A、They are falling out of use in the US. B、They tend to be ignored by drivers within months. C、They are applicable only on broad

Believe it or not, optical illusions can cut highway crashes. Japan is a case in point. It has reduced automobile crashes on some roads by nearly 75 percent using a simple optical illusion. Now the American Association Foundation for Traffic Safety in Washington D.C. is planning to repeat Japan’s success. Excessive speed plays a major role in as much as one fifth of all fatal traffic accidents, according to the foundation. To help reduce those accidents, the foundation will conduct its tests in areas where speed- related hazards are the greatest--curves, exit slopes, traffic circles, and bridges. Some studies suggest that straight, horizontal bars painted across the roads can initially cut the average speed of drivers in half. However, traffic often returns to full speed within months as drivers become used to seeing the painted bar. V shapes, scientists say, not only give drivers the impression that they are driving faster than they really are, but also make a lane appear to be narrower. The result is a longer lasting reduction in highway speed and the number of traffic accidents.