Eco driving causes jams

So-called economical driving techniques are counter-productive because they worsen congestion, thereby generating extra pollution, claims Nigel Humphries, spokesman for the Association of British Drivers.

There is considerable advice floating around on how to drive economically, but much of this can cause congestion for others and so increase overall fuel consumption. Some tips are downright wrong and others are even dangerous.

All road users have a duty to facilitate the smooth flow of traffic and minimize congestion at every opportunity. This is the true way to minimize overall fuel usage. Unfortunately most current advice is of a selfish nature, advising drivers how to cut their own consumption with no regard to the effects on other road users and traffic flow.

Examples of congestion causing behaviour resulting from “crawl everywhere” eco advice include:

• Travelling below the 56mph limited speed of HGVs on motorways, forcing trucks to slow down and then accelerate back up to speed, or to change lanes to overtake
• Joining motorways from slip roads at speeds below that of the traffic already on the road, creating braking and lane changes
• Slowing down to leave the motorway before entering the slip road to avoid braking at the end of it
• Holding up traffic on single carriageway roads causing unnecessary overtaking
• Crawling away from traffic lights and so reducing the number of vehicles that can get through on green
• Turning the engine off whilst at a red light and then being slow to restart it.

Efficient driving to cut congestion can cut journey times for all, save fuel for all and help the British economy. The AA estimates that congestion costs our economy £20bn a year.

Congestion causes consumption

The ABD is calling for public advice campaigns to switch their focus and look at the overall picture. Congestion is the biggest waster of fuel and biggest cause of pollution. Slow moving, stop/start traffic is the least fuel efficient. Whilst the authorities seem to do all that they can to increase congestion there is much individual road users can do to prevent it.

The following advice from the ABD is designed to minimise congestion and thereby increase fuel efficiency.

At traffic lights, the vital thing is to maximise the number of vehicles getting through each green phase. Don’t dither! Drivers should predict when lights are going to change to green and be ready in gear to go immediately if safe to proceed. The first driver should accelerate briskly, following drivers should move as soon as he goes and keep up. Whilst of course they must maintain a safe distance, this should not be excessive. When approaching green lights proceed at a speed where you can safely stop if they change or other hazards appear but there is no need to slow more. Try to anticipate light changes to avoid stopping if possible. Don’t straddle lanes and indicate your intentions clearly for the benefit of drivers and pedestrians.

Drivers should also avoid blocking junctions. When turning right position your vehicle close to the centre line so others can filter to your left. When exiting T junctions form two lanes as soon as there is space. Don’t dither and be ready to go.

Roundabout navigation

At roundabouts drivers should form two or more lanes on approach at the earliest opportunity. Don’t stop or slow more than is necessary if your path onto the roundabout is clear.

Maintain your lane through the roundabout allowing others to proceed in their lanes alongside you. Lanes are not usually marked on roundabouts but still need to be observed for efficient use.

Don’t ‘straightline’ roundabouts or cut across where other traffic is present.

Indicate your intentions where appropriate. For example if you indicate left when taking an exit this allows others to confidently enter from that exit and enables pedestrians to make decisions when to cross safely.

When entering motorways, drivers should accelerate on the slip road and merge smoothly at the speed of traffic in lane one. Don’t disrupt or impede flow by entering too slowly.

When exiting leave the motorway at the general speed of lane one then slow down once on the slip road. Try not to slow down or brake whilst still in lane one as this can cause great disruption to flow (there are exceptions where slip roads are short or congested).

It can be more efficient to keep a constant throttle opening and gain speed on downhill stretches, allowing speed to drop off uphill, but don’t obstruct other traffic while you are doing this (and watch your speed!).

Don’t hog the outer lanes. If not overtaking other traffic move to the left. Staying in the middle or outer lane when lane one is clear seriously impedes the flow of traffic and is an inefficient use of roadspace.

Avoid braking on the motorway unless unavoidable. Your brake lights will cause a chain reaction, which is exaggerated as it filters back. Try to drive at an even speed. If you see stationary traffic ahead, try to slow down early in the hope it will be moving again by the time you arrive!

Remember, trucks are electronically governed to 56mph (90km/h). Do not impede their progress by driving slower than this as it means they have to change lane to pass you. Remember also that trucks and caravans cannot use the outer lane.

Traffic bunching

The most efficient traffic is smooth free flowing traffic. When driving on single carriageway roads ensure you are driving at a speed where you are not holding others up. If you need to drive slower than the natural pace of traffic for the road then pull in at every safe opportunity to let any build up of traffic behind you pass. Keep an eye in the mirror. If a number of cars are bunched up behind you then you are likely causing a hazard and should consider pulling over or increasing your speed.

Don’t sit close behind other slow moving traffic if not intending to overtake. You are creating a double hazard for others to overtake. Don’t slow down more than is necessary for bends.

The secret of safe driving is to always drive at a speed at which you can safely stop in the distance you can guarantee to be clear. There is no need to slow more than this for bends, it wastes the fuel of all behind you who are forced to brake and accelerate too.

Cyclists can play a part too by indicating their intentions. Those who don’t often leave other road users, such as drivers, pedestrians and other cyclists sitting at junctions for long periods only to watch the cyclist turn off.

Finally ABD’s advice for pedestrians is, if you are not going to wait for the ‘green man’ on signalised crossings, then don’t press the button. This brings traffic to a standstill pointlessly after you have crossed.
 

The blog quotes the AA as estimating the annual cost of congestion for the UK as £20 billion (US$29.7 billion). However, there are many ways to skin a cat and other researchers say the cost is far less, at £6.9 billion (US$10.2 billion) per annum (Dodgson & Lane)  and £2.1 billion (US$3.1 billion) per quarter (Trafficmaster). It's such an inexact science that nobody has dared to put a figure on it for a decade. Even the CBI has stopped promoting its own estimates.

A more intersting figure comes from the Eddington report which says that road pricing could generate benefits to the UK worth £28 billion (US$41.5 billion) a year in 2025