Undertaking....
Discussion
Bweber said:
What is the legality of exiting a motorway blocked with standing traffic at a services and rejoining ahead of where you would have been? I cannot see anything illegal in this at all even though I would never do it. On the one hand, exiting and rejoining a motorway adds unnecessary risk but on the other hand, you could simply argue that you exited because you were short of fuel and changed your mind when you saw the price. Exit / rejoin has the same effect as a roundabout slingshot - using the appropriate lanes in compliance with regulation but gaining an advantage over where you were supposed to have been.
That's an interesting one- there are similar cases where you can pass a long motorway queue in lanes 2 and 3 by using the dedicated exit lane to exit at a junction and rejoin afterwards. As far as I can see that is avoiding the hold up caused by the reduction of straight ahead lanes from 3 to 2, and gives the junction hopper an advantage without inconveniencing anyone. But you wouldn't want everyone doing it as it would seize the junction up- so is it legal?SydneyBridge said:
Seems to be a million times worse on 4 lane motorways, with no hard shoulder. Some people absolutely refuse to use lane 1 ever and some people get in lane 3 and cruise along happily irrelent of traffic, or lack of, in other lanes. They also do not think they are doing anything wrong
This I noticed on a 450-mile round trip (utilising the M1, M25 and a bit of the M4) last week. There were lorries in lane 3 snail racing.Also, slight aside but in place of the hard shoulder were lay-bys which I thought was pretty edgy stuff.
The advantage of a hard shoulder is you can ease onto it and slow down. You can then use it as a runway to bring your vehicle up to speed before rejoining lane 1. I wouldn't want to have to use a lay-by as a launch pad.
Then again on the way back there was a broken down car and in advance of it the speed limit was reduced to 40, so perhaps that's how the lay-by system works.
mko9 said:
Why bother to change lanes four time when you can continue on unimpeded in the lane you are in?
This rings true for me.Again, long round trip last week. For the most part I did 60.
Something I noticed: every time I was in lane 1 and would encounter a car bumbling along obliviously in lane 2, I would bring my car level with that car and it would basically wake the driver up out of their day dream, and they would literally floor it and speed up to 70. This happened at least 3 times.
I also totallyaccidentally cut up a car in lane 2 when I was came in from lane 3 too soon, when that car could have been in lane 1 as there was a lengthy stretch with nothing going on in lane 1.
Again, it must have caused the driver to wake up as he then suddenly accelerated...yet he stayed in lane 2 even though by that point I was doing 70 in lane 1.
captain.scarlet said:
This I noticed on a 450-mile round trip (utilising the M1, M25 and a bit of the M4) last week. There were lorries in lane 3 snail racing.
Also, slight aside but in place of the hard shoulder were lay-bys which I thought was pretty edgy stuff.
The advantage of a hard shoulder is you can ease onto it and slow down. You can then use it as a runway to bring your vehicle up to speed before rejoining lane 1. I wouldn't want to have to use a lay-by as a launch pad.
Then again on the way back there was a broken down car and in advance of it the speed limit was reduced to 40, so perhaps that's how the lay-by system works.
Are we sure we are in the advanced driving forum? This feels a bit like the I don't know enough basics to have passed my test yet forum Also, slight aside but in place of the hard shoulder were lay-bys which I thought was pretty edgy stuff.
The advantage of a hard shoulder is you can ease onto it and slow down. You can then use it as a runway to bring your vehicle up to speed before rejoining lane 1. I wouldn't want to have to use a lay-by as a launch pad.
Then again on the way back there was a broken down car and in advance of it the speed limit was reduced to 40, so perhaps that's how the lay-by system works.
Graveworm said:
Full circle is coming back the same way, as you describe it's not going around again to take the first exit. There is a correct lane for the first exit. Every car in the queue is inconvenienced as are any other drivers waiting to join the roundabout from other exits, because their journey is longer as result of one driver. That's inconsiderate driving. Nothing will happen but that's not the same as it isn't inconsiderate.
A full circle is 360degrees.911hope said:
Graveworm said:
Full circle is coming back the same way, as you describe it's not going around again to take the first exit. There is a correct lane for the first exit. Every car in the queue is inconvenienced as are any other drivers waiting to join the roundabout from other exits, because their journey is longer as result of one driver. That's inconsiderate driving. Nothing will happen but that's not the same as it isn't inconsiderate.
A full circle is 360degrees.Graveworm said:
Yes and that's how many degrees driving around the roundabout to go back the way you came is. Taking the first exit in a classic 4 exit roundabout is 90 - as per this thread it's 450..
Hmmm.... IsReally didn't expect this......I think you will find that 180 degrees is a U-turn.
Try rotating right by 90 degrees, then repeating and see which way you are facing.
360 is straight on after one lap.. that's 4 90 degree turns...
The rest can be derived by using the same principle.
Left after 3/4 of a lap clockwise is actually 270.
Turn RIGHT after 1 1/4 laps clockwise would be 450 degrees.
Good news is that left at first exit is actually 90 degrees.
Edited by 911hope on Sunday 24th September 23:09
911hope said:
Graveworm said:
Yes and that's how many degrees driving around the roundabout to go back the way you came is. Taking the first exit in a classic 4 exit roundabout is 90 - as per this thread it's 450..
Hmmm.... IsReally didn't expect this......I think you will find that 180 degrees is a U-turn.
Try rotating right by 90 degrees, then repeating and see which way you are facing.
360 is straight on after one lap.. that's 4 90 degree turns...
The rest can be derived by using the same principle.
Left after 3/4 of a lap clockwise is actually 270.
Turn RIGHT after 1 1/4 laps clockwise would be 450 degrees.
Good news is that left at first exit is actually 90 degrees.
Edited by 911hope on Sunday 24th September 23:09
A roundabout is (usually simplified as a circle, which is divided into 360 degrees.
You are talking about the direction of travel (Vector) when leaving a roundabout not the position on the roundabout or how many degrees they have travelled around the roundabout. Or, if you like, to complete a full circuit of a roundabout - 180 degrees to 180 degrees is a complete rotation or 360 degrees.
This is from maths is fun
Edited by Graveworm on Monday 25th September 00:21
Graveworm said:
911hope said:
Graveworm said:
Yes and that's how many degrees driving around the roundabout to go back the way you came is. Taking the first exit in a classic 4 exit roundabout is 90 - as per this thread it's 450..
Hmmm.... IsReally didn't expect this......I think you will find that 180 degrees is a U-turn.
Try rotating right by 90 degrees, then repeating and see which way you are facing.
360 is straight on after one lap.. that's 4 90 degree turns...
The rest can be derived by using the same principle.
Left after 3/4 of a lap clockwise is actually 270.
Turn RIGHT after 1 1/4 laps clockwise would be 450 degrees.
Good news is that left at first exit is actually 90 degrees.
Edited by 911hope on Sunday 24th September 23:09
A roundabout is (usually simplified as a circle, which is divided into 360 degrees.
You are talking about the direction of travel (Vector) when leaving a roundabout not the position on the roundabout or how many degrees they have travelled around the roundabout. Or, if you like, to complete a full circuit of a roundabout - 180 degrees to 180 degrees is a complete rotation or 360 degrees.
This is from maths is fun
Edited by Graveworm on Monday 25th September 00:21
180 degrees is u turn.
360 is full loop and carry on straight.
911hope said:
Graveworm said:
911hope said:
Graveworm said:
Yes and that's how many degrees driving around the roundabout to go back the way you came is. Taking the first exit in a classic 4 exit roundabout is 90 - as per this thread it's 450..
Hmmm.... IsReally didn't expect this......I think you will find that 180 degrees is a U-turn.
Try rotating right by 90 degrees, then repeating and see which way you are facing.
360 is straight on after one lap.. that's 4 90 degree turns...
The rest can be derived by using the same principle.
Left after 3/4 of a lap clockwise is actually 270.
Turn RIGHT after 1 1/4 laps clockwise would be 450 degrees.
Good news is that left at first exit is actually 90 degrees.
Edited by 911hope on Sunday 24th September 23:09
A roundabout is (usually simplified as a circle, which is divided into 360 degrees.
You are talking about the direction of travel (Vector) when leaving a roundabout not the position on the roundabout or how many degrees they have travelled around the roundabout. Or, if you like, to complete a full circuit of a roundabout - 180 degrees to 180 degrees is a complete rotation or 360 degrees.
This is from maths is fun
Edited by Graveworm on Monday 25th September 00:21
180 degrees is u turn.
360 is full loop and carry on straight.
How many degrees does the earth rotate about the sun in a year?
The direction of travel, or the direction the car is facing when it gets there is irrelevant to how many degrees it drove around the roundabout.
I am 99 percent sure you must know this so I won't bother going back and forth as I feel like I am being successfully trolled.
Edited by Graveworm on Monday 25th September 01:54
There does seem a propensity for unnecessary lingering in the outer lanes, even when it is feasible to move left.
A potential explanation for cars choosing the middle lane is the frequently observed left lane wheel track sinking causing wider tyre light weight cars to no longer track in a straight line.
A potential explanation for cars choosing the middle lane is the frequently observed left lane wheel track sinking causing wider tyre light weight cars to no longer track in a straight line.
Graveworm said:
911hope said:
Graveworm said:
911hope said:
Graveworm said:
Yes and that's how many degrees driving around the roundabout to go back the way you came is. Taking the first exit in a classic 4 exit roundabout is 90 - as per this thread it's 450..
Hmmm.... IsReally didn't expect this......I think you will find that 180 degrees is a U-turn.
Try rotating right by 90 degrees, then repeating and see which way you are facing.
360 is straight on after one lap.. that's 4 90 degree turns...
The rest can be derived by using the same principle.
Left after 3/4 of a lap clockwise is actually 270.
Turn RIGHT after 1 1/4 laps clockwise would be 450 degrees.
Good news is that left at first exit is actually 90 degrees.
Edited by 911hope on Sunday 24th September 23:09
A roundabout is (usually simplified as a circle, which is divided into 360 degrees.
You are talking about the direction of travel (Vector) when leaving a roundabout not the position on the roundabout or how many degrees they have travelled around the roundabout. Or, if you like, to complete a full circuit of a roundabout - 180 degrees to 180 degrees is a complete rotation or 360 degrees.
This is from maths is fun
Edited by Graveworm on Monday 25th September 00:21
180 degrees is u turn.
360 is full loop and carry on straight.
How many degrees does the earth rotate about the sun in a year?
The direction of travel, or the direction the car is facing when it gets there is irrelevant to how many degrees it drove around the roundabout.
I am 99 percent sure you must know this so I won't bother going back and forth as I feel like I am being successfully trolled.
Edited by Graveworm on Monday 25th September 01:54
Not a trolling activity here. Just a correction of statement.
a "straight angle" does not mean straight-on. It actually means 180 degree rotation.
https://byjus.com/maths/straight-angle/#:~:text=In...
I see how the use of this term causes confusion.
If you took a pencil and set it on a piece of paper, marked it's position, then rotated 180degrees around one end, you will find the stick and mark form a straight line. That's where the name comes from.
BUT, you will notice the stick is facing in the opposite direction, so this scenario does not model a car going straight on at a roundabout.
Now back to the clock hands question you raised, hands going from 6 around the clock face is indeed 360 degress. BUT the hands are facing the same way as they were at the beginning. This models one lap of the roundabout, then going straight on.
Going round a roundabout and drive back on the road that you arrived on, you will find that your car is facing the opposite direction to your approach.
This means you have done an accumulated 180 degree rotation.
You might think that because you have driven round a roundabout, that you have rotated 360 degrees, but you have not until the car is facing the same way as the approach.
Had the car been at a tangent to the circle and then done a full lap, then it would be at the same point and have rotated 360 degrees. But in the u-turn scenario, the radial entry and exists subtracts 180 degrees.
So, to conclude with a summary.
Rotation of a car approaching a roundabout (4 equally spaced exits) and leaving at each of the exists, shows the following rotation (considering clockwise as a positive rotation) 1st and 2nd possible exists shown in the following list.
1st exit (Left) -90degrees, +270 (so called slingshot)
2nd exit (straight) 0 degrees, 360 (full lap, then straight on)
3rd exit (right) +90 degrees, 450 (right after a lap)
4th exit (u-turn, or back from where it came) 180 degrees, 540 (u-turn after a lap)
Hope this helps.
911hope said:
Graveworm said:
911hope said:
Graveworm said:
911hope said:
Graveworm said:
Yes and that's how many degrees driving around the roundabout to go back the way you came is. Taking the first exit in a classic 4 exit roundabout is 90 - as per this thread it's 450..
Hmmm.... IsReally didn't expect this......I think you will find that 180 degrees is a U-turn.
Try rotating right by 90 degrees, then repeating and see which way you are facing.
360 is straight on after one lap.. that's 4 90 degree turns...
The rest can be derived by using the same principle.
Left after 3/4 of a lap clockwise is actually 270.
Turn RIGHT after 1 1/4 laps clockwise would be 450 degrees.
Good news is that left at first exit is actually 90 degrees.
Edited by 911hope on Sunday 24th September 23:09
A roundabout is (usually simplified as a circle, which is divided into 360 degrees.
You are talking about the direction of travel (Vector) when leaving a roundabout not the position on the roundabout or how many degrees they have travelled around the roundabout. Or, if you like, to complete a full circuit of a roundabout - 180 degrees to 180 degrees is a complete rotation or 360 degrees.
This is from maths is fun
Edited by Graveworm on Monday 25th September 00:21
180 degrees is u turn.
360 is full loop and carry on straight.
How many degrees does the earth rotate about the sun in a year?
The direction of travel, or the direction the car is facing when it gets there is irrelevant to how many degrees it drove around the roundabout.
I am 99 percent sure you must know this so I won't bother going back and forth as I feel like I am being successfully trolled.
Edited by Graveworm on Monday 25th September 01:54
Not a trolling activity here. Just a correction of statement.
a "straight angle" does not mean straight-on. It actually means 180 degree rotation.
https://byjus.com/maths/straight-angle/#:~:text=In...
I see how the use of this term causes confusion.
If you took a pencil and set it on a piece of paper, marked it's position, then rotated 180degrees around one end, you will find the stick and mark form a straight line. That's where the name comes from.
BUT, you will notice the stick is facing in the opposite direction, so this scenario does not model a car going straight on at a roundabout.
Now back to the clock hands question you raised, hands going from 6 around the clock face is indeed 360 degress. BUT the hands are facing the same way as they were at the beginning. This models one lap of the roundabout, then going straight on.
Going round a roundabout and drive back on the road that you arrived on, you will find that your car is facing the opposite direction to your approach.
This means you have done an accumulated 180 degree rotation.
You might think that because you have driven round a roundabout, that you have rotated 360 degrees, but you have not until the car is facing the same way as the approach.
Had the car been at a tangent to the circle and then done a full lap, then it would be at the same point and have rotated 360 degrees. But in the u-turn scenario, the radial entry and exists subtracts 180 degrees.
So, to conclude with a summary.
Rotation of a car approaching a roundabout (4 equally spaced exits) and leaving at each of the exists, shows the following rotation (considering clockwise as a positive rotation) 1st and 2nd possible exists shown in the following list.
1st exit (Left) -90degrees, +270 (so called slingshot)
2nd exit (straight) 0 degrees, 360 (full lap, then straight on)
3rd exit (right) +90 degrees, 450 (right after a lap)
4th exit (u-turn, or back from where it came) 180 degrees, 540 (u-turn after a lap)
Hope this helps.
When it arrives at exit 1 it has travelled 90 degrees at the straight on point 180, at the right turn 270 and back at the origin 360. If it returns the way it came the car has indeed rotated by 180 degrees but had to drive 360 degrees around the roundabout to achieve it. If it parked up facing in any direction never to move again, it would still have driven 360 degrees around the roundabout. Likewise if was doing doughnuts the whole time the car could have rotated many times - still only once around the roundabout.
How do you describe how far around a circle or orbit anything else has travelled, clock hands, race cars, planets etc. Planets are indeed always rotating about their own axis, but how often and how far, like the car is irrelevant when describing their orbit. A full circuit is 360 degrees.
https://youtu.be/ws37b-7UrJk?feature=shared
Edited by Graveworm on Monday 25th September 11:25
Graveworm said:
It doesn't help because despite it being pointed out many times, you keep describing the relative aspect of the car, rather than how far it has driven around the roundabout. That is explicitly what I wrote and what is being discussed.
When it arrives at exit 1 it has travelled 90 degrees at the straight on point 180, at the right turn 270 and back at the origin 360. If it returns the way it came the car has indeed rotated by 180 degrees but had to drive 360 degrees around the roundabout to achieve it. If it parked up facing in any direction never to move again, it would still have driven 360 degrees around the roundabout. Likewise if was doing doughnuts the whole time the car could have rotated many times - still only once around the roundabout.
How do you describe how far around a circle or orbit anything else has travelled, clock hands, race cars, planets etc. Planets are indeed always rotating about their own axis, but how often and how far, like the car is irrelevant when describing their orbit. A full circuit is 360 degrees.
https://youtu.be/ws37b-7UrJk?feature=shared
A full circuit would be 360 degrees, but a u turn round an object is not a full circuit.When it arrives at exit 1 it has travelled 90 degrees at the straight on point 180, at the right turn 270 and back at the origin 360. If it returns the way it came the car has indeed rotated by 180 degrees but had to drive 360 degrees around the roundabout to achieve it. If it parked up facing in any direction never to move again, it would still have driven 360 degrees around the roundabout. Likewise if was doing doughnuts the whole time the car could have rotated many times - still only once around the roundabout.
How do you describe how far around a circle or orbit anything else has travelled, clock hands, race cars, planets etc. Planets are indeed always rotating about their own axis, but how often and how far, like the car is irrelevant when describing their orbit. A full circuit is 360 degrees.
https://youtu.be/ws37b-7UrJk?feature=shared
Edited by Graveworm on Monday 25th September 11:25
What about the segment that is missed by exiting before the point of entrance?
Then consider the direction changes caused by the entrance and exit.. both counter to the section of a circle.
On a large motorway roundabout this could easily be a huge segment.
Have a look at what NASA defines orbiting as.
Consider straight on, in terms of accumulated steering angle, as a car drives past an object entering to exiting. Left.right, straight, right,left. The accumulation is zero, just the same as driving straight over the object.
To achieve 180 degrees, it would need to start on the roundabout facing one direction, drive a semicircle and be facing tho opposite way on the other side of the roundabout.
In that situation, the rotation would be 180 degrees and the arc described by the motion of the car relative to the circle centre would also be 180 degrees.
Edited by 911hope on Monday 25th September 17:37
911hope said:
Graveworm said:
It doesn't help because despite it being pointed out many times, you keep describing the relative aspect of the car, rather than how far it has driven around the roundabout. That is explicitly what I wrote and what is being discussed.
When it arrives at exit 1 it has travelled 90 degrees at the straight on point 180, at the right turn 270 and back at the origin 360. If it returns the way it came the car has indeed rotated by 180 degrees but had to drive 360 degrees around the roundabout to achieve it. If it parked up facing in any direction never to move again, it would still have driven 360 degrees around the roundabout. Likewise if was doing doughnuts the whole time the car could have rotated many times - still only once around the roundabout.
How do you describe how far around a circle or orbit anything else has travelled, clock hands, race cars, planets etc. Planets are indeed always rotating about their own axis, but how often and how far, like the car is irrelevant when describing their orbit. A full circuit is 360 degrees.
https://youtu.be/ws37b-7UrJk?feature=shared
A full circuit would be 360 degrees, but a u turn round an object is not a full circuit.When it arrives at exit 1 it has travelled 90 degrees at the straight on point 180, at the right turn 270 and back at the origin 360. If it returns the way it came the car has indeed rotated by 180 degrees but had to drive 360 degrees around the roundabout to achieve it. If it parked up facing in any direction never to move again, it would still have driven 360 degrees around the roundabout. Likewise if was doing doughnuts the whole time the car could have rotated many times - still only once around the roundabout.
How do you describe how far around a circle or orbit anything else has travelled, clock hands, race cars, planets etc. Planets are indeed always rotating about their own axis, but how often and how far, like the car is irrelevant when describing their orbit. A full circuit is 360 degrees.
https://youtu.be/ws37b-7UrJk?feature=shared
Edited by Graveworm on Monday 25th September 11:25
What about the segment that is missed by exiting before the point of entrance?
Then consider the direction changes caused by the entrance and exit.. both counter to the section of a circle.
On a large motorway roundabout this could easily be a huge segment.
Have a look at what NASA defines orbiting as.
Consider straight on, in terms of accumulated steering angle, as a car drives past an object entering to exiting. Left.right, straight, right,left. The accumulation is zero, just the same as driving straight over the object.
To achieve 180 degrees, it would need to start on the roundabout facing one direction, drive a semicircle and be facing tho opposite way on the other side of the roundabout.
In that situation, the rotation would be 180 degrees and the arc described by the motion of the car relative to the circle centre would also be 180 degrees.
Edited by 911hope on Monday 25th September 17:37
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