Author Topic: How do we value our time?  (Read 3594 times)

culzean

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Re: How do we value our time?
« Reply #15 on: August 08, 2021, 02:50:07 PM »

If it had a 40mph mandatory limit, which is the maximum traffic throughflow speed, it would have worked much better, it reduces the concertina effect.


Many people do not realise that a lower speed limit in heavy traffic makes traffic flow much better,  when someone brakes at higher speed it causes a 'wave' to travel back down the motorway of other vehicles braking in response.  Very often following traffic can be brought to a halt, , as people brake fairly often at higher speeds in heavy traffic the waves continue to be generated,  is that what you meant by 'concertina effect' ?

https://phys.org/news/2007-12-traffic-mystery-mathematicians.html

http://trafficwaves.org/
« Last Edit: August 08, 2021, 02:58:16 PM by culzean »
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

embee

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Re: How do we value our time?
« Reply #16 on: August 08, 2021, 03:57:03 PM »
... is that what you meant by 'concertina effect' ?
...
Yes.
There are lots of mathematical models around in different institutions, but all come to basically the same conclusions.
It varies a bit by country (culture/habit/road type etc) but typically the best flow and throughput of vehicles is when the speed is around 70-80kph, something like 45mph. This reduces the over-reaction of drivers to perceived events and minimises the excessive braking as you referred to.
On congested motorways you really do make better (in several senses of the word) progress if the traffic is slowed down. Variable speed limits (VSL) for congestion easing usually change in small increments to avoid the sudden step changes, probably 10mph steps in sequence, 70 -> 60 -> 50 -> 40. It's in your best interests and works, as long as people obey the limits.
« Last Edit: August 08, 2021, 03:59:20 PM by embee »

Jocko

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Re: How do we value our time?
« Reply #17 on: August 08, 2021, 04:07:13 PM »
The other day I came up to a 50 mph sign at 50 mph and about 30 feet from it, it changed to 40 mph. I had to slam on the anchors, as the gantry had a speed camera on it. Didn't want to take any chances of getting a ticket.

nowster

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Re: How do we value our time?
« Reply #18 on: August 08, 2021, 04:39:57 PM »
The other day I came up to a 50 mph sign at 50 mph and about 30 feet from it, it changed to 40 mph. I had to slam on the anchors, as the gantry had a speed camera on it. Didn't want to take any chances of getting a ticket.

As I said before, there is a delay between the speed restriction changing and the HADECS3 camera enforcing it. It may not be as much as a minute as I said before, but it should be long enough to prevent such panic braking.

culzean

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Re: How do we value our time?
« Reply #19 on: August 08, 2021, 04:43:10 PM »
One thing I noticed on congested motorways ( the M6 is always congested J4 to J10, mainly people from B'ham hopping on and off ) - years ago all 3 or 4 lanes full of traffic moving at say 30 to 40 ( but no variable speed limit in place ).  Stay in centre lane to ease traffic in nearside lane to give people entering motorway a bit more room, 'fast lane' seems to be moving a bit faster so people move into it,  extra volume of traffic in fast lane slows it down, now centre lane seems to be flowing faster,  people move into it ( the impatient ones ), extra volume of traffic in centre lane slows it down, people move into fast lane... ( you see where this is going ) - I used to stay in centre lane and see the same vehicles ( me going past them ) over and over again - if they stayed in lane when motorway is chockers everyone has an easier time.   Remember every lane is chock full of bumper to bumper vehicles so no problem to stay in centre lane.  I noticed more recently when variable speed limits came in,  traffic flowed much better all round.
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

culzean

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Re: How do we value our time?
« Reply #20 on: August 08, 2021, 04:44:53 PM »
The other day I came up to a 50 mph sign at 50 mph and about 30 feet from it, it changed to 40 mph. I had to slam on the anchors, as the gantry had a speed camera on it. Didn't want to take any chances of getting a ticket.

As I said before, there is a delay between the speed restriction changing and the HADECS3 camera enforcing it. It may not be as much as a minute as I said before, but it should be long enough to prevent such panic braking.

Maybe while speed limit changing and cameras not active at that speed they could flash the speed limit,  and goes steady when cameras active.
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

150234

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Re: How do we value our time?
« Reply #21 on: August 09, 2021, 02:31:52 PM »
Comparing 200 miles at 70mph and 50 mpg with 200 miles at 60 mph and 60 mpg saves half an hour of journey time and costs an extra £4 in fuel, valuing our time at £8 per hour, about the minimum wage.  If the government is serious about reducing emissions, a national 60 mph speed limit would make a significant difference.  It would also reduce the frequency and severity of road accidents.  Probably not a vote winner though!
Absolutley not. If anything happens to UK speed limits they should be increased to 80 at least. Ideally the outside lane would be derestricted and allow people to get on a bit.

Let's be honest, 70 is trundling and 80 is hardly pushing on.

Kremmen

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Re: How do we value our time?
« Reply #22 on: August 09, 2021, 02:55:13 PM »
I've seen this motorway speed limit discussed/argued about on many forums. It's a marmite subject.

Some want 60, some want 80+
Let's be careful out there !

culzean

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Re: How do we value our time?
« Reply #23 on: August 09, 2021, 03:03:16 PM »
Comparing 200 miles at 70mph and 50 mpg with 200 miles at 60 mph and 60 mpg saves half an hour of journey time and costs an extra £4 in fuel, valuing our time at £8 per hour, about the minimum wage.  If the government is serious about reducing emissions, a national 60 mph speed limit would make a significant difference.  It would also reduce the frequency and severity of road accidents.  Probably not a vote winner though!
Absolutley not. If anything happens to UK speed limits they should be increased to 80 at least. Ideally the outside lane would be derestricted and allow people to get on a bit.

Let's be honest, 70 is trundling and 80 is hardly pushing on.

If speed limit increased to 80, cars would do 90 ( speed limit at 70 now and most cars do 80 ).  De-restricting the outside lane would result in horrific crashes as people in centre lane pull out at say 70 to overtake, and a car in that lane doing 120.  Things go wrong frighteningly fast at 70, at 90+ most drivers could not react in time.  Everyone thinks they are are a great driver ( until the laws of physics prove them wrong ) but we share the roads with a lot of other people, and their safety should be our number one priority.  Road deaths in Germany significantly higher than in UK, I wonder why ?  If people want us to take global warming seriously they there are great fuel savings to be made by lowering the speed limits,  electric cars do not like motorways,  the remaining battery power meter drops like a stone in freefall at motorway speeds.   The Jazz that went Lands End to John O'Groats on a single tank of fuel stuck to around 40mph. 


I am beginning to suspect 150234 is a provocative troll... just my opinion ATM.
« Last Edit: August 09, 2021, 03:05:18 PM by culzean »
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

BadgerMk3

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Re: How do we value our time?
« Reply #24 on: August 09, 2021, 09:39:59 PM »
The other day I came up to a 50 mph sign at 50 mph and about 30 feet from it, it changed to 40 mph. I had to slam on the anchors, as the gantry had a speed camera on it. Didn't want to take any chances of getting a ticket.

As I said before, there is a delay between the speed restriction changing and the HADECS3 camera enforcing it. It may not be as much as a minute as I said before, but it should be long enough to prevent such panic braking.

Playing devil's advocate... what is your source of information for this suggested delay in speed limit change enforcement?

nowster

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Re: How do we value our time?
« Reply #25 on: August 09, 2021, 11:23:12 PM »
The other day I came up to a 50 mph sign at 50 mph and about 30 feet from it, it changed to 40 mph. I had to slam on the anchors, as the gantry had a speed camera on it. Didn't want to take any chances of getting a ticket.

As I said before, there is a delay between the speed restriction changing and the HADECS3 camera enforcing it. It may not be as much as a minute as I said before, but it should be long enough to prevent such panic braking.

Playing devil's advocate... what is your source of information for this suggested delay in speed limit change enforcement?

https://www.ballymenatimes.com/lifestyle/cars/speeders-get-60-second-grace-period-on-smart-motorways-1383495

https://www.motoringresearch.com/car-news/speed-grace-period-smart-motorways/

What I can't find online is the Auto Express report behind this.

Kremmen

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Re: How do we value our time?
« Reply #26 on: August 10, 2021, 04:00:01 AM »
If I drove under a gantry sign that had just changed from say 50 to 40 I certainly wouldn't brake but just ease off the throttle and let the car slow normally.

Then mark/save my dashcam footage just in case.

Response from Highways England on another forum :

Quote
Thank you for your enquiry of 8^th December 2019 concerning speed
restrictions on the M6 southbound Junction 10. According to our records,
at the enforcement site on the date and time requested, a mandatory speed
limit of 50mph was set at 00:55:33 due to an incident on the network.
Enforcement of speed restrictions is the responsibility of the police. we
are unable to comment on, or provide you with advise about alleged
offences. Within the judicial process, information held by the police will
always take legal precedence. This response is for information only and
cannot be used in court for the purpose of challenging an allegation of
speeding. When a mandatory speed limit displays or changes on the overhead
AMI signal, there is an automatic delay before enforcement can begin
against the newly displayed limit. The flash units can still activate
during this period, even though the new limit is not enforced. In this
situation drivers are not expected to brake sharply but rather reduce
their speed so that they are within the speed limit as soon as it is safe
to do so.

Highways England are not responsible for the enforcement of speed limits,
that responsibility lies with the relevant police force.
« Last Edit: August 10, 2021, 04:07:25 AM by Kremmen »
Let's be careful out there !

BadgerMk3

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Re: How do we value our time?
« Reply #27 on: August 10, 2021, 09:25:42 AM »
Again playing devil's advocate...

So in general,  the source is the good old internet.  ::)

Even the quoted supposed response from Highways England is slightly contradictory, but also states the responsibility for prosecution lies with the relevant police force. Even taking that quote at face value, I would suggest that is the pertinent statement.

In summary, I would suggest it is your decision how you react to a sudden change in speed limit, and subsequently a police decision on how they react to any committed offences.

Also, just an observation - there is no such thing as a "fast lane" on a motorway.

150234

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Re: How do we value our time?
« Reply #28 on: August 10, 2021, 01:13:44 PM »
Comparing 200 miles at 70mph and 50 mpg with 200 miles at 60 mph and 60 mpg saves half an hour of journey time and costs an extra £4 in fuel, valuing our time at £8 per hour, about the minimum wage.  If the government is serious about reducing emissions, a national 60 mph speed limit would make a significant difference.  It would also reduce the frequency and severity of road accidents.  Probably not a vote winner though!
Absolutley not. If anything happens to UK speed limits they should be increased to 80 at least. Ideally the outside lane would be derestricted and allow people to get on a bit.

Let's be honest, 70 is trundling and 80 is hardly pushing on.

If speed limit increased to 80, cars would do 90 ( speed limit at 70 now and most cars do 80 ).  De-restricting the outside lane would result in horrific crashes as people in centre lane pull out at say 70 to overtake, and a car in that lane doing 120.  Things go wrong frighteningly fast at 70, at 90+ most drivers could not react in time.  Everyone thinks they are are a great driver ( until the laws of physics prove them wrong ) but we share the roads with a lot of other people, and their safety should be our number one priority.  Road deaths in Germany significantly higher than in UK, I wonder why ?  If people want us to take global warming seriously they there are great fuel savings to be made by lowering the speed limits,  electric cars do not like motorways,  the remaining battery power meter drops like a stone in freefall at motorway speeds.   The Jazz that went Lands End to John O'Groats on a single tank of fuel stuck to around 40mph. 


I am beginning to suspect 150234 is a provocative troll... just my opinion ATM.
There is plenty of rubbish to pick apart here.

Most cars would indeed do 90 but we would get places far faster and you don't have to do 90 if you don't want to, there are two others lanes with slower moving vehicles for those stuck in the 1980's to enjoy.

As for things going wrong fast, I disagree massively. They just don't. Everyone bangs on about 70 mph and how fast it is, but next time you're doing 70 look at a gantry or a sign a long way ahead and watch how long it takes to come at you. Even closer range stuff like the catseyes don't come at you fast, let alone a car doing 20mph less than you. 70mph really isn't that fast and it's surprising how long stuff takes to come at you.

120mph is unrealistic for many as either their cars won't do it or they just couldn't bring themselfs to do it. In reality on a derestriced motorway most people are two much of a fanny to do much more than 90 anyway. Look at the Honda Jazz. Tops out at 110 on the flat (although on a long steep down hill I did once get 122 which was interesting) so very few people will ever achieve that.

As for sharing roads with others, if you move into the outside lane without correctly judging the overspeed of the approaching car, that's not the 120mph cars fault, it's yours, plain and simple. If people could drive we could all do 100 but because some people make a right meal out of driving we are all at a crawl.

Car crumple zones, seatbelts and airbags are constantly getting better and so it car safety in general or why aren't we upgrading out roads to suit?

Jocko

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Re: How do we value our time?
« Reply #29 on: August 10, 2021, 01:14:45 PM »
Just as an aside, there was no vehicle within half a mile of me when I slapped on the anchors. And I did lock the dash cam file.

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