Over on the comments to this post, there’s a discussion about the merits of lowering the speed limit to 25 MPH in Newton when drivers are comfortable — on nearly all roads — going significantly faster. It’s a fair question.
One answer is easy: while it is comfortable — and even, likely, safe — for the driver to go faster, it’s definitively less safe for pedestrians on the road. As speeds go up — even within the range of what folks are comfortable driving on Newton roads — the risk of death and serious injury goes up dramatically. Just look at the chart, from a Federal Highway Administration document. The figures are for risk of death and serious injury from a crash. The numbers are even more dramatic when you consider that lower speed increase the likelihood of avoiding a crash in the first place.
If all we cared about were drivers and passengers in cars, lowering the speed limit would make little sense. But, we also care about pedestrians and cyclists. Not only do we care about their safety, we care about their comfort. If our roads have slower traffic, cyclists and pedestrians will feel safer (because they are) and bike and walk more.
And if, after a year or two there is no statistical difference in the number or severity of accidents involving pedestrians or cyclists in Newton, then I am sure the ever self effacing City Council will see the uselessness of this decision and raise the limit back to 30 mph. Right after they lift the ban on leaf blowers.
There are about 70 pedestrians hit by drivers a year in Newton with all type of conditions and varying speeds. So it would take YEARS for there to be enough data to evaluate and be statistically confident. But the much more important point is there is nothing unique about Newton that would make the laws of physics different here than elsewhere. There is plenty of evidence that shows quite clearly that the higher a vehicle is traveling when it hits a person, the more serious the injury will be and the increased chance of death. Add to that the faster a car is driving the less the driver can see (cone of vision) and the longer it takes to stop, so the more likely crashes are to occur. So 25 mph is a great idea. Now to design our roads so people DRIVE 25, Keep People Alive!
One more point I will stress is that getting vehicles to drive slower will also be safer for vehicles. There will be less single vehicle crashes as well as vehicle vs vehicle crashes.