M25 silly question

[David Bigcheeseplant]

While driving around the M25 today in an idle moment of thought, I wondered if you stayed in the inside lane all the way round how much further it would be travelling clockwise rather than anticlockwise?

 

David

[David Rickard]

I wouldn't be surprised if it was the same, owing to the fact the M25 isn't a perfect circle, and does wiggle around a lot along the way. Interesting question tho.

[CUTLER2579]

Silly Answer:-

if you did not have a head on collision to prevent you completing the journey it would be exactly the same distance. Its obvious really.If you were on the other carriageway I can't answer cos I aint that clever.

Regards,

[Tony_S]

About 6 times the total lane width (2*PI* motorway width) assuming a circular M25 which is why I said about 6! It isn't really that much of a difference.

[David Bigcheeseplant]

it does not matter if it wiggles it's still a circle the clockwize is a bigger diameter than anticlockwize, there are six lanes and a central resivation so the difference must be the centre line of the the outside clockwize and the centre line of the anti clockwize.

 

It works in the same way as a running track with staggered starts, or a loop of scalelectric where the inside car will allways win.

[Tony_S]

X=difference

R= radius of anticlock route

W= width of carriageways and reservation

 

x = 2PI (R+W) -2PI*R

= 2PI*R + 2PI*W -2PI*R

= 2PI*W

 

Tony

[David Bigcheeseplant]

X=difference

R= radius of anticlock route

W= width of carriageways and reservation

 

x = 2PI (R+W) -2PI*R

= 2PI*R + 2PI*W -2PI*R

= 2PI*W

 

Tony

 

But I want the answer in miles!

[David Bigcheeseplant]

To add another bit in to the thinking it is not all six lanes its up to ten lanes in places.

[David Bigcheeseplant]

Oh, this is good fun!!!!!!!

I believe the difference would be approximately 107.12 metres!

Wanna know how i did it?

Cheers,

John E.

 

Yes please

[34theletterbetweenB&D]

... owing to the fact the M25 isn't a perfect circle, and does wiggle around a lot along the way. ...

All thanks to the careful work of Crowley, so that it makes the symbol Odegra. Good Omens by Gaiman and Pratchett. Read it and laugh until you weep.

[oggy1953]

It works in the same way as a running track with staggered starts, or a loop of scalelectric where the inside car will allways win.

 

 

Not when I'm racing at the Wood Green Scalextric Club on a Tuesday. I normaly come last no matter what lane I'm in !!!!

[Allegheny1600]

Yes please

 

 

No problem.

First we need to know lane width: http://www.ha-research.gov.uk/projects/index.php?id=85 states: 3.65m (sorry - had to do all calcs in metric!)

Next, the width of the central reservation: http://en.wikipedia.org/wiki/Central_reservation This states same as a lane width but i gave it 5m as i'm sure the M25 does change cent res width along it's length!

This gives a total roadway width of 34.2 metres (assuming an "average" of 8 lanes, it really varies between 6 and 12 lanes) http://en.wikipedia.org/wiki/M25_motorway

Then the total length of M25 is 188.3Km divided by Pie: 59 937.2 metres!

Plus HALF the total roadway width of 34.2m (average) Equals: 59 954.2m

(Separately) Minus half total roadway width: 59 920.1m

 

Mulitply both by Pie: 188 351.67m (Clockwise direction!) (Outer ring!).

188 244.55m

 

Difference is: 107.12m!

This is all asuming "averages" - that the sum total of all the curves and bends in the M25 equals a circle! That my quoted websites are accurate etc etc.

I also assumed that the total length of the M25 (given as 188.3Km) is the "average" length!!!!!!

Given the above, we can see that it is actually longer one way than it is the other!!!!

Hope this all makes sense and my apologies for the delay - SWMBO called me for tea!!!!

Cheers,

John E.

[298]

I'm not an M25 basher, so was wondering what the difference would be if it wasn't a perfect circle but you kept to the left hand lane at all times, but moved over where the road layout forced you to in order to continue....? Also, there are sections where the central reservation widens, such as near Abbots Langley and South Mimms. This would literally add meters to the difference....

[Judge Dread]

You say "if you stayed in the inside lane?" It seems to me that that most drivers consider the number one lane as being for lorries only and always use the number two lane, the so called "Centre lane drivers club" according to the police. Even if it means that they cause a holdup and some drivers to have to resort to "undertaking".

Rant over, I'll get back in my box.

[Bernard Lamb]

All rather academic.

You go over the bridge at Dartford going clockwise but through the tunnel going the other way. Well, normally that is.

That b****** it up somewhat.

Bernard

[Glorious NSE]

Ah, but neither the bridge nor the tunnel are part of the M25, hence it isn't a circle...

[Trebor]

Ah, but neither the bridge nor the tunnel are part of the M25, hence it isn't a circle...

 

 

and most of the time its not a motorway either!

[Southernman46]

B*gger the distance - it's about how quick you can drive right around it. Once did this in the middle of the night back in the days when I had energy and sense in inverse proportions. Took about 2 & 1/2 hours if memory serves.

 

I remember reading about a group of fast car junkies that deliberately try (tried)? to do it as quickly as possible in Ferrari's Porshe's etc etc......50 minutes ????

 

Southernman46

[David Bigcheeseplant]

There has to be an answer to this, 107 meters does not seem enough but I don't know why.

 

David

[beast66606]

There has to be an answer to this, 107 meters does not seem enough but I don't know why.

 

David

 

There is a very simple answer Dave - get in the car, drive to a junction and join the motorway, zero the trip meter at a suitable marker, drive one way round and note mileage, then do the same for the other direction, remember you need to pass the marker to get the distance.

 

[Kenton]

While driving around the M25 today in an idle moment of thought,

 

Am I the only one worried that someone driving on the M25 (or any other motorway) can have an idle moment of thought?

 

just a quick thought on the possible carnage caused by not concentrating fully on the traffic madness that is around you should be enough ....

[Pannier Tank]

It seems to me that that most drivers consider the number one lane as being for lorries only and always use the number two lane, the so called "Centre lane drivers club" according to the police. Even if it means that they cause a holdup and some drivers to have to resort to "undertaking".

Rant over, I'll get back in my box.

 

Don't forget the HGV's, one in lane 1 doing 55.5 MPH and another in lane 2 doing 55.9 MPH

[griffgriff]

Not the M25 ... but a mate once told me that driving between Berwick and Edinburgh was one mile shorter than the reverse trip (according to his trip computer at least)

[AndrewC]

There is also junction 5 to consider as the carriageway is down to 2 lanes in each direction where it splits and merges from/with the M26. The clockwise route splits off at the A21 and follows a slightly different route than the anti-clockwise carriageway. Clockwise, its at least 1/4 mile longer at that point. My route (to the Bracknell office) on the M25 from junction 2 to 12 is 0.9 miles longer going clockwise than coming home.

 

 

[Bernard Lamb]

There is a very simple answer Dave - get in the car, drive to a junction and join the motorway, zero the trip meter at a suitable marker, drive one way round and note mileage, then do the same for the other direction, remember you need to pass the marker to get the distance.

 

 

 

Then measure it using a sat nav system. Do it in both directions and check the difference. Then do it on two wheels and check these distances with the ones on four wheels. It should come out at a shorter distance on two wheels. But the difference will probably vary with the direction of travel. Never tried it with the M25 but it does make quite a difference if you go through Milton Keynes.

Bernard