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What could be done to combat speeding on our roads?

Deborah-Claire McKenzie


There have been many reports of motorists using the lack of traffic on the roads during the Covid19 lockdown to flout the speed limits and now with more traffic back on the roads there is a danger that some may continue to drive at excessive speeds even after things are back to ‘normal’.


Behavioural Science in transportation (understanding the behaviour and motivations of transport users such as motorists and rail commuters etc) is a fascinating subject which plays a big part in the engineering and design of roads and their ‘furniture’ in an attempt to gently persuade drivers to modify their driving behaviour to something more appropriate. 


There are many such psychological tactics in place to combat speeding but could we be doing more? What other engineering solutions could be implemented to stop excessive speeding? How do different countries tackle speeding on their roads? What could we learn from them? 

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    Youngsters can get reduced insurance if they install Telematics.

    The youngsters that TWOC cars, rag them around and get into police chase need dealing with far more robustly.

    The narrative that is pushed is that everybody are bad drivers which is so far from the truth when you factor in how many millions of miles are driven every day without incident, in fact some drivers are extremely good having been professionally trained on the track and skid pans etc.

    Many drivers, mainly men, really enjoy driving and engage totally with the experience and the vehicle, others just do it as a means to an end and do not engage at all and are mentally in a completely different place.

    Speed does not kill, it is only a part of the equation and a small part at that.
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    Andy Millar:
    Denis McMahon:

    Have braking distances improved over time? I am not so sure. However good the driver or the brakes, ultimately it depends on the coefficient of friction between rubber and asphalt. Since this is a fairly innate physical feature, my guess is that it has not improved by much. I should be very interested if anyone has any reliable data on this. It is probably sensible to stick to the long-established figures for braking to stay on the safe side.




    Oh gosh yes they've improved. First disc brakes and then ABS were quantum steps in braking improvement. But whether braking distances have improved significantly in, say, the last 30 years I'd agree is perhaps more open to question. They probably are improving incrementally due to improvements in tyres, road surfaces.

    . . .

    Just found this article https://www.diaryofanadi.co.uk/?p=21456 which in turn refers to this one https://www.howardsgroup.co.uk/news/group/stopping-distance-is-the-highway-code-wrong which have a range of strong viewpoints and calculations on this issue.

    . . .

    However, I very strongly suspect that the excellent braking of modern cars gives a false sense of security, and may well have caused drivers to drive faster without full awareness of the observing and thinking time factors.


    Cheers,


    Andy




    Yes, Andy, brakes certainly have improved. Disc brakes avoid the fading effect of drum brakes. ABS prevents wheel lock, i.e. skidding, and avoids reliance on the skill of the driver to apply "cadence braking" or whatever. Tyre improvements seem to be mainly in tread pattern design. This is designed to maximise removal of water in wet conditions, and probably has little effect in dry conditions.


    I have visited the web sites you suggested and studied them with interest; I've bookmarked the ADI one for further reference since it is a useful guide to all sorts. Although there are calls for revision of the Highway Code advice on stopping distances, there is unfortunately no real data or theory to back this up. I did say earlier that coefficient of friction was very relevant and was seeking information on how this has improved over the years. Such information has not been forthcoming so far so I did a bit of "digging" myself. The following web sites are relevant and interesting.

    www.engineersedge.com/coeffients_of_friction.htm
    hpwizard.com/index.html
    www.engineeringtoolbox.com/friction-coefficients-d_778.html


    The overall consensus seems to be that the coefficient of friction between rubber and asphalt varies between about 0.6 and 0.9. The latter figure applies to non-skid braking in dry conditions; the lower applies to skidding during braking or to wet conditions. Another interesting web page is:

    en.wikipedia.org/wiki/Braking_distance


    From here I quote:

     



    . . . The braking distance is one of two principal components of the total stopping distance. The other component is the reaction distance, which is the product of the speed and the perception-reaction time of the driver/rider. A perception-reaction time of 1.5 seconds,[2][3][4] and a coefficient of kinetic friction of 0.7 are standard for the purpose of determining a bare baseline for accident reconstruction and judicial notice;[5] most people can stop slightly sooner under ideal conditions. . .



    So it is beginning to appear that coefficient of friction is around 0·7 for realistic conditions, and better than this in ideal conditions. In the absence of any sound data about how this may have improved over the years I decided to tackle this slightly differently. How well do current figures for friction relate to the traditional Highway Code values? Let us see.


    The general equation relating distance, velocity and acceleration is

    v² = u² + 2as, where

    u = initial velocity,
    v = final velocity,
    a = acceleration,
    s = distance travelled.


    Since we are analysing braking to a standstill, v = 0 so the equation becomes


    0 = u² + 2as. Transposing:

    u² = -2as.


    The minus sign indicates that acceleration is acting in reverse direction to motion (i.e. deceleration).


    Find a.

    a = -u² /2s.


    Let us apply Highway Code figures to this. (It is countless years since I last did an analysis in imperial units but here goes.)

    u = 30 mi/h = 44 ft/s.
    s = 45 ft (as given).

    So the equation becomes:

    a = -44² / (2 x 45) = 21·4 ft/s².


    If the coefficient of friction were unity the acceleration would be equal to that due to gravity, i.e. 32·2 ft/s²


    So this deceleration represents a coefficient of friction of 21·4 / 32·2 = 0·66.


    This is pretty similar to the figure of 0·7 discussed above.


    My view is that the Highway Code figures for braking distance are still fairly realistic, and include some allowance for skidding and less-than-perfect conditions, but perhaps we should consider increasing the thinking distance.


    I disagree with the suggestion that we should increase the thinking distance by making speed in miles per hour represent metres instead of feet. As I keep saying, mixing imperial and metric causes confusion. (As is happening in this very discussion) We should instead be looking towards metrication of distances and speed limits on our roads. Meanwhile, if we want to offer extra thinking distance, simple double or triple the speed in miles per hour.


     

     


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    i suggest you need the driver to feel some sense of danger - modern cars go to great lengths to remove this.

    (having started driving in old cars in the last century, I very much agree with the comments about how much better modern cars are.)


    So, how to re-create the feeling of mortality associated with driving an all drum brake car with cross ply tyres on a wet road, in a pre-seat belt car  ? (and possibly a significant rust hole in the floor under the pedals and a dicky starter motor so you have to park downhill on a slope so you can roll start. That bit may have just been me of course.)


    Perhaps above a critical speed a row of spikes should emerge from the dashboard and the driver's seat belt be removed  ?


    Setting the speed limits  also needs an input from what is an acceptable fatality rate - if we are being shown folk dying on TV every night from a horrible virus, at a rate of some hundreds per day, so we are all doomed, it is not so surprising that the other half of the equation says it makes little sense to worry about the speed limits unless the death rate associated is comparable or higher. so for example we could raise the speed on motorways until it is.


    Mike.
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    mmm the 40/50 yr old experienced drives  fast ??? that's interesting , but we know most serious accidents involve young and inexperienced drivers who are also driving fast , and then we have driving fast due to intoxication , which we are not clear about is old or young. 

    ok good thing there for analysis, but I still feel people should drive , and I don't think the driverless car will help much, not a very scientific answer , I admit but just feel , the driverless car will lead to a lot of job losses.
  • 0
    good evening,

    The two major causes of road accidents are: the human factor, ie drivers and pedestrians, and the infrastructure factor - the roads and, to some extent, the mechanical condition of the vehicle. The human factor - the dominant one of the other factors Most accidents occur because of negligence, a lack of judgment, irresponsible driving and the like. These are non-compliance with self-risk and self-driving traffic laws on the road, driving under the influence of alcohol or drugs, driving fatigue and lack of concentration, distracting actions from the road (using a cellphone without a handsfree, reading documents, looking back, etc.). Usually these are the causes of fatal to fatal accidents, which result in fatalities. But even ordinary drivers, without awareness and alertness and lack of driving culture, are sometimes involved in accidents. In addition, the speed of response of the driver and his decision-making ability in various risk situations greatly influences his chances of being Involved in car accident. But holding the steering wheel is not the only fault. Pedestrians who unexpectedly break into the road, or cross a road in a forbidden place, as well as two-wheeler riders of the type who do not obey traffic signs or traffic lights, are also part of the human cause of traffic accidents. The infrastructure factor Many roads across the state are considered high-risk roads. These are usually roads that were paved decades ago and have not been adapted to modern transport needs since. Usually these are narrow roads, in many cases with very narrow margins, with no separation means and dilapidated maintenance. Some are defined as "red roads", ie roads with a rich history of fatal road accidents. The constant increase in the number of vehicles moving on Israeli roads increases the volume of traffic and loads on the major traffic routes, This is necessarily reflected in the increase in the number of accidents. In recent decades, the Ministry of Public Works (now called the National Society) has been operating Roads) to improve and expand those narrow and dangerous roads, some of which are major transport arteries. The main problem: pace The works do not catch up with the growth rate in the number of vehicles. Government ministries are also involved in the development and construction of the New inter-urban roads, with the aim of reducing traffic congestion and increasing road safety.
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    Israeli roads?  Why the reference to Israeli roads?
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    Because I want to share what happens to us.

    I think my father in the forum knew.
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    Rob Eagle:

    Israeli roads?  Why the reference to Israeli roads?


    Well, the original question only referred to "our roads", without actually specifying a country.  It all depends on where the writer is.


    But why does it matter? Would you assume that what other countries do can tell us nothing about what we should do in the UK?


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    Hi All


    Just popping in here to remind everyone that there are many IET Members and engineers for whom English is not their first language so intended meaning can sometimes be lost in translation. May I please ask everyone to be mindful of that and also our Rules of Conduct 


    Also, the OP has specifically asked for examples from other countries around the world as to how they combat speeding:

     
    How do different countries tackle speeding on their roads? What could we learn from them?



    so contributions to this topic with such examples are very welcome. ?
  • 0
    Good morning Lisa, 

    thank you so much, you are lovely

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