A theory, do Auto boxes cause traffic jams?

[humpbackmaniac]

Now we enthusiasts only really brake when required but with a high percentage of modern cars being Auto, and hence have very little engine braking drivers are required to brush the brake pedal to scrub off even the slightest amount of speed.
In so doing cause the driver behind to brake, he's just seen the tailights come on so does so by reaction, having a knock on effect which causes a jam further back as the level of braking escalates down the chain.

Any strength to that theory?

[rottie102]

I think manual boxes being responsible for people stalling at the traffic lights have equal effect

[mikey77]

Just because you see a flicker of brake lights ahead of you it doesn't mean you immediately have to jump on your own brakes.

[RizzoTheRat]

A lot of modern manuals have bugger all engine braking either. For anyone that knows the A303 I can come over the top of the hill before Solstice services at 70 and be pushing 80 at the bottom without touching the throttle, not what I expected from a 2 litre diesel. Presumably done for fuel economy as it uses no fuel down the hill.

[Codswallop]

humpbackmaniac said:

Now we enthusiasts only really brake when required but with a high percentage of modern cars being Auto, and hence have very little engine braking drivers are required to brush the brake pedal to scrub off even the slightest amount of speed.
In so doing cause the driver behind to brake, he's just seen the tailights come on so does so by reaction, having a knock on effect which causes a jam further back as the level of braking escalates down the chain.

Any strength to that theory?

Wouldn't be a problem if other drivers left a safe gap and actually paid attention to the task of driving. Therefore, traffic jams are caused by inattentive muppets who don't leave enough space, don't pay attention, or who cannot effectively modulate the brake pedal.

[jagnet]

mikey77 said:

Just because you see a flicker of brake lights ahead of you it doesn't mean you immediately have to jump on your own brakes.

Though I suspect for the majority of those travelling nose to tail at 85mph in the outside lane irrespective of weather conditions it does. Those trains scare the hell out of me, and I often find myself retreating to lane one until they pass.

No reason you can't use engine braking in an auto if you want, but how many actually do?

[blearyeyedboy]

jagnet said:

Though I suspect for the majority of those travelling nose to tail at 85mph in the outside lane irrespective of weather conditions it does. Those trains scare the hell out of me, and I often find myself retreating to lane one until they pass.

No reason you can't use engine braking in an auto if you want, but how many actually do?

You can do, but let's be honest, it's harder to do it smoothly and effectively in all but the most compliant autos.

And I entirely agree about these nose-to-tail trains. They're terrifying. Glad it's not just me who moves out of their way.

[300bhp/ton]

humpbackmaniac said:

Now we enthusiasts only really brake when required but with a high percentage of modern cars being Auto, and hence have very little engine braking drivers are required to brush the brake pedal to scrub off even the slightest amount of speed.
In so doing cause the driver behind to brake, he's just seen the tailights come on so does so by reaction, having a knock on effect which causes a jam further back as the level of braking escalates down the chain.

Any strength to that theory?

None what so ever. It's more to do with too many impatient people in the fast lane driving to close to the car in front at high speed.

[blearyeyedboy]

While I think of it, don't the IAM advise you tap your brake pedal to alert any slightly dozy drivers behind you to the fact you're slowing down? In which case, automatic transmission is a moot point.

[Disco You]

mikey77 said:

Just because you see a flicker of brake lights ahead of you it doesn't mean you immediately have to jump on your own brakes.

This. People who can't drive cause traffic jams.

[John D.]

I don't feel the need to use the brakes to scrub off speed in my auto any more than I do in a manual. It is a three litre straight six though

I can see where the OP is coming from but to me it is more a case of anticipation (or lack of!). By reading the traffic ahead it is often easy to know when to ease off so that you need not apply the brakes to avoid getting too close to the car ahead.

I have noticed Mercedes drivers do often seem to be the one of the more common 'brake dabbers' on the motorway, so maybe there is something in the auto theory.

[kambites]

If anything, I'd say autos are better in this regard because firstly you can't really engine brake heavily (so the car behind will notice sooner than you're slowing down, and hence not brake excessively to avoid you) and secondly it's easier to creep - for traffic to go from moving to completely stopped, someone has to stop when the car in front of them didn't.

[rottie102]

John D. said:

I don't feel the need to use the brakes to scrub off speed in my auto any more than I do in a manual. It is a three litre straight six though

What does that mean?

[thinfourth2]

I have this thing called a window

I don't know if it is fitted to modern cars

But it lets you see what is happening further up the road

If it is fitted to modern cars they must be crap as it appears the drivers can only see 5 foot in front of the bonnet

[Leptons]

RizzoTheRat said:

A I can come over the top of the hill before Solstice services at 70 and be pushing 80 at the bottom without touching the throttle, not what I expected from a 2 litre diesel.

Thats exactly what I would expect. Diesels have very little, if any engine breaking.

[chris7676]

No.

(Btw, it's a bit nuts to drive like an enthusiast in heavy traffic)

[alfa pint]

Codswallop said:

humpbackmaniac said:

Now we enthusiasts only really brake when required but with a high percentage of modern cars being Auto, and hence have very little engine braking drivers are required to brush the brake pedal to scrub off even the slightest amount of speed.
In so doing cause the driver behind to brake, he's just seen the tailights come on so does so by reaction, having a knock on effect which causes a jam further back as the level of braking escalates down the chain.

Any strength to that theory?

Wouldn't be a problem if other drivers left a safe gap and actually paid attention to the task of driving. Therefore, traffic jams are caused by inattentive muppets who don't leave enough space, don't pay attention, or who cannot effectively modulate the brake pedal.

^^^ This. If people left such a thing as a braking distance, they would see the gap shrinking and take the foot off the gas. Since they don't leave a braking distance, they have to slam the anchors on, causing the caterpillar shuffle affect back up the line of cars.

[175gt]

I think many modern auto' boxes now hold gears under certain circumstances and do provide a degree of engine braking.

And (correct me if I'm wrong), whilst gearing might have an influence, surely a diesel engine is much harder to turn over and is far better than a petrol for providing engine braking?

[John D.]

rottie102 said:

John D. said:

I don't feel the need to use the brakes to scrub off speed in my auto any more than I do in a manual. It is a three litre straight six though

What does that mean?

What does what mean?

Scrub off speed? - Slow slightly by a few mph.

The reason I gave the engine size? - Larger engines generally have more engine braking.

So cruising in traffic around town or on the motorway I do not find myself using the brakes to scrub off speed any more in my auto than any manual I've driven.

[blearyeyedboy]

John D. said:

I don't feel the need to use the brakes to scrub off speed in my auto any more than I do in a manual. It is a three litre straight six though

Shhh, I'm already trying to resist getting into more debt by buying a car with an inline six to replace my four-pot turbo. I don't need any more excuses!

So keep providing them please!