Twenty's plenty

Post date: Apr 28, 2015 7:39:20 PM

I've made a little game to think about stopping a car. This involves hitting a brake button when the shape changes, which then gives you

• • a thinking distance: the distance you before you've reacted to slam on the brakes.

  • a braking distance: this is the distance after hitting the brakes to bring your car to a complete stop (very important for avoiding pedestrians).

  • stopping distance: this is the total distance the car has travelled from when the hazard appeared so is equal to the thinking distance + braking distance.

You can find the game here at https://scratch.mit.edu/projects/59414624/

Above is a screenshot of a run - I was going at 30mph in dry conditions and although it wasn't my fastest reaction time, it's probably quite reflective of someone with average concentration driving around a residential area. The thinking distance was 4.4m but the stopping distance was 17.5m!

In a similar test at 20mph (with similar reaction time) I had a stopping distance of 8m (roughly two car lengths). This nicely shows why in some residential areas in the UK, the speed limit has been reduced to 20mph. By reducing your speed by a third you cut the distance you need to stop in half! Also a lower speed makes it safer in the event of collision too!

The game works for higher speeds too but if you take too long to stop you run out of screen!