Originally Posted by
JeffB502
They're painted as no passing zones because you don't know if a high speed vehicle is coming from the other side of the hill. See attached picture for a rudimentary drawing of what I'm thinking. Red squares are cyclists stopped at various locations...blue squares are cars, blue lines are sight lines. Notice how cars approaching from both sides can see the cyclist if he's stopped at the highest point, but the cars approaching from the right wouldn't see the cyclist stopped at the bottom of the hill until they crest the hill. Of course we're assuming the road is straight which is kind of unusual for a road with any kind of sight impeding hills. Am I missing something?
Yes, you're missing a few things --
Most of a driver's attention is focused on nearby traffic or hazards no more than 5-10 seconds away. When climbing a hill, they can only see until the curve of the hill drops out of sight, which can be an extremely short distance in some cases, giving less reaction time than the often-recommended two-second rule.
Going literally by your drawing, a car at the red square on the left traveling left-to-right would not be able to see the red cyclist at the top of the hill; even worse would be the middle blue square climbing towards the right square. But, your drawing is flawed because it's not to scale. Either those squares would be representing cars and cyclists tens of feet tall or the hills are severe enough to be a roller coaster in a cheap amusement park.
The next time you're in a car on a hilly road (and where I grew up, arrow-straight roads with lots of hills were common in the countryside), count how long you can see a roadside object as it appears over the crest of a hill versus how long you can see one in the valley of the other side.
However, the BEST place to stop is on the uphill side, high enough to give even more visible distance from the crest of the previous hill, but low enough so that you're not out of sight of traffic climbing towards you. In your drawing, that would be somewhere halfway between the blue squares on the right.