Can I overtake?
Discussion
There have been a number of posts regarding overtaking and whether or not to break the 60mph NSL when doing so. VH, as expected, holds the view that no speed limit should be exceeded when overtaking and if breaking the speed limit would be necessary in order to generate a ‘safe’ overtake then that overtake should not be carried out. The IAM ‘manual’ also states that speed limits must not be broken.
Please consider the following: -
I wish to overtake a car travelling at 50mph on a single-carriageway NSL road. Ideal circumstances in that as I approach at 60mph there is an opportunity to pass. So no acceleration required!
I ‘pull out’ when 3 car lengths behind and pull back in when the rear of my car is 3 car lengths past the overtaken car. Total ‘gain’ on overtaken car is 8 car lengths. Allow 15 feet for car length so distance travelled = 120 feet. At a speed differential of 10mph that is 8.2 seconds. At 60mph in 8.2 seconds I will have travelled 722 feet = 220 metres.
If a car is approaching at 60mph then I will need double that distance plus, say, a 2 second safety margin so I am back on my side of the road before the approaching car reaches me and without frightening the driver. So total distance to approaching car for a safe overtake is now 1602 feet = 488 metres = well over ¼ mile.
Even if the car I am overtaking is travelling at 40mph, in the face of oncoming traffic, I will still need 274 metres for a safe overtake.
Explains why I now seem to rarely overtake on single carriageway roads.
Other drivers seem to shorten the distance needed for the overtake by one of, or a combination of, four methods
a) break the speed limit
b) Start very close to the back of the car being overtaken
c) pull in sharply in front of the car being overtaken
d) reduce separation between their vehicle and approaching vehicle on completion of overtake.
All these comprise safety – with the possible exception of a) that just risks a fine & points!
I now wait for my maths and assumptions to be torn apart!
Please consider the following: -
I wish to overtake a car travelling at 50mph on a single-carriageway NSL road. Ideal circumstances in that as I approach at 60mph there is an opportunity to pass. So no acceleration required!
I ‘pull out’ when 3 car lengths behind and pull back in when the rear of my car is 3 car lengths past the overtaken car. Total ‘gain’ on overtaken car is 8 car lengths. Allow 15 feet for car length so distance travelled = 120 feet. At a speed differential of 10mph that is 8.2 seconds. At 60mph in 8.2 seconds I will have travelled 722 feet = 220 metres.
If a car is approaching at 60mph then I will need double that distance plus, say, a 2 second safety margin so I am back on my side of the road before the approaching car reaches me and without frightening the driver. So total distance to approaching car for a safe overtake is now 1602 feet = 488 metres = well over ¼ mile.
Even if the car I am overtaking is travelling at 40mph, in the face of oncoming traffic, I will still need 274 metres for a safe overtake.
Explains why I now seem to rarely overtake on single carriageway roads.
Other drivers seem to shorten the distance needed for the overtake by one of, or a combination of, four methods
a) break the speed limit
b) Start very close to the back of the car being overtaken
c) pull in sharply in front of the car being overtaken
d) reduce separation between their vehicle and approaching vehicle on completion of overtake.
All these comprise safety – with the possible exception of a) that just risks a fine & points!
I now wait for my maths and assumptions to be torn apart!
Gassing Station | Advanced Driving | Top of Page | What's New | My Stuff