Holy cow, I wrote a book!
It sounds like the set-up to an old joke, but it's not.
It's just one of the random bits of trivia that I wondered about.
For intersections with both high pedestrian and high vehicle volumes,
I was able to find the Federal Highway Administration recommendation,
which is to give
pedestrians a head start to allow them to cross one lane of
traffic before vehicles are given a green light,
and the formula they use for determining how much time to allow is
2.8 feet per second.
In the city of Bellevue,
planners assume a pedestrian speed of four feet per second.
At Microsoft campus, there is
one dedicated pedestrian crossing,
and the planners who designed the crossing came up with a clever
hack to reduce the amount of time that traffic is stopped while
still adhering to the four-feet-per-second rule.
As you can see from the photo, there is an island in the road.
Traffic is stopped long enough to allow a four-feet-per-second pedestrian
to reach the center island.
The pedestrian can then hit a crossing control button on
the island to get a second chunk of time to complete the crossing.
On the other hand, a faster pedestrian can complete the entire
crossing within one cycle and the center crossing control is not needed.
Before the pedestrian crossing was installed there,
you would often seen Microsoft employees jaywalking at that location
by playing a game of real-life
You'd be driving along and catch a head peeping out of the trees
on the median and have a brief moment of panic as you realized
you were travelling too fast to stop in time if the person
decided to take that moment to resume their crossing.
Signs and warnings didn't stop people from jaywalking,
so the traffic planners installed an official crossing,
for which I am thankful.
Now I no longer panic when I drive past that area.
(For completeness, here is
the Washington State Crosswalk Law in pictures.)