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 Post subject: Speedos
PostPosted: Thu Oct 29, 2009 11:37 
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Another thing i'd like to discuss...

When do you check your speedo? And why?

Obviously you'll be checking it to know your speed, but what I want to look at is why you've considered it necessary to know your speed in numerical terms.


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 Post subject: Re: Speedos
PostPosted: Thu Oct 29, 2009 13:37 
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This has been covered a few times on this site in the past :)

I will start you with a few.

1. To avoid prosecution, I can usually keep my speed legal without reference to the speedo, however there is still a risk I will go 1-2mph over and it is one I do not care to take.
2. Fuel economy, it is easy to allow your speed to creep up on a motorway, for example, if I have to accelerate to make a clean pass a speedo check is useful when dropping back to cruise.
3. If I know what speed I am doing and how far to a destination or junction I know roughly how long it should take.
4. Checked as part of a general instrument scan, fuel, temp, warning lights, time, etc. or if using a sat-nav distance to next turn.

Nearly forgot this one
5. When leaving a motorway, especially when dropping to urban rather than NSL roads, it can sometimes take a minute to drop my speed perception back down so using a speedo helps me make the shift quickly.

P.S. If I am doing a track day the only time I look at the speedo is when entering the pit lane, temp & oil pressure, and less frequently fuel are the instruments I check on track.

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 Post subject: Re: Speedos
PostPosted: Thu Oct 29, 2009 20:31 
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I thought this was going to be about swimming costumes. :)

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 Post subject: Speedometers
PostPosted: Fri Oct 30, 2009 01:41 
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toltec wrote:
1. To avoid prosecution, I can usually keep my speed legal without reference to the speedo, however there is still a risk I will go 1-2mph over and it is one I do not care to take.
In the five boroughs of NY, one can safely do 10 to 12 MpH over the posted speed 'limit' without fear of being pulled over. I haven't needed to check in a while, since I seldom drive through traps during traffic conditions which could physically permit extralegal speeds.
Quote:
2. Fuel economy, it is easy to allow your speed to creep up on a motorway, for example, if I have to accelerate to make a clean pass a speedo check is useful when dropping back to cruise.
Had I cruise control AND a fuel consumption readout, the speedometer might become redundant after a while. Few, if any vehicles improve their highway MpG above 60 to 65 MpH, so I just keep it between 60 & 65MpH on the highway.
Quote:
3. If I know what speed I am doing and how far to a destination or junction I know roughly how long it should take.
A satnav would suffice here.
Quote:
4. Checked as part of a general instrument scan, fuel, temp, warning lights, time, etc. or if using a sat-nav distance to next turn.
In this case, I hardly notice the number anymore.
Quote:
5. When leaving a motorway, especially when dropping to urban rather than NSL roads, it can sometimes take a minute to drop my speed perception back down so using a speedo helps me make the shift quickly.
I still do this every now and again. I've found it helpful, but almost never necessary.

Generally, the speedometer is only necessary because someone else cares about the number.

However, in inclement weather, I find myself looking at it if my 'g-meter' gets nervous before the entry of a turn, then I'll check to make sure I'm entering the turn at a speed no greater than 10MpH over the posted curve advisory speed.

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2) Nothing gets hit, except to protect others; see Rule#1
3) The Laws of Physics are invincible and immutable - so-called 'laws' of men are not
4) You are always immediately and ultimately responsible for your safety first, then proximately responsible for everyone's
Do not let other road users' mistakes become yours, nor yours become others
5) The rest, including laws of the land, is thoughtful observation, prescience, etiquette, decorum, and cooperation


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 Post subject: Re: Speedos
PostPosted: Fri Oct 30, 2009 05:59 
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Apart for neigh all the points made above .... although we could take a query into the differences of friction that water and air have ! :) ...
Speedo check are only 'necessary' to aid knowledge of stopping ability, as part of the build up of collective information needed as we travel along.
Learning what speed one is traveling at (apart from legal compliance), helps to enable a fuller picture of information that helps us learn to judge from different aspects.
So the distance 'clear' in front of the car needs to be enough, to know that we can stop in, allowing for all possibilities (of hazard), so understand how fast one is traveling helps our judgment of the overall risk management - all necessary to drive safely.
We can of course drive safely without the 'need' of any speedo. One can drive better and more precisely with speedo and revometer, working together, to provide better control of the engine input / output. (Sorry tired and could better phrase this I am sure)!

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 Post subject: Re: Speedos
PostPosted: Fri Oct 30, 2009 10:48 
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SafeSpeedv2 wrote:
Apart for neigh all the points made above .... although we could take a query into the differences of friction that water and air have ! :) ...
Speedo check are only 'necessary' to aid knowledge of stopping ability,

That is a useful aid, but it's not the only one. Another is to ensure behaviour remains predictable to other road users. Other road users can reasonably expect drivers to remain within the speed limit (except motorways and other roads where limits are needlessly low and many already exceed it anyway) and can be reasonably expected (rightly or wrongly) to act based on that.

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PostPosted: Fri Oct 30, 2009 12:48 
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Steve wrote:
Another is to ensure behaviour remains predictable to other road users. Other road users can reasonably expect drivers to remain within the speed limit (except motorways and other roads where limits are needlessly low and many already exceed it anyway) and can be reasonably expected (rightly or wrongly) to act based on that.
Wouldn't that make the expected speed in a given road area the , um, 'thermostat setting'?
In cases where the reasonable and prudent majority normally tend to exceed the 'speedostat', if profit motives are removed, the only reason I can think of for the low 'setting', would be to permit the drivers at the lower end of the range to [continue to] participate in the social benefits of motoring.

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The Rules for ALL ROAD USERS:
1) No one gets hurt
2) Nothing gets hit, except to protect others; see Rule#1
3) The Laws of Physics are invincible and immutable - so-called 'laws' of men are not
4) You are always immediately and ultimately responsible for your safety first, then proximately responsible for everyone's
Do not let other road users' mistakes become yours, nor yours become others
5) The rest, including laws of the land, is thoughtful observation, prescience, etiquette, decorum, and cooperation


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PostPosted: Fri Oct 30, 2009 13:12 
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SafeSpeedv2 wrote:
Apart for neigh all the points made above .... although we could take a query into the differences of friction that water and air have ! :) ...
Speedo check are only 'necessary' to aid knowledge of stopping ability, as part of the build up of collective information needed as we travel along.
Learning what speed one is traveling at (apart from legal compliance), helps to enable a fuller picture of information that helps us learn to judge from different aspects.
So the distance 'clear' in front of the car needs to be enough, to know that we can stop in, allowing for all possibilities (of hazard), so understand how fast one is traveling helps our judgment of the overall risk management - all necessary to drive safely.
We can of course drive safely without the 'need' of any speedo. One can drive better and more precisely with speedo and revometer, working together, to provide better control of the engine input / output. (Sorry tired and could better phrase this I am sure)!
In a related fashion, I remember when I used the speedometer as a tool to compare turning entry [and I suppose exit] speeds, and thus calibrating my internal lateral 'g-meter' (below 9MpH=slow/tight;, 10-13MpH=normal; 14-17MpH pushing a bit, 18+ pushing hard/wide). ('Slow in' permits 'fast out'.)
Lacking here is the ability to numerically measure the tightness/looseness of the turn.

Which makes me wonder ... If the speedometer can be a learning tool, could a longitudinal/lateral accelerometer also become one? Perhaps there would be benefits to including numerical accelerometers to vehicles other than high-end sports cars?

_________________
The Rules for ALL ROAD USERS:
1) No one gets hurt
2) Nothing gets hit, except to protect others; see Rule#1
3) The Laws of Physics are invincible and immutable - so-called 'laws' of men are not
4) You are always immediately and ultimately responsible for your safety first, then proximately responsible for everyone's
Do not let other road users' mistakes become yours, nor yours become others
5) The rest, including laws of the land, is thoughtful observation, prescience, etiquette, decorum, and cooperation


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PostPosted: Fri Oct 30, 2009 14:21 
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The Rush wrote:
Wouldn't that make the expected speed in a given road area the , um, 'thermostat setting'?

IMO: this depends on how expected is defined.
'Expected' from a pedestrian's points of view is being within the speed limit; 'expected' from a driver's points of view is safe progress without causing undue inconvenience/stress/danger to others. The former is a nested argument of course and doesn't really apply to the limit setting.

For many roads, the limits are set incorrectly, but it still can still be reasonably expected - by other road users - for drivers to abide by it (hence the need for the speedo). For today’s policy, the fundamental fault is the setting of the limit.

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PostPosted: Fri Oct 30, 2009 14:52 
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The Rush wrote:
SafeSpeedv2 wrote:
Apart for neigh all the points made above .... although we could take a query into the differences of friction that water and air have ! :) ...
Speedo check are only 'necessary' to aid knowledge of stopping ability, as part of the build up of collective information needed as we travel along.
Learning what speed one is traveling at (apart from legal compliance), helps to enable a fuller picture of information that helps us learn to judge from different aspects.
So the distance 'clear' in front of the car needs to be enough, to know that we can stop in, allowing for all possibilities (of hazard), so understand how fast one is traveling helps our judgment of the overall risk management - all necessary to drive safely.
We can of course drive safely without the 'need' of any speedo. One can drive better and more precisely with speedo and revometer, working together, to provide better control of the engine input / output. (Sorry tired and could better phrase this I am sure)!
In a related fashion, I remember when I used the speedometer as a tool to compare turning entry [and I suppose exit] speeds, and thus calibrating my internal lateral 'g-meter' (below 9MpH=slow/tight;, 10-13MpH=normal; 14-17MpH pushing a bit, 18+ pushing hard/wide). ('Slow in' permits 'fast out'.)
Lacking here is the ability to numerically measure the tightness/looseness of the turn.

Which makes me wonder ... If the speedometer can be a learning tool, could a longitudinal/lateral accelerometer also become one? Perhaps there would be benefits to including numerical accelerometers to vehicles other than high-end sports cars?


Dunno. I have a lateral accelerometer that I can easily move from car to car. In fact,I also use it for sitting on! :wink: Only thing is, it doesn't put numerical values on what it measures. I still find it useful though! The "geeky" side of me (or maybe that's "nerdy" - can never quite remember the difference!), would like to see something that gave numbers, but I'm not at all sure how useful it would really be. Much like a speedo, I have an inbuilt one (we all do!) but it doesn't talk in numbers. I think it's calibrated in units of "risk" but I'm not sure. It's interesting to note that it's rare to find a speedometer in a racing car, so I'm not at all sure how useful it really is in aiding our knowledge of stopping (or, indeed, cornering) ability. The big problem is that what we want to know is "can I safely stop / get round that bend"? All a speedo can tell us is how fast we are going. Now clearly there's a correlation between the two, but the speedo knows nothing about other relevant factors. The "I can get round here at 50MPH" school of thought could almost be argued as potentially having a DETRIMENTAL effect on road safety because one day, we'll try it when there's a diesel spill or a bit of ice. On balance, if I had to cast a vote right now, I'd be inclined to say that a speedo, as a road safety aid, can perhaps do as much harm as good! Didn't we once discuss whether or not we'd drive faster or slower if we didn't have speedos? Removing the speedo would force us to take decisions on what was a "safe" speed by using other inputs available to us - a bit like a blind person whose other sense become much sharper when deprived of sight???

As an "aside", (sorry for the topic drift!) , I was wondering,following Rush's comment about cruise control, whether it would be easy with modern "CAN-controlled" cars, to have cruise controls that you could set to maintain a particular fuel consumption, rather than speed? or a particular ETA? Probably not a good thing for road safety or traffic flow, but I bet it would be easy to do!


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PostPosted: Fri Oct 30, 2009 17:39 
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Steve wrote:
For many roads, the limits are set incorrectly, but it still can still be reasonably expected - by other road users - for drivers to abide by it


Slight deja vu moment viewtopic.php?f=14&t=18126&p=177715&hilit=pedestrian+speed#p177715

toltec wrote:
I simply base this on the idea that other road users, especially non-drivers, should reasonably have an expectation that vehicles will be travelling at around the posted limit.


The Rush wrote:
Which makes me wonder ... If the speedometer can be a learning tool, could a longitudinal/lateral accelerometer also become one? Perhaps there would be benefits to including numerical accelerometers to vehicles other than high-end sports cars?


You do not really want to be looking at an instrument mid-corner, whatever it is, if you are going so fast that the information becomes important, e.g. what lateral g you are pulling at the limit of grip, then you probably need to be concentrating on keeping the car on the road. I think Mole is correct in using his own kinaesthetic sense as a g meter because it is often not the value but how it is changing that is important.

I might just let you have one if it projects a vector arrow in a head up display that changes in length and colour rather than displaying a number and then generally only to be used in controlled training conditions rather than on the road. :)

Taking that idea a little further, how about a line strip projected in the hud in front of the car colour coded to show thinking distance and stopping distance at moderate and emergency braking levels? It could show dry or wet lines possibly depending on external sensors, it should still be a training tool though, the equivalent of cycle stabilisers rather than a long term driving aid.

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PostPosted: Sat Oct 31, 2009 10:13 
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toltec wrote:
... I think Mole is correct in using his own kinaesthetic sense as a g meter .


Nah! I was talking about me ar5e!

Jokes aside, I like the vector arrow / coloured display. I wouldn't mind betting that the manufacturers would be dead scared of bringing out something that would leave them open to get their butts sued if the vehicle encountered a set of conditions (diesel spill?) outside what was programmed.


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 Post subject: Re: Speedos
PostPosted: Sat Oct 31, 2009 14:08 
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Frequently!
So I can allow those other drivers who are sharing the road with me some form of idea of how to predict the fastest rate at which I will approach or recede from them.

Self choice with a self imposed choice of a "safe speed" :roll: removes the predictability, in speed, of the behaviour of others. That method of speed management is, I firmly believe, not safe at all.


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 Post subject: Re: Speedos
PostPosted: Sat Oct 31, 2009 14:53 
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Quote:
Frequently!
So I can allow those other drivers who are sharing the road with me some form of idea of how to predict the fastest rate at which I will approach or recede from them.


A good driver never assumes that the speed of any approaching (or receding traffic) is within any limit. A good driver would use their power of observation to determine the approach speed of any trafiic....but then you wouldn't have know that, probably!

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My views do not represent Safespeed but those of a driver who has driven for 39 yrs, in all conditions, at all times of the day & night on every type of road and covered well over a million miles, so knows a bit about what makes for safety on the road,what is really dangerous and needs to be observed when driving and quite frankly, the speedo is way down on my list of things to observe to negotiate Britain's roads safely, but I don't expect some fool who sits behind a desk all day to appreciate that.


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 Post subject: Re: Speedos
PostPosted: Sat Oct 31, 2009 15:07 
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GreenShed wrote:
Frequently!
So I can allow those other drivers who are sharing the road with me some form of idea of how to predict the fastest rate at which I will approach or recede from them.

Setting a limit needlessly low will encourage drivers to drive in a what other road users will view as non-predictable.
Using cameras on such roads will result with a disproportionate level of driver distraction.


Safe Speed campaign pages wrote:
Contrary to some ill informed opinions Safe Speed welcome properly set speed limits, and welcome speed limit enforcement when speed limits are exceeded in a way that causes danger.

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 Post subject: Re: Speedos
PostPosted: Sat Oct 31, 2009 18:24 
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Steve wrote:
GreenShed wrote:
Frequently!
So I can allow those other drivers who are sharing the road with me some form of idea of how to predict the fastest rate at which I will approach or recede from them.

Setting a limit needlessly low will encourage drivers to drive in a what other road users will view as non-predictable.
Using cameras on such roads will result with a disproportionate level of driver distraction.


Safe Speed campaign pages wrote:
Contrary to some ill informed opinions Safe Speed welcome properly set speed limits, and welcome speed limit enforcement when speed limits are exceeded in a way that causes danger.

There is no evidence of this but nobody will stop you guessing and claiming so.


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 Post subject: Re: Speedos
PostPosted: Sat Oct 31, 2009 18:31 
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Quote:
There is no evidence of this


Evidence of what exactly? People ignoring ridiculously low limits?

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My views do not represent Safespeed but those of a driver who has driven for 39 yrs, in all conditions, at all times of the day & night on every type of road and covered well over a million miles, so knows a bit about what makes for safety on the road,what is really dangerous and needs to be observed when driving and quite frankly, the speedo is way down on my list of things to observe to negotiate Britain's roads safely, but I don't expect some fool who sits behind a desk all day to appreciate that.


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 Post subject: Re: Speedos
PostPosted: Sat Oct 31, 2009 18:48 
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GreenShed wrote:
There is no evidence of this but nobody will stop you guessing and claiming so.

My understanding is that this campaign supports targeted enforcement of properly set speed limits by real-life traffic police officers, but opposes the system that prevails at present of sending a fine in the post and expecting drivers to incriminate themselves. But enforcement must always have the objective of improving safety rather than being done for its own sake.

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 Post subject: Re: Speedos
PostPosted: Sat Oct 31, 2009 18:55 
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GreenShed wrote:
Steve wrote:
Using cameras on such roads [with needlessly low limits] will result with a disproportionate level of driver distraction.

There is no evidence of this but nobody will stop you guessing and claiming so.

There's guessing and there's logically deductive reasoning - trust you to try to spin this as the former :roll:

A lack of evidence doesn't mean it doesn't exist. Were you/the SCPs saying such a thing about RTTM before that illusion was proven?

Mind you, a recent HA report stated that (a group of) drivers on average had an average time between (speedo) glances of about 11 seconds at motorway SPECS camera sites [table 7, speed cam tech at roadworks] - that's time spent with attention away from the motorway (disregarding looking at the cameras themselves). Can you really say that level of distraction is typical on normal stretches of motorway? Every 11 seconds...?

Would you say it is impossible/unreasonable that drivers will look at speedos more when driving on camera enforced roads where the speed limit is set needlessly low, in order for them to regulate their speed slower than they would have otherwise driven?
If not, and there's no study regarding this, should you be questioning why such evidence doesn't exist after so many years? Surely such a simple thing cannot be beyond the means of the large, full-time 'professional' and multi-million pound funded departments like the DfT, SCPs, TRL, HAs?

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 Post subject: Re: Speedos
PostPosted: Sat Oct 31, 2009 19:59 
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GreenShed wrote:
Safe Speed campaign pages wrote:
Contrary to some ill informed opinions Safe Speed welcome properly set speed limits, and welcome speed limit enforcement when speed limits are exceeded in a way that causes danger.

There is no evidence of this but nobody will stop you guessing and claiming so.[/quote]

I think you need to be far more specific ?
Be happy to answer once I know to what you are referring.

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