This article said 35mph. Other articles have suggested it was a 45mph zone.

On Google Streetview, you can see that the road changes from 35mph to 45mph at the underpass before the site of the accident.

"The vehicle was doing about 40 miles per hour on a street with a 45 m.p.h. speed limit when it struck Ms. Herzberg, who was walking her bicycle across the street, according to the Tempe police"

> "The vehicle was doing about 40 miles per hour on a street with a 45 m.p.h. speed limit when it struck Ms. Herzberg, who was walking her bicycle across the street, according to the Tempe police"

According to the article page that you are commenting, "The speed limit where the accident occurred is 35 mph, police spokeswoman Lily Duran said."

Even so, defensive driving is more than simply driving the speed limit. Also from this article, "... the lack of braking or swerving whatsoever is alarming and suggests that the system never anticipated the collision."

Might be an error? If you travel that road on street view, you see a sign for 30mph, the 35mph before the bridge over water, then 45mph at the underpass. The sign is mounted above the road, on the underpass itself.

Of course, something might have changed since street view went through.

It was a 35 mph zone.

Are you sure? Per Street View, there's a 45 mph sign where the road goes under the underpass, prior to the site of the accident. Unless that's since changed, of course.

Another possibility: the car was relying on outdated speed limit data. Which is another potential failing of such systems.