This week a driver in Brooklyn, New York, is luck to be alive after driving through a plywood barrier along Coney Island Avenue in Midwood, and down 40 feet into a construction pit. Unfortunately, the unidentified driver first struck a bicyclist, then collided with several cars, before crashing through the barrier.

Witnesses said the woman was driving a blue Toyota Highlander north on Coney Island Avenue near Avenue L before 10 a.m. when she struck a bicyclist traveling south on the wrong side of the road. In swerving to try to avoid the bicycle, the woman ended up hitting a delivery truck, a second delivery van and then a parked Nissan Maxima, witnesses said. Then the S.U.V. blasted through a protective plywood barrier and into a hole, about 40 feet deep.

“The car turned over; it was a loud noise, and everyone turned to look,” said Omar Porcayo, 21, who works at Pomegranate, a kosher supermarket across the street. “I ran over and saw two people. I saw construction workers pulling her out of the car. I was surprised they didn’t get hit, too. Everyone was amazed.”

In most cases construction sites are clearly marked, as this one certainly was, but in come instances drivers completely lose control of their vehicles, making signage meaningless. This is a big part of the reason why defensive drivers always travel at a safe speed, especially in congested areas with limited clearance on either side.

In nearly all fatal vehicle crashes, despite emphasis placed on distracted and drunk driving, speed is a factor. There is no denying that the faster a vehicle goes the more difficult it is to control, and the more difficult it is to anticipate the hazards a driver might encounter on the road ahead.

Posted speed limits are there for a reason. Although this New York driver was lucky this time (and so was everyone she hit and nearly hit, including the construction workers in the pit where she landed) next time it might be an entirely different story.