Cutting speed limits for cleaner air?
Discussion
davepoth said:
So yes, slowing the traffic down will both reduce emissions and increase capacity.
It might reduce the emissions of an individual car but if you increase capacity you'll increase emissions of the traffic.In any event the reduction in limit from 70 to 50 doesn't mean average speeds will drop 20 mph... probably just a few mph as half the traffic is already doing 55...
Gary29 said:
wc98 said:
i think the biggest problem is our "smart" roads are run by dumb people.
Are driven on by ever dumber peopleThe last time I looked at european data only Sweden had better road safety stats than the UK per billion miles travelled in a year. Poland, Latvia and Croatia all doubled the European average. Allegedly they all drive Volvos in Sweden so that result doesn't necessarily make us dumber
With a longer timescale and global reach, over the past decade (to 2016) the UK was second to Malta in the league table of "safest roads" countries in the world, according to research by the Parliamentary Advisory Council on Transport Safety. In particular, Britain had fewest vehicle occupant deaths per head of population.
Surely vehicles are at their most fuel efficient and least polluting when travelling at higher speeds, and at their least efficiency, and highest pollution production point when travelling slowly. Therefore steps should be taken to ensure vehicles are allowed to travel at their most efficient speed for as much of the time as possible.
What creates pollution is making vehicles go at slower speeds, which then requires them to use higher revs in an intermediate gear, or to be labouring along at low speed in top gear. So no, cutting speed limits will do little to achieve cleaner air and is more likely,to achieve the opposite, especially in a small overcrowded country where many roads are overcrowded for a lot of the time.
When I am travelling at speed on an open road my mpg figure goes up, when I am travelling slower in a densely packed stream of traffic it goes down, So a situation in which more vehicles are packed into a given section of road that are traveling at a less fuel efficient speed, thus producing greater levels of pollution arises.
The authorities have found that vehicles travelling at slower speeds than the posted limits such as that which occurs approaching the Dartford crossing, or crawling through cities, is often where pollution is at it highest.
What creates pollution is making vehicles go at slower speeds, which then requires them to use higher revs in an intermediate gear, or to be labouring along at low speed in top gear. So no, cutting speed limits will do little to achieve cleaner air and is more likely,to achieve the opposite, especially in a small overcrowded country where many roads are overcrowded for a lot of the time.
When I am travelling at speed on an open road my mpg figure goes up, when I am travelling slower in a densely packed stream of traffic it goes down, So a situation in which more vehicles are packed into a given section of road that are traveling at a less fuel efficient speed, thus producing greater levels of pollution arises.
The authorities have found that vehicles travelling at slower speeds than the posted limits such as that which occurs approaching the Dartford crossing, or crawling through cities, is often where pollution is at it highest.
Pan Pan Pan said:
Surely vehicles are at their most fuel efficient and least polluting when travelling at higher speeds, and at their least efficiency, and highest pollution production point when travelling slowly. Therefore steps should be taken to ensure vehicles are allowed to travel at their most efficient speed for as much of the time as possible.
What creates pollution is making vehicles go at slower speeds, which then requires them to use higher revs in an intermediate gear, or to be labouring along at low speed in top gear. So no, cutting speed limits will do little to achieve cleaner air and is more likely,to achieve the opposite, especially in a small overcrowded country where many roads are overcrowded for a lot of the time.
When I am travelling at speed on an open road my mpg figure goes up, when I am travelling slower in a densely packed stream of traffic it goes down, So a situation in which more vehicles are packed into a given section of road that are traveling at a less fuel efficient speed, thus producing greater levels of pollution arises.
The authorities have found that vehicles travelling at slower speeds than the posted limits such as that which occurs approaching the Dartford crossing, or crawling through cities, is often where pollution is at it highest.
No.What creates pollution is making vehicles go at slower speeds, which then requires them to use higher revs in an intermediate gear, or to be labouring along at low speed in top gear. So no, cutting speed limits will do little to achieve cleaner air and is more likely,to achieve the opposite, especially in a small overcrowded country where many roads are overcrowded for a lot of the time.
When I am travelling at speed on an open road my mpg figure goes up, when I am travelling slower in a densely packed stream of traffic it goes down, So a situation in which more vehicles are packed into a given section of road that are traveling at a less fuel efficient speed, thus producing greater levels of pollution arises.
The authorities have found that vehicles travelling at slower speeds than the posted limits such as that which occurs approaching the Dartford crossing, or crawling through cities, is often where pollution is at it highest.
Higher speeds means higher aerodynamic forces and friction which means higher engine load (force) which means higher fuel consumption, fact.
Lower speeds are often applied because of more traffic or irregularities in the flow of traffic (junctions, accidents etc).
It is the repeated deceleration and subsequent acceleration that increases fuel consumption at lower average speeds. Acceleration causes increased engine load in these scenarios.
Which is why 50mph speed limits intend to lower the overall average speed and reduce the variation and acceleration of motorists in high traffic environments.
No one is generally complaining about air quality at the side of motorways. It is in cities.
The best solution is to allow traffic to flow through towns and cities. Maximise greenwave schemes, switch off traffic lights when quiet, remove traffic calming. Any road feature that is designed to slow down (and then accelerate) all the traffic this is a root cause of bad pollution.
A car cruising at 80mph is running at a constant load allowing the emissions to be regulated well. A car accelerating repeatedly from 0 is certainly not hence an increase in harmful emissions.
We all really need to stop worrying about CO2 emissions it’s a complete red herring for people’s quality of life.
How much time is wasted waiting at a traffic light on an empty roundabout? It’s bizarre and government doesn’t understand how to increase productivity...!
The best solution is to allow traffic to flow through towns and cities. Maximise greenwave schemes, switch off traffic lights when quiet, remove traffic calming. Any road feature that is designed to slow down (and then accelerate) all the traffic this is a root cause of bad pollution.
A car cruising at 80mph is running at a constant load allowing the emissions to be regulated well. A car accelerating repeatedly from 0 is certainly not hence an increase in harmful emissions.
We all really need to stop worrying about CO2 emissions it’s a complete red herring for people’s quality of life.
How much time is wasted waiting at a traffic light on an empty roundabout? It’s bizarre and government doesn’t understand how to increase productivity...!
John145 said:
No one is generally complaining about air quality at the side of motorways. It is in cities.
Have you ever been through Port Talbot on the M4?Whilst it is obvious to everyone involved that the steel works has a detrimental effect on pollution, having the M4 running with metres of people's homes doesn't help either. Some literally have the motorway next to their bedroom windows.
Evanivitch said:
Pan Pan Pan said:
Surely vehicles are at their most fuel efficient and least polluting when travelling at higher speeds, and at their least efficiency, and highest pollution production point when travelling slowly. Therefore steps should be taken to ensure vehicles are allowed to travel at their most efficient speed for as much of the time as possible.
What creates pollution is making vehicles go at slower speeds, which then requires them to use higher revs in an intermediate gear, or to be labouring along at low speed in top gear. So no, cutting speed limits will do little to achieve cleaner air and is more likely,to achieve the opposite, especially in a small overcrowded country where many roads are overcrowded for a lot of the time.
When I am travelling at speed on an open road my mpg figure goes up, when I am travelling slower in a densely packed stream of traffic it goes down, So a situation in which more vehicles are packed into a given section of road that are traveling at a less fuel efficient speed, thus producing greater levels of pollution arises.
The authorities have found that vehicles travelling at slower speeds than the posted limits such as that which occurs approaching the Dartford crossing, or crawling through cities, is often where pollution is at it highest.
No.What creates pollution is making vehicles go at slower speeds, which then requires them to use higher revs in an intermediate gear, or to be labouring along at low speed in top gear. So no, cutting speed limits will do little to achieve cleaner air and is more likely,to achieve the opposite, especially in a small overcrowded country where many roads are overcrowded for a lot of the time.
When I am travelling at speed on an open road my mpg figure goes up, when I am travelling slower in a densely packed stream of traffic it goes down, So a situation in which more vehicles are packed into a given section of road that are traveling at a less fuel efficient speed, thus producing greater levels of pollution arises.
The authorities have found that vehicles travelling at slower speeds than the posted limits such as that which occurs approaching the Dartford crossing, or crawling through cities, is often where pollution is at it highest.
Higher speeds means higher aerodynamic forces and friction which means higher engine load (force) which means higher fuel consumption, fact.
Lower speeds are often applied because of more traffic or irregularities in the flow of traffic (junctions, accidents etc).
It is the repeated deceleration and subsequent acceleration that increases fuel consumption at lower average speeds. Acceleration causes increased engine load in these scenarios.
Which is why 50mph speed limits intend to lower the overall average speed and reduce the variation and acceleration of motorists in high traffic environments.
Pan Pan Pan said:
Evanivitch said:
Pan Pan Pan said:
Surely vehicles are at their most fuel efficient and least polluting when travelling at higher speeds, and at their least efficiency, and highest pollution production point when travelling slowly. Therefore steps should be taken to ensure vehicles are allowed to travel at their most efficient speed for as much of the time as possible.
What creates pollution is making vehicles go at slower speeds, which then requires them to use higher revs in an intermediate gear, or to be labouring along at low speed in top gear. So no, cutting speed limits will do little to achieve cleaner air and is more likely,to achieve the opposite, especially in a small overcrowded country where many roads are overcrowded for a lot of the time.
When I am travelling at speed on an open road my mpg figure goes up, when I am travelling slower in a densely packed stream of traffic it goes down, So a situation in which more vehicles are packed into a given section of road that are traveling at a less fuel efficient speed, thus producing greater levels of pollution arises.
The authorities have found that vehicles travelling at slower speeds than the posted limits such as that which occurs approaching the Dartford crossing, or crawling through cities, is often where pollution is at it highest.
No.What creates pollution is making vehicles go at slower speeds, which then requires them to use higher revs in an intermediate gear, or to be labouring along at low speed in top gear. So no, cutting speed limits will do little to achieve cleaner air and is more likely,to achieve the opposite, especially in a small overcrowded country where many roads are overcrowded for a lot of the time.
When I am travelling at speed on an open road my mpg figure goes up, when I am travelling slower in a densely packed stream of traffic it goes down, So a situation in which more vehicles are packed into a given section of road that are traveling at a less fuel efficient speed, thus producing greater levels of pollution arises.
The authorities have found that vehicles travelling at slower speeds than the posted limits such as that which occurs approaching the Dartford crossing, or crawling through cities, is often where pollution is at it highest.
Higher speeds means higher aerodynamic forces and friction which means higher engine load (force) which means higher fuel consumption, fact.
Lower speeds are often applied because of more traffic or irregularities in the flow of traffic (junctions, accidents etc).
It is the repeated deceleration and subsequent acceleration that increases fuel consumption at lower average speeds. Acceleration causes increased engine load in these scenarios.
Which is why 50mph speed limits intend to lower the overall average speed and reduce the variation and acceleration of motorists in high traffic environments.
So if I travelled 100 miles, would I use more fuel if I took one hour or two?
You should drive at the highest gear possible, and here's the important bit, for the speed that you are doing. That's to minimise thermodynamic losses within the vehicle. It doesn't negate aerodynamic forces.
Why do so many idiots think that driving at low revs in the highest gear is more efficient than a lower speed in a appropriate gear!? Engines can't defy the laws of thermodynamics or aerodynamics. The faster you go the more work the engine must do to overcome the forces working against it. Changing to a higher gear doesn't change that.
Evanivitch said:
Pan Pan Pan said:
Evanivitch said:
Pan Pan Pan said:
Surely vehicles are at their most fuel efficient and least polluting when travelling at higher speeds, and at their least efficiency, and highest pollution production point when travelling slowly. Therefore steps should be taken to ensure vehicles are allowed to travel at their most efficient speed for as much of the time as possible.
What creates pollution is making vehicles go at slower speeds, which then requires them to use higher revs in an intermediate gear, or to be labouring along at low speed in top gear. So no, cutting speed limits will do little to achieve cleaner air and is more likely,to achieve the opposite, especially in a small overcrowded country where many roads are overcrowded for a lot of the time.
When I am travelling at speed on an open road my mpg figure goes up, when I am travelling slower in a densely packed stream of traffic it goes down, So a situation in which more vehicles are packed into a given section of road that are traveling at a less fuel efficient speed, thus producing greater levels of pollution arises.
The authorities have found that vehicles travelling at slower speeds than the posted limits such as that which occurs approaching the Dartford crossing, or crawling through cities, is often where pollution is at it highest.
No.What creates pollution is making vehicles go at slower speeds, which then requires them to use higher revs in an intermediate gear, or to be labouring along at low speed in top gear. So no, cutting speed limits will do little to achieve cleaner air and is more likely,to achieve the opposite, especially in a small overcrowded country where many roads are overcrowded for a lot of the time.
When I am travelling at speed on an open road my mpg figure goes up, when I am travelling slower in a densely packed stream of traffic it goes down, So a situation in which more vehicles are packed into a given section of road that are traveling at a less fuel efficient speed, thus producing greater levels of pollution arises.
The authorities have found that vehicles travelling at slower speeds than the posted limits such as that which occurs approaching the Dartford crossing, or crawling through cities, is often where pollution is at it highest.
Higher speeds means higher aerodynamic forces and friction which means higher engine load (force) which means higher fuel consumption, fact.
Lower speeds are often applied because of more traffic or irregularities in the flow of traffic (junctions, accidents etc).
It is the repeated deceleration and subsequent acceleration that increases fuel consumption at lower average speeds. Acceleration causes increased engine load in these scenarios.
Which is why 50mph speed limits intend to lower the overall average speed and reduce the variation and acceleration of motorists in high traffic environments.
So if I travelled 100 miles, would I use more fuel if I took one hour or two?
You should drive at the highest gear possible, and here's the important bit, for the speed that you are doing. That's to minimise thermodynamic losses within the vehicle. It doesn't negate aerodynamic forces.
Why do so many idiots think that driving at low revs in the highest gear is more efficient!? Engines can't defy the laws of thermodynamics or aerodynamics. The faster you go the more work the engine must do to overcome the forces working against it. Changing to a higher gear doesn't change that.
Are you serious?. Most modern cars have very low drag coefficients, and every vehicle has an optimum speed at which it can travel, covering the most distance at its optimum speed.
50 mph is not, let me repeat that, not an optimum speed for most of the vehicles on UK roads, especially for those who must cover long distances, Artificially limiting speed to 50mph is not going to change emissions from UK vehicles very much from a vehicle doing 70 mph.
For a given journey artificially limiting a vehicles speed below its optimum speed means it will have to run for another half hour to cover the same distance If you were talking about speed well above a vehicles optimum speed, you might have a point, but that is not what is being discussed.
This suggested 50 mph limit is just another snide attempt by some, to make the whole point of car use less desirable or useful to the majority of road users, and would do virtually nothing if anything to change emissions from cars, Only a drastic reduction in the number of cars on UK roads would do that, but perhaps that is what you want to happen, are you anti car?
Pan Pan Pan said:
Evanivitch said:
Pan Pan Pan said:
Evanivitch said:
Pan Pan Pan said:
Surely vehicles are at their most fuel efficient and least polluting when travelling at higher speeds, and at their least efficiency, and highest pollution production point when travelling slowly. Therefore steps should be taken to ensure vehicles are allowed to travel at their most efficient speed for as much of the time as possible.
What creates pollution is making vehicles go at slower speeds, which then requires them to use higher revs in an intermediate gear, or to be labouring along at low speed in top gear. So no, cutting speed limits will do little to achieve cleaner air and is more likely,to achieve the opposite, especially in a small overcrowded country where many roads are overcrowded for a lot of the time.
When I am travelling at speed on an open road my mpg figure goes up, when I am travelling slower in a densely packed stream of traffic it goes down, So a situation in which more vehicles are packed into a given section of road that are traveling at a less fuel efficient speed, thus producing greater levels of pollution arises.
The authorities have found that vehicles travelling at slower speeds than the posted limits such as that which occurs approaching the Dartford crossing, or crawling through cities, is often where pollution is at it highest.
No.What creates pollution is making vehicles go at slower speeds, which then requires them to use higher revs in an intermediate gear, or to be labouring along at low speed in top gear. So no, cutting speed limits will do little to achieve cleaner air and is more likely,to achieve the opposite, especially in a small overcrowded country where many roads are overcrowded for a lot of the time.
When I am travelling at speed on an open road my mpg figure goes up, when I am travelling slower in a densely packed stream of traffic it goes down, So a situation in which more vehicles are packed into a given section of road that are traveling at a less fuel efficient speed, thus producing greater levels of pollution arises.
The authorities have found that vehicles travelling at slower speeds than the posted limits such as that which occurs approaching the Dartford crossing, or crawling through cities, is often where pollution is at it highest.
Higher speeds means higher aerodynamic forces and friction which means higher engine load (force) which means higher fuel consumption, fact.
Lower speeds are often applied because of more traffic or irregularities in the flow of traffic (junctions, accidents etc).
It is the repeated deceleration and subsequent acceleration that increases fuel consumption at lower average speeds. Acceleration causes increased engine load in these scenarios.
Which is why 50mph speed limits intend to lower the overall average speed and reduce the variation and acceleration of motorists in high traffic environments.
So if I travelled 100 miles, would I use more fuel if I took one hour or two?
You should drive at the highest gear possible, and here's the important bit, for the speed that you are doing. That's to minimise thermodynamic losses within the vehicle. It doesn't negate aerodynamic forces.
Why do so many idiots think that driving at low revs in the highest gear is more efficient!? Engines can't defy the laws of thermodynamics or aerodynamics. The faster you go the more work the engine must do to overcome the forces working against it. Changing to a higher gear doesn't change that.
Are you serious?. Most modern cars have very low drag coefficients, and every vehicle has an optimum speed at which it can travel, covering the most distance at its optimum speed.
50 mph is not, let me repeat that, not an optimum speed for most of the vehicles on UK roads, especially for those who must cover long distances, Artificially limiting speed to 50mph is not going to change emissions from UK vehicles very much from a vehicle doing 70 mph.
For a given journey artificially limiting a vehicles speed below its optimum speed means it will have to run for another half hour to cover the same distance If you were talking about speed well above a vehicles optimum speed, you might have a point, but that is not what is being discussed.
This suggested 50 mph limit is just another snide attempt by some, to make the whole point of car use less desirable or useful to the majority of road users, and would do virtually nothing if anything to change emissions from cars, Only a drastic reduction in the number of cars on UK roads would do that, but perhaps that is what you want to happen, are you anti car?
Pan Pan Pan said:
Are you serious?. Most modern cars have very low drag coefficients, and every vehicle has an optimum speed at which it can travel, covering the most distance at its optimum speed.
50 mph is not, let me repeat that, not an optimum speed for most of the vehicles on UK roads, especially for those who must cover long distances, Artificially limiting speed to 50mph is not going to change emissions from UK vehicles very much from a vehicle doing 70 mph.
For a given journey artificially limiting a vehicles speed below its optimum speed means it will have to run for another half hour to cover the same distance If you were talking about speed well above a vehicles optimum speed, you might have a point, but that is not what is being discussed.
This suggested 50 mph limit is just another snide attempt by some, to make the whole point of car use less desirable or useful to the majority of road users, and would do virtually nothing if anything to change emissions from cars, Only a drastic reduction in the number of cars on UK roads would do that, but perhaps that is what you want to happen, are you anti car?
At what point does the aerodynamic resistance and friction on a car decrease at a greater speed?50 mph is not, let me repeat that, not an optimum speed for most of the vehicles on UK roads, especially for those who must cover long distances, Artificially limiting speed to 50mph is not going to change emissions from UK vehicles very much from a vehicle doing 70 mph.
For a given journey artificially limiting a vehicles speed below its optimum speed means it will have to run for another half hour to cover the same distance If you were talking about speed well above a vehicles optimum speed, you might have a point, but that is not what is being discussed.
This suggested 50 mph limit is just another snide attempt by some, to make the whole point of car use less desirable or useful to the majority of road users, and would do virtually nothing if anything to change emissions from cars, Only a drastic reduction in the number of cars on UK roads would do that, but perhaps that is what you want to happen, are you anti car?
So say 50mph was the optimum speed for a car. Over 100 miles, would it use more or less fuel than travelling at 25mph? Broad terms, no need to reach into BSFC.
Evanivitch said:
Are you serious?
So if I travelled 100 miles, would I use more fuel if I took one hour or two?
You should drive at the highest gear possible, and here's the important bit, for the speed that you are doing. That's to minimise thermodynamic losses within the vehicle. It doesn't negate aerodynamic forces.
Why do so many idiots think that driving at low revs in the highest gear is more efficient than a lower speed in a appropriate gear!? Engines can't defy the laws of thermodynamics or aerodynamics. The faster you go the more work the engine must do to overcome the forces working against it. Changing to a higher gear doesn't change that.
Effeciency and economy aren't the same thing though. I was under the impression that engines convert fuel to useful work best at peak torque. Look at the damage pottering about is doing to diesel engines So if I travelled 100 miles, would I use more fuel if I took one hour or two?
You should drive at the highest gear possible, and here's the important bit, for the speed that you are doing. That's to minimise thermodynamic losses within the vehicle. It doesn't negate aerodynamic forces.
Why do so many idiots think that driving at low revs in the highest gear is more efficient than a lower speed in a appropriate gear!? Engines can't defy the laws of thermodynamics or aerodynamics. The faster you go the more work the engine must do to overcome the forces working against it. Changing to a higher gear doesn't change that.
Willy Nilly said:
Effeciency and economy aren't the same thing though.
Semantics. Both the ratio of fuel used to useful work.That may be power, it may be distance travelled.
Willy Nilly said:
I was under the impression that engines convert fuel to useful work best at peak torque. Look at the damage pottering about is doing to diesel engines
Which is why we have gearboxes, to keep engines at their optimum rev position for what we desire.I’d agree max fuel efficiency would be at max torque, and that the faster you go the more you pollute.
What really knackers air quality is changes in speed.
20-30, then back down to 20 really doesn’t help, neither do dumb computer controlled motorways with constantly varying speed limits.
Speed humps, merge in turn, traffic lights, and the greatest green fallacy that I see on the roads - the cyclist - get one of those wobbling along the gutter of a busy single carriageway, add in the new six feet away to avoid six feet under rule, and you’ll see emergency braking, excessive acceleration, and everything else guaranteed to kick out a load of extra fumes. I’d love to see a study on how much co2 the average two wheeled commuter is responsible for.
Make cars operate smoother, get them to cruise at steady speeds, and air quality will improve.
Try and tell that to the road planners though...
What really knackers air quality is changes in speed.
20-30, then back down to 20 really doesn’t help, neither do dumb computer controlled motorways with constantly varying speed limits.
Speed humps, merge in turn, traffic lights, and the greatest green fallacy that I see on the roads - the cyclist - get one of those wobbling along the gutter of a busy single carriageway, add in the new six feet away to avoid six feet under rule, and you’ll see emergency braking, excessive acceleration, and everything else guaranteed to kick out a load of extra fumes. I’d love to see a study on how much co2 the average two wheeled commuter is responsible for.
Make cars operate smoother, get them to cruise at steady speeds, and air quality will improve.
Try and tell that to the road planners though...
andy43 said:
I’d agree max fuel efficiency would be at max torque, and that the faster you go the more you pollute.
What really knackers air quality is changes in speed.
20-30, then back down to 20 really doesn’t help, neither do dumb computer controlled motorways with constantly varying speed limits.
Speed humps, merge in turn, traffic lights, and the greatest green fallacy that I see on the roads - the cyclist - get one of those wobbling along the gutter of a busy single carriageway, add in the new six feet away to avoid six feet under rule, and you’ll see emergency braking, excessive acceleration, and everything else guaranteed to kick out a load of extra fumes. I’d love to see a study on how much co2 the average two wheeled commuter is responsible for.
Make cars operate smoother, get them to cruise at steady speeds, and air quality will improve.
Try and tell that to the road planners though...
And yet some want to limit the speed of vehicles to 50mph on the only sections of road where they can operate at their optimum speed, for the dubious advantage of achieving a slight if any reduction in emissions. What really knackers air quality is changes in speed.
20-30, then back down to 20 really doesn’t help, neither do dumb computer controlled motorways with constantly varying speed limits.
Speed humps, merge in turn, traffic lights, and the greatest green fallacy that I see on the roads - the cyclist - get one of those wobbling along the gutter of a busy single carriageway, add in the new six feet away to avoid six feet under rule, and you’ll see emergency braking, excessive acceleration, and everything else guaranteed to kick out a load of extra fumes. I’d love to see a study on how much co2 the average two wheeled commuter is responsible for.
Make cars operate smoother, get them to cruise at steady speeds, and air quality will improve.
Try and tell that to the road planners though...
We already have 20/30/40 mph limits in built up areas where drivers are required to drive at higher RPM in the lower gears, or labour the engine at low speeds in the higher gears. we certainly do not need a 50mphlimit on motorways. The 50mph limit was probably thought of by people who don't have to drive far, if at all, who don't realize what an impediment to progress and business that a low speed limit on a long distance journey will be.
Pan Pan Pan said:
andy43 said:
I’d agree max fuel efficiency would be at max torque, and that the faster you go the more you pollute.
What really knackers air quality is changes in speed.
20-30, then back down to 20 really doesn’t help, neither do dumb computer controlled motorways with constantly varying speed limits.
Speed humps, merge in turn, traffic lights, and the greatest green fallacy that I see on the roads - the cyclist - get one of those wobbling along the gutter of a busy single carriageway, add in the new six feet away to avoid six feet under rule, and you’ll see emergency braking, excessive acceleration, and everything else guaranteed to kick out a load of extra fumes. I’d love to see a study on how much co2 the average two wheeled commuter is responsible for.
Make cars operate smoother, get them to cruise at steady speeds, and air quality will improve.
Try and tell that to the road planners though...
And yet some want to limit the speed of vehicles to 50mph on the only sections of road where they can operate at their optimum speed, for the dubious advantage of achieving a slight if any reduction in emissions. What really knackers air quality is changes in speed.
20-30, then back down to 20 really doesn’t help, neither do dumb computer controlled motorways with constantly varying speed limits.
Speed humps, merge in turn, traffic lights, and the greatest green fallacy that I see on the roads - the cyclist - get one of those wobbling along the gutter of a busy single carriageway, add in the new six feet away to avoid six feet under rule, and you’ll see emergency braking, excessive acceleration, and everything else guaranteed to kick out a load of extra fumes. I’d love to see a study on how much co2 the average two wheeled commuter is responsible for.
Make cars operate smoother, get them to cruise at steady speeds, and air quality will improve.
Try and tell that to the road planners though...
We already have 20/30/40 mph limits in built up areas where drivers are required to drive at higher RPM in the lower gears, or labour the engine at low speeds in the higher gears. we certainly do not need a 50mphlimit on motorways. The 50mph limit was probably thought of by people who don't have to drive far, if at all, who don't realize what an impediment to progress and business that a low speed limit on a long distance journey will be.
Pan Pan Pan said:
And yet some want to limit the speed of vehicles to 50mph on the only sections of road where they can operate at their optimum speed, for the dubious advantage of achieving a slight if any reduction in emissions.
You keep making these vague statements, where are your facts? What is optimum speed?,Evanivitch said:
Pan Pan Pan said:
And yet some want to limit the speed of vehicles to 50mph on the only sections of road where they can operate at their optimum speed, for the dubious advantage of achieving a slight if any reduction in emissions.
You keep making these vague statements, where are your facts? What is optimum speed?,Gassing Station | News, Politics & Economics | Top of Page | What's New | My Stuff