M1 Speed Limit In Sheffield

[Arnold_Lane 0]

1 hour ago, Jim Hardie said:

My analysis, be it right or wrong, is to compare motorway traffic‘s potential to pollute over a fixed distance at 60mph and 70mph. I thought that was what the proposed trial and this thread is all about.
I realise it’s a simplistic model and in practice there will be lots of variables, but I’ve given my calculations. Let’s see yours.

Your analysis assumes a different number of cars pass through at 60 than at 70.  Why?  The number of people using the motorway is fixed.  Your analysis is flawed for that reason.

[Jim Hardie 527]

35 minutes ago, Arnold_Lane said:

Your analysis assumes a different number of cars pass through at 60 than at 70.  Why?  The number of people using the motorway is fixed.  Your analysis is flawed for that reason.

Ok, let's assume there is a hold up somewhere ahead and the vehicles are crawling along at walking pace. Do you suppose there are still the same number of vehicles on one mile of motorway as there would be with free flowing traffic? No, because they will be about ten feet apart.

By the same token, at 60mph they will be closer together than at 70mph, therefore the number of vehicles on the motorway over one mile is not fixed. Where is the flaw?

[Arnold_Lane 0]

6 minutes ago, Jim Hardie said:

Ok, let's assume there is a hold up somewhere ahead and the vehicles are crawling along at walking pace. Do you suppose there are still the same number of vehicles on one mile of motorway as there would be with free flowing traffic? No, because they will be about ten feet apart.

By the same token, at 60mph they will be closer together than at 70mph, therefore the number of vehicles on the motorway over one mile is not fixed. Where is the flaw?

Read my post again.

[Jim Hardie 527]

4 minutes ago, Arnold_Lane said:

Read my post again.

I don’t need to.

[Arnold_Lane 0]

4 minutes ago, Jim Hardie said:

I don’t need to.

Realised your mistake then?

 

You have a different “maximum number of cars“ in your calculations for 60 and 70.

 

The number of cars on the motorway doesn’t change though.

Edited September 18, 2020 by Arnold_Lane

[Jim Hardie 527]

Just now, Arnold_Lane said:

Realised your mistake then?

I don’t believe I’ve made a mistake. The proposed trial is to compare the level of emissions at 60mph against the level at 70mph over a fixed distance of motorway. I think I’ve adequately demonstrated that there will be more vehicles over that same fixed distance at the lower speed. But if you think differently there’s nothing more I can do about it in the absence of your calculations.

[Arnold_Lane 0]

3 minutes ago, Jim Hardie said:

I don’t believe I’ve made a mistake. The proposed trial is to compare the level of emissions at 60mph against the level at 70mph over a fixed distance of motorway. I think I’ve adequately demonstrated that there will be more vehicles over that same fixed distance at the lower speed. But if you think differently there’s nothing more I can do about it in the absence of your calculations.

Where did the extra vehicles come from?

 

Your “maximum number of cars” is the flaw.  It’s not a variable.  

 

Edited September 18, 2020 by Arnold_Lane

[Jim Hardie 527]

31 minutes ago, Arnold_Lane said:

Where did the extra vehicles come from?

 

Your “maximum number of cars” is the flaw.  It’s not a variable.  

 

Bad form to edit your post after I've replied to it but never mind.

You seem to have conveniently ignored the fact that the trial is over a fixed distance.

The maximum number of cars on one mile of motorway is calculated by dividing the number of feet in one mile by the total of the recognised stopping distance for the speed in question and the average length of a car. As I've already admitted, a simplistic way to calculate the number of vehicles on that one mile, but the average driver knows he can safely follow the vehicle in front more closely at lower speeds, and in my experience does so. 

Therefore, there will be more vehicles on that one mile at the lower speed. So again, where is the flaw?

[Arnold_Lane 0]

54 minutes ago, Jim Hardie said:

Bad form to edit your post after I've replied to it but never mind.

You seem to have conveniently ignored the fact that the trial is over a fixed distance.

The maximum number of cars on one mile of motorway is calculated by dividing the number of feet in one mile by the total of the recognised stopping distance for the speed in question and the average length of a car. As I've already admitted, a simplistic way to calculate the number of vehicles on that one mile, but the average driver knows he can safely follow the vehicle in front more closely at lower speeds, and in my experience does so. 

Therefore, there will be more vehicles on that one mile at the lower speed. So again, where is the flaw?

I know how you’ve calculated maximum number of cars and I’ve told you that’s where the flaw is.  

 

Say 10,000 cars travel between J33 and J34 per day.  Using your units;

 

At 60 mph, it’s 60 x 10,000 pollutant seconds per mile.

 

At 70 mph it’s 51.42 x 10,000 pollutant seconds per mile.

 

60/51.42 = 1.167.  

 

The “maximum number of cars” you are using is entirely irrelevant.  Your analysis isn’t simplistic it’s just wrong.  The number of cars that have to get between J33 and J34 does not change regardless of how fast they do it.

Edited September 19, 2020 by Arnold_Lane

[Jim Hardie 527]

7 hours ago, Arnold_Lane said:

I know how you’ve calculated maximum number of cars and I’ve told you that’s where the flaw is.  

 

Say 10,000 cars travel between J33 and J34 per day.  Using your units;

 

At 60 mph, it’s 60 x 10,000 pollutant seconds per mile.

 

At 70 mph it’s 51.42 x 10,000 pollutant seconds per mile.

 

60/51.42 = 1.167.  

 

The “maximum number of cars” you are using is entirely irrelevant.  Your analysis isn’t simplistic it’s just wrong.  The number of cars that have to get between J33 and J34 does not change regardless of how fast they do it.

Amazing what a night’s sleep can do. I think you’ve won the argument.
I used the ‘maximum number’ to demonstrate that there can be more vehicles on that particular stretch of motorway at the lower speed at any one time. However for that argument to work, it would have to be at that capacity 24 hours a day and it won’t be.
 

[Rockers rule 673]

13 minutes ago, Jim Hardie said:

Amazing what a night’s sleep can do. I think you’ve won the argument.
I used the ‘maximum number’ to demonstrate that there can be more vehicles on that particular stretch of motorway at the lower speed at any one time. However for that argument to work, it would have to be at that capacity 24 hours a day and it won’t be.
 

Don't tell him that Jim.

I thought you were my saviour. LOL.  

 

I still say 80 mph and better training for motorway use.

 

Keep safe & use lane two more.

[Jim Hardie 527]

7 minutes ago, Rockers rule said:

Don't tell him that Jim.

I thought you were my saviour. LOL.  

 

I still say 80 mph and better training for motorway use.

 

Keep safe & use lane two more.

Lol, sorry to let you down, Rockers. At least I had a go.