Acceleration. That which enables you to have a longer rest at the next red light.
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Acceleration. That which enables you to have a longer rest at the next red light.
Nothing worse for a heavy truck driver than the car driver that coasts to a set of lights or starts to brake 100 - 200mt from the traffic lights, you have 4 or 6 gears to change I have a total of 16. As for speeding I don't because I can't. governed engine, drive line. as well I can't see the reason to exceed the posted limit for the section of road. IE From Mackay to Nebo at 10 km over the posted limit will only save you 6min. from Mackay to Rocky at 10km over the posted limit will only save you 36min. this is with a clear run, no traffic works or slow drivers. IS IT WORTH IT !!!
Well all these things have to be done with current conditions and traffic in mind of course, but surely the principle is even more relevant when so many gear changes are involved? Knock off a little speed and go back a gear or two or even three has got to be better than stopping and then going back up through 16 gears. Maybe I'm missing something but I can't see how the size of the vehicle or number of gears changes the basic premise - delay getting there and by the time you do get there you don't have to stop - just cruise on through.Quote:
Originally Posted by Opelblues2
But what about the people who are behind you who may not need to stop? How about the scenario where there is a right turn lane and the right turn arrow is green but the cars behind you cannot reach the right turn lane in time to go around because you are cruising along slowly in front of them because you don't want to come to a complete stop? I bet they would be cursing you. Same thing with a "turn left anytime with care" lane.Quote:
Originally Posted by FenceFurniture
That type of driving causes far more inconvenience to other road users than what you perceive it saves you.
Cheers
Doug
I repeat:
Quote:
Originally Posted by FenceFurniture
And...
it is no different to what Bob was saying about the speed limit. Nobody is compelled to drive at the limit, so me slowing down a tad is no different to another person travelling at that lower speed consistently. In other words, if it's that important for a car behind to get to the lights quicker then they can go around. If it's a single lane road - well nobody is a mind reader and knows what the intentions of the car behind are.
Having said that, if they have a right blinker on, and I can see that it will inconvenience them that I'll do what I can to minimise that, but I won't go hugely out of my way. I'll accommodate what is feasible at the time.
Actually Doug, the kind of driving that you are perceiving there describes a mate of mine to a tee. He-could-not-care-less about other drivers, and is obsessed about fuel economy. He'll ease off the accelerator before the crest of a hill so that he just craaaawwwls over the crest (out of gear of course) and then coasts down the hill. If it's a big hill he will then zip past all the people he has just held up (because they have gone around him in frustration) and then hold them up on the next hill.Quote:
Originally Posted by doug3030
A giant PITA on the road. His methods are fallacious in many ways - he just doesn't understand thee concept of dropping back a gear at the base of an uphill (where the revs are up) and easing off the accelerator. Far more fuel efficient than squeezing the accelerator down to get the maximum out of top gear until the engine is labouring and then changing down halfway up the hill. He's just got a mindset that staying in the highest gear (regardless of accel pedal depression) must be more fuel efficient. Same thing with driving out of gear - must be more efficient, regardless of how dangerous that can be, and how totally unprepared he is to take evasive action (we have to drive allowing for the other dickhead - defensive driving). Until reasonably established otherwise, I assume the other drivers around me could be incompetent.
These days, with him, I usually insist that I drive. It's too embarrassing and frustrating being his passenger. And I'm saving him fuel over his dopey methods.....
Sounds like my ex-brother-in-law. I had my niece, his daughter (primary school age) in my car once and the conversation went something like this:Quote:
Originally Posted by FenceFurniture
Niece: You drive up to the red lights and stop. Dad slows down and tries to avoid stopping. Dad says that makes him a better driver than you.
Me: Really? Well I think I am a better driver than your dad.
Niece: Why?
Me: For exactly the same reason.
Niece: What?
Me: Well, next time your dad slows down like that for a red light, have a look at the drivers who go past and turn off to the left or right. See if they are mouthing insults at your dad. He is slowing them down, they might not have to slow down if he drove sensibly.
(a few weeks later)
Niece: Uncle Doug, you were right. The other drivers are always giving dad dirty looks.
The Brother-in-law was absolutely obsessed with not coming to a complete halt at lights and really did annoy people, but he could not see what a problem it was for others. I was in his car once when someone else did the same thing to him when he wanted to turn on the green arrow. He cursed and swore at this driver and said they should not even be on the roads. It never occurred to him that they were doing the same thing as he does.
Cheers
Doug
Yeah, so am I to an extent.....Quote:
Originally Posted by doug3030
.....but without this bit:
Quote:
Originally Posted by doug3030
Here's something few people know about.
Lets say the speed limit on a freeway is 100 and the traffic density is high but not yet grid locked .
What is the optimum speed for the roads to transfer the maximum number of cars ?
It turns out that if everyone sticks between 70 and 80 this will result in the shortest average time on the road.
For medium-high traffic density it's 80-90.
The speed limit only really results in a minimum time trip for medium to light traffic density.
The reason is that slower traffic results in less surging (fast - slow - stop) and cars being able to safely keep closer together.
The lane switchers and tailgaters that insist on trying to do the speed limit in higher traffic densities only slow things down not just for everyone else but for them as well.
This is major real reason for variable traffic speeds in places like Europe.
Interestingly this was being discussed today on Radio National's Future tense.
That makes absolutely perfect sense Bob - there is no point in trying to travel at very much more than the average speed of the entire journey. I've often wished (and said) that people should drive with ant mentality, particularly when it comes to merging - one from the left, one from the right, with everybody reducing their speed beforehand to the speed they will need after the merge. When was the last time anyone saw a traffic jam or pile up on an ant trail? Err, without the aid of insecticide. :;Quote:
Originally Posted by BobL
But no, what we get is the fwits that drive up as far as they can in the lane that's ending, thinking that because they're 4 car lengths further up they've made REAL PROGRESS, when all they have done is forced other people to stop upon their insistence - and slowed their stupid selves down as a result..
Whenever I see traffic entering from the left (particularly on a motorway), and I'm in the left lane, I immediately switch to the right lane if possible. It's just sense - I don't have to slow down and neither do those that are entering.
Sorry if we are getting a little off track Mark (OP), but it's all pretty relevant I guess.
Going back to my red light strategy for a moment: I remember one one night coming home from afternoon shift (so about 11 pm or so) from Sydney CBD in the mid 1970s. I was getting an absurdly good run with green lights which is quite miraculous in Sydney at any time of the clock. It became a game for me, so I decided to see how far I could go without actually stopping. In the end it was about 20km. Perhaps this was when I started developing my slow down in advance technique. :U
Are we talking about transferring the maximum number of cars or about an individual car reaching its destination in the shortest possible time?Quote:
Originally Posted by BobL
Lets look at optimum speed to transfer the maximum number of cars first. Lets make a huge assumption that everyone is following the accepted guidelines of leaving 2 seconds travelling time between their vehicle and the one in front of them. to make the maths simple lets assume that the distance is measured from the centre of the car to avoid complicating the equation by the length of the vehicle.
Based on that assumption, it does not matter how fast they are going, the road will allow passage for the same number of cars per hour.
Taking it a stage further and allowing for the vehicles to have length, then obviously, the faster the vehicle goes, the less time it takes to travel its own length, so the faster they are travelling the more vehicles will be able to traverse a given length of road. One point for travelling faster.
Now for the shortest average time on the road: Its a no-brainer isn't it? The faster you can go the sooner you get there. We hear people say "It took a while to get here because the traffic was bad" have you ever heard someone say "It took a while to get here but the road was actually transferring the optimum number of cars". I have never heard anyone say that or even care about that. I do not know any traffic engineers or town planners.
If people are travelling in a 100km/hr zone and doing 70 or 80 instead of 100 surely it is because that stretch of road will not support that volume of traffic travelling at the posted speed limit. We get this on a daily basis in Melbourne, and I am sure in most other large/capital cities. Saying that you will get there faster by sitting on 80 instead of 100 is just government spin doctoring. The solution is to upgrade the roads, not to lie to the people. Not all of us are stupid.
Cheers
Doug
Well ExKEEyuse me - speak for yourself. :DQuote:
Originally Posted by doug3030
Well if you cannot identify with NOT being stupid its not my fault :D :D :D :2tsup::2tsup: :2tsup::2tsup:Quote:
Originally Posted by FenceFurniture
(note excessive use of smilies. If I add many more the board will reject the post.)
Cheers
Doug
Hello DougQuote:
Originally Posted by doug3030
Now you do :)
Hi Ian, I certainly hope you are better than the one who does the work for our local council or you won't be getting any invites to my barbeques either :D :D :DQuote:
Originally Posted by ian
Cheers
Doug
I say employing some people to do *this* would be a reasonable use of speeding $$s
https://vimeo.com/122888442
I do not have a motor cycle but I have actually done similar things to people who richly deserve it. If we can get some funding I would apply for the job. :2tsup:Quote:
Originally Posted by pmcgee
Cheers
Doug
Ah, well just the man then Ian. Rather than keep going OT, perhaps you can help me here.Quote:
Originally Posted by ian
Yes it is about volume of traffic and we all experience that but it's more subtle than just the road not being big enough. In the US they tried to cope with congestion by just adding more lanes to the freeways and they found it did not help much. To get the traffic to travel at the speed limit during peak periods would require 10 -15 lanes which has its own problems not to mention the cost so there has to be a smarter way.Quote:
Originally Posted by doug3030
It is definitely not easy to explain but I'll give it a try. If you try to sit on 100 along with a substantial proportion of the other inconsiderate drivers who also insist (it's the goddam right after all) to sit on 100 the pack will indeed end up moving at 70. If everyone was to not do more than 80 then the average pack speed will indeed be more than 70. A single inconsiderate driver may indeed be able to average significantly more than this provided the other inconsiderate divers don't join that driver in attempting to travel at the speed limit. As soon as enough inconsiderate drivers start doing this the pack speed will drop as week as the individual drivers speed will also drop.
This has nothing to do with government spin doctors. Its a classic optimisation problem in mathematics. These mathematicians are paid big bucks to determine the optimum speed and sequence of all sorts of processes, computer programs, timetables, loading shipping containers, sequences of digging up ores, assembly of manufactured goods, traffic flow etc. They save businesses and governments billions of dollars a year. Modern society would collapse if these guys did not do their stuff. If you think this is peanuts and common sense just try reading the technical reports they put out - most of us are unlikely to even understand the paragraph let alone the text. Heres a link to a study of increasing average freeway on ramp speeds http://www.me.berkeley.edu/~horowitz...M_TRR_2011.pdf
Some of these problem was tackled many years ago. It's a failure of governments to implement their recommendations which has lead to greater congestion than necessary. Look at how long it took to automate traffic lights for major minor road intersections to give a time priority to the major road and that one was common sense.
The lower speed does indeed sound stupid but it has been demonstrated in places like Germany where they usually have unlimited speed limits on freeways. They installed variable speed limits on some sections of their autobahns near major cities and by imposing a speed limit of 130 or 80 or whatever they got more cars through per hour than they did when it was all open speed limit. If anything the spin doctoring centred around too high a traffic density making it too dangerous for open speed limits in the situations but the traffic engineers were more interested in getting more cars through.
Here is another one that has been studied in great detail. When two major freeways meet at higher traffic density, vehicle merging can be a nightmare. The degree of congestion is largely controlled by the drivers that insist on doing the speed limit. This leads to massive stop start driving and the inevitable Crawl. If the speed limits are dropped by 20 kph more cars get through in the least possible time. This is now commonly used in European freeway junctions.
And the ants have had it nailed for millions of years, god bless 'em.Quote:
Originally Posted by BobL
I'm not going anywhere near that link of yours Bob - it'll fry my brain and I'm just off to beddiebyes.
about 60km/h, but the actual "optimum" speed varies depending on the lane width, the number and size of trucks, trailer and caravans in the traffic stream, the number of traffic lanes, the spacing of entry and exit ramps and the volume of traffic entering and exiting, the horizontal curvature, the vertical grade AND the experience of the drivers -- do nearly all of them drive the route at that time every day, or is the traffic situation new to them?Quote:
Originally Posted by BobL
these people have the most negative impact when the traffic is still relatively "light" -- for peak hour conditions.Quote:
The lane switchers and tailgaters that insist on trying to do the speed limit in higher traffic densities only slow things down not just for everyone else but for them as well.
If I can find it, I'll post the plot we did a few years ago of the speed / volume data from a 80km/h road
Yep it's complicated.Quote:
Originally Posted by ian
There ya go!Quote:
these people have the most negative impact when the traffic is still relatively "light" -- for peak hour conditions.
GoodQuote:
If I can find it, I'll post the plot we did a few years ago of the speed / volume data from a 80km/h road
Driving.... is that state of mind where everyone else is wrong...
Ever noticed how slow at reacting that driver is at the head of the queue when the light turns green?Quote:
Originally Posted by Ari2
Then the way the drivers behind dawdle and fail to keep up
They must be the main reason I'm always catching red lights! :D
Of course, your car first has to actually make it onto the road! :hihi:
https://www.youtube.com/watch?v=PGMUGjlV5HU
Hi BobQuote:
Originally Posted by BobLGoodQuote:
Originally Posted by ian
Here it is
Data is from Lane 1 of a two lane access controlled road in Sydney. I better not say which one.
Each data point represents the total number of vehicles using the Lane in an hour, plotted against the average speed of those vehicles. Data was collected over 4 "normal" weeks -- i.e. no public holidays, no school holidays in the period.
The traffic stream contains a significant number of very heavy vehicles which is reflected in the relatively low maximum volume.
You can readily see the interrelation of speed, volume and transit time and how the real world data matches the "model".
[QUOTE=ian;1852736]You can readily see the interrelation of speed, volume and transit time and how the real world data matches the "model"./QUOTE]
Hi Ian,
Just trying to make sure I understand your graph. The dots represent a plot of volume per hour and average speed? Does the dot, for example aligned at approximately 65 Km/hr on the vertical axis and aligned with about 700 vehicles on the horizontal axis represent a period of an hour's duration when 700 vehicles passed along the road at an average speed of 65 km/hr? Or is it longer or shorter time periods that are adjusted to vehicles per hour for consistency of data plotting? Or is it something completely different?
Doug
Great - thanks for that.Quote:
Originally Posted by ian
Good to see a real local example.
The ones I have seen have all been US or European but they are pretty similar.
ADR's to my knowledge have always specified a speedometer that reads over?? Any links to where it was otherwise??Quote:
Originally Posted by doug3030
To save any confusion the ADR's specify that the speedo must be reading more than the actual road speed within a set tolerance.
thanks BobQuote:
Originally Posted by BobL
the important thing about that chart is that it the data represents real vehicles -- more normally the chart is expressed as passenger car units (PCUs)
PCU data is adjusted up by adding notional cars to the total vehicles by converting trucks to an "equivalent number" of cars.
The factors involved are too arcane for this discussion.
Hi DougQuote:
Originally Posted by doug3030Hi Ian,Quote:
Originally Posted by ian
Just trying to make sure I understand your graph. The dots represent a plot of volume per hour and average speed? Does the dot, for example aligned at approximately 65 Km/hr on the vertical axis and aligned with about 700 vehicles on the horizontal axis represent a period of an hour's duration when 700 vehicles passed along the road at an average speed of 65 km/hr? Or is it longer or shorter time periods that are adjusted to vehicles per hour for consistency of data plotting? Or is it something completely different?
Doug
each data point represents the number of vehicles crossing the detector in 1 hour -- there are 24 records for each day each of 1 hour duration, the first starting at 1 second after mid-night and running through to 1:00AM
vehicles is the total number of VEHICLES crossing the detector in that hour.
average speed is the average speed of all vehicles crossing the detector within that hour.
Now a count of 700 vehicles in an hour could represent 500 cars and 200 trucks. Depending on a bunch of arcane factors, one big truck might be equivalent to 5 cars, so the 700 VEHICLES might be equivalent to 1500 Passenger Car Units (PCUs).
For the work we were doing at the time, grossing trucks up to PCUs wasn't necessary.
Is this permitted - confusing arguments with facts??
As we all know, gut feelings and personal hobbyhorses are much more reliable.