same time that there is a green light for traffic at some downstream intersection; this interrupts traffic flow.

"So, in most cases, the pedestrian has to wait for the downstream traffic signal to turn red before being allowed to cross." So, if you have the bad luck to arrive at the "wrong" time of the signal cycle, you'll wait up to three minutes before being able to cross.

THE QUESTION: "I've been wondering if the stickers on fruit are biodegradable," writes Brigitte Wiebe of Winnipeg.

THE ANSWER: "I used to leave those stickers on peels I put in my compost bins, but I no longer do," writes Dorothy Carr of Point Edward, Ont. "When you sift the good compost out of the bottom of the containers, those pesky things are still there, as fresh as the day you put them in and totally readable."

FURTHER NOTICE

Gordon Watson of Vancouver has a follow-up to last week's item on what happens to artificial joints when people are cremated. He says his father-in-law died last year and while the family was making arrangements for the cremation, "the funeral director suddenly asked if the deceased had had any joint replacements." The family said yes.

"We were absolutely flabbergasted when he asked if we wanted the artificial joint preserved, since it would be left intact after the cremation. … He quickly added that in general, not many people made such requests, but his firm felt duty-bound to determine the survivors' preferences in this delicate issue."

He also mentioned that one family had had the artificial joint attached to a decorative plaque for display. "We hurriedly assured him that we had no such preferences."

HELP WANTED

Fraser Fulwell of Toronto wants to know if there is a technical difference between a boat and a ship and, if so, what is it?

Judith Stricker of Sidney, B.C., asks what effect, if any, does the fluoride and chlorine in our drinking water, which she puts in the bird-bath, have on birds?

Why do men's and women's shirts unbutton on opposite sides? Susan Fibbiani of Bloomfield, Ont., wants to know.

Send answers (and questions) to wisdom@globeandmail.com. Include your name, location and a daytime phone number.