A bit surprised it seems to simple and yet ufeusl.
By: Gordon Pye
Date: Saturday, 09. December 2006
To use fuel efficiently, the driver of a heavy vehicle needs to store the energy contained in the vehicle. Traffic calming is perhaps the greatest waste of fuel ever devised. One new roundabout, causing an average speed reduction of 30 Kph, traversed five times loaded at 32.5 tonnes, and four times at 11.5 tonnes, used on average 2 gallons extra fuel per day. This can be proved by mathematical calculation, but I have never seen the equations in any text book.
I have undertaken a rough calculation of the extra fuel used by causing a heavy vehicle to stop or slow. The roundabout calculation shows that fuel consumption is doubled over a certain road section from the start of braking, to the end of acceleration. This will be true for all vehicles forced to stop or slow. The same principle applies to all vehicles if the stored energy has to be wasted through the brakes.
I have recently heard that all new or improved major roads in Lancashire must have roundabouts at all junctions with less than 1 km vision in both directions. The roundabout recently constructed on the A59 near Clitheroe is so tight for Heavy Goods Vehicles (HGVs), that it will reduce speed to under 20 Kph for vehicles traveling up grade. It is also guaranteed to increase congestion, therefore using extra fuel. Even though the road is dual carriageway, the roundabout has only one true lane through it, unless everyone drives a Nissan Micra.
If anyone had deliberately set out to design a death trap for cyclists, it is doubtful whether they could have made a better job of it. Drivers at a nearby cement works are experiencing vehicle stability problems at low speed in the eastbound (empty) direction. Their union representatives have asked the company to contact the local highway authority in an attempt to get the roundabout modified into a safer layout.
Miles per Gallon is not a true measure of fuel consumption. The true measure is grams per kilowatt hour, as used by transport engine manufacturers. The total amount of time under power is the factor which determines Mpg. Almost all internal combustion engines are most efficient at or near full load. This is because the heat lost through cooling and the exhaust is almost constant under any load condition.
Developments such as power steering, air conditioning and even electric windows all consume extra fuel. Air conditioning is perhaps the most environmentally damaging development, as it consumes a vast amount of extra fuel. Average family cars fitted with power steering may use up 10% more fuel than non fitted vehicles. The addition of air conditioning may increase fuel consumption by a further 15% or more?
Factors such as these can make recent theoretical improvements in thermodynamic and emission performance quite meaningless. Almost all new cars come with power steering and or air conditioning as standard. If the public were aware of the extra pollution caused by these extras, perhaps the manufacturers would be forced to abandon them as standard.
Road safety is usually the reason used to justify traffic calming schemes, but most are designed to slow the average family car. To the HGV driver, most new junction layouts cause more potential safety problems than the ones they replaced. Road design appears to have more to do with the need to accommodate standard kerb (curb) components, than the physical needs of long vehicles. Modern road design takes no account of the turning space that a long or articulated vehicle needs. The junctions and roundabouts are quite adequate for the needs of a car, but the lanes are usually impossible for HGV's or buses to follow. Apart from causing additional safety problems for other road users, bad road design also increases wear and tear, driver fatigue, and thus the ultimate safety of the vehicles themselves. I have been reliably informed that new traffic calming under rail bridges is largely responsible for the recent high number of bridges hit by high vehicles? The present situation is probably the result of a whole generation of road designers being taught the perverse theory that, "making roads more dangerous makes them safer."
Inappropriate traffic calming on routes frequently used by HGV's and buses causes additional problems. Once wide roads which once caused few problems are now filled with pinch points and traffic islands. Most new roads are a series of traps to catch cyclists and incompetent car drivers.
The specified minimum safe distance from the kerb was 18 inches when I passed my HGV test in 1982 . This distance is impossible to achieve where traffic calming measures exist. Traveling close to the kerb is bad for pedestrians, especially when pools of water form in holes or hollows.
The A59 at Copster Green between Preston and Clitheroe carries a large amount of extra HGV traffic from the cement works and roadstone quarries at Clitheroe, and the quarries in the Craven area of North Yorkshire. The road was improved during the 1960s and did not require resurfacing until about 1990. Two years ago, Lancashire County Council introduced traffic calming measures at Copster Green. In addition to a 40 Mph speed limit, several traffic islands were built into the centre of the wide road.
Since the introduction of central traffic islands, all HGVs are forced to travel close to the nearside kerb. This has caused excessive damage to the nearside of the road in both directions. Almost all the drain grates have been pounded well below the road surface and the surface is cracking up next to the kerbs. This creates additional dangers for cyclists.
In just a couple of years, the traffic islands at Copster Green have caused the same amount of damage which one would expect after about 15 years or more for a similar wide road. The extra maintenance of the carriageway must place extra demands on natural resources. Patching roads usually means that more material than needed is ordered. The spare (usually at least a ton) ends up being tipped back at the quarry, unless the driver can find someone who has a use for it, then only if its the last load of the day.
Traffic Calming encourages lunatic drivers to attempt an overtaking maneuver on the approach to pinch points, or roundabouts . It is impossible for vehicles to follow a true safe line through any of the obstacles after the road alleged safety improvements. Road design is a major factor in overall road safety, but is seems as though no one is prepared to take this important factor seriously.
Many accidents involving goods vehicles are a direct result of poor road design. Adverse cambers and other ideas designed to slow traffic are built in to almost all new roads.
Road design appears to be immune from scrutiny by accident investigators, even though it is the probable cause of many accidents. Most new road junctions are designed to cut the speed of vehicles using them. However, designing roads with impossibly low safe speeds is counter productive in the case of heavy goods vehicles. Being crushed by a goods vehicle ( or its load ) traveling at 5 Mph leaves you just as dead as one traveling at 50 Mph. Modern road layouts almost all incorporate features which can set up a pendulum effect in high vehicles and lead to slow speed roll-over. The driver can counteract this effect by use of the accelerator to provide a force to cancel out the effect. Being forced to apply the brakes, or cut the accelerator at the wrong moment during the pendulum cycle is extremely dangerous.
Continual braking and accelerating also causes the brakes of HGVs to rapidly overheat and "fade" thus significantly increasing the stopping distance in an emergency. This factor is compounded on vehicles fitted with ABS, but that's another story.
Air pollution could also be reduced by reversing the present theory of traffic management by traffic calming. In many cases this would cost very little as it mainly involves altering the phasing of traffic lights. The replacement of all small diameter roundabouts on major roads would also produce a useful reduction in emissions from all vehicles. Part time traffic signals and "free give way" left turns could replace many current roundabouts and other permanently controlled junctions, without a significant reduction in safety.
The recent development of speed cameras offers a unique opportunity to depart from the use of potentially dangerous road layouts to control the speed of vehicles. Roads could once again be laid out to suit the true safe turning characteristics of vehicles, as demonstrated when snow obscures the lane markings. By getting rid of the need for small roundabouts and any other forms of traffic calming, land, fuel, tyre wear, and other vehicle maintenance is saved; road maintenance will also be less frequent and easier. Thus we would likely see cost savings for everyone and benefit to the environment all round.
Showing 1 - 9 comments
A bit surprised it seems to simple and yet ufeusl.
It would be good to get the overall Co2 equation on this.. especially in conjunction with poorly activated traffic lights... the cumulative effects of Co2 would be a considerable saving...for operators and the Govts committments to Co2 reductions..
bit of a glitch on the date format on some of the earlier articles - we are updating this so should be fixed soon...
Why have you changed the original publication date from 1996 ( corporate pressure ) ?
Fpr years I have considered why some responsible body doesn't challenge the theory of traffic calming (humps, chicanes,mini roundabouts galore) being to minimise accidents.
Isn't it the case that obstruction of the highway is an offence?
Don't traffic calming measures cause obstruction of the highway?
When will we see a challenge in the High Court, based on these thoughts?
The A59 through Copster Green is being substantially repaired and resurfaced yet again. The traffic calming installed there has reduced the life of the road surface by half the average for a section of similar road without traffic calming.
Simon from SoCal has obviously never seen the tight roundabouts installed in many UK trunk roads since the 1990s but I will give him some accommodation if he is talking about large diameter roundabouts. These were a feature of many 1960s road designs in the UK and allow all vehicles to maintain a reasonable speed through them. The one at the A59 / A671 junction at Whalley even has a free lane for straight through A59 traffic up the hill. Unfortunately space is at a premium on most UK roads and the fact that everything has to slow to a crawl must outweigh the possibility that some traffic will have to stop at a set of traffic lights. The better roundabouts for pedestrians and cyclists argument is a red herring as light controlled pedestrian crossing can be easily incorporated at traffic lights.
It would appear that green groups want to do everything possible to screw up road transport and maximise the take from their favourite fuel taxes. Whilst large roundabouts could theoretically cut the average time traversed at junctions with heavy slow moving traffic from all directions, here in the UK they are small roundabouts at lightly used junctions. If most of the traffic runs along the major road " Smart " traffic lights will use far less fuel from all vehicles as theoretically hardly any vehicles on the busy main road will actually need to stop. At many junctions it would be safe to have part time signals ( many busy roundabouts are already so fitted ) and therefore no need to stop or slow on the main road at all outside peak times. Of course part time traffic lights would need to follow railway practice and have some sort of preceding " distant signal " to warn drivers when they were likely to be on red.
Perhaps SoCal like many of the alleged experts trained in the universities has had his brains washed by the green lobby. Road design is rapidly becoming a quasi-religion. Only a few weeks ago " traffic managers " put lanes around a large roundabout at Lancaster with a kink in them to " slow HGV's down ". This is type of feature likely to induce slow rollover phenonemum in articulated combinations. It may be reasonable to believe that science in general is returning to a position of total ignorance and arrogance reminiscent of the Dark Ages.
Simon from SoCal,
So you think the green minded people would support an intersection that needs very wide roads taking away more and more green space? Or a road system that increases the average time? I don't see your point on emissions because the average time spent on a roundabout compared to a similarly sized traffic light intersection is far less. I don't need to cough up many facts on that, they're very easy to find. As for safety, it is safer for pedestrians and bycilists because they cross over narrow roads ways and only have to worry about traffic coming from one direction each time they touch the concrete. So the average time is less, more green space, safer for pedestrians, not wasting any energy with traffic lights and their complicated systems that go along with them, less wear and tear because you gradually stop and usually keep moving, rather than racing to beat a red light and then needing to stop completely in other times. These are local roads, not freeways. Modern Roundabouts are actually designed to handle large vehicles and they're actually designed for save and efficient traveling through our local communities. Average speed makes a lot more sense than hurry up and wait and take away all of our lane to accomodate traffic lights requiring short and multiple lines.
It would appear that it is now ten years since I wrote the article above and since then very little policy has changed at least nationally here in the UK. However, it would appear that future policy is now to be focused on reducing transport's negative effect on the environment, It is quite ironic that the Green's actually campaigned for the introduction of traffic calming, even after I sent Friends of the Earth and others letters pointing out the extra pollution it caused. There is also strong evidence to suggest that traffic calming in an area leads to an increase in asthma cases, the same is probably true for 20 Mph zones. I can only hope that concern for the environment will put an end to traffic calming once and for all. The road safety high priests will all squeal like stuck pigs but it has to be pointed out that most of them have never campaigned for annual eye-sight tests for drivers. It is estimated that 20% of drivers in the UK fail to meet the eye-sight requirements, and they are probably responsible for 50% of the serious accidents. A new roundabout was installed at a cross-roads on one of my local roads after two serious accidents in two weeks. I know for a fact that the driver involved in both as the cause was practically blind at the time of the accidents, I knew his grand-daughter well. To reduce transport's effect on Global Warming many speed limits need to be increased not cut further. When 80 Kph EU speed limiters were introduced on HGV's during the 1990s fuel consumption on local 38 tonne vehicles doing night runs fro Lancashire to Scotland increased from 9 Mpg to 7 Mpg. Higher speeds will be no problem if all drivers have decent eye-sight which is regularly tested. The only problem is will the UK government manage to wean itself off fuel tax revenues.