Low speed free-wheeling / coasting / rolling
Discussion
Just wondering what the advanced driving take on this is?
I'm specifically talking about being in in a line of traffic on a downhill slope leading to a junction of some sort.
Vehicles in the line going from being stationary, then moving forwards X car lengths, back to stationary - and this repeating until the junction is cleared.
I presume it is considered acceptable to simply release the parking brake, and modulate the brake pedal as necessary (sometimes no braking may be required)?
Depending on how far and fast traffic ahead is moving, and how close to the junction I am, I will sometimes remain in neutral (if it is apparent gravity will be sufficient), or sometimes have 2nd gear selected so that it can be engaged when required (if the gradient reduces or traffic ahead is moving more freely).
Thoughts?
I'm specifically talking about being in in a line of traffic on a downhill slope leading to a junction of some sort.
Vehicles in the line going from being stationary, then moving forwards X car lengths, back to stationary - and this repeating until the junction is cleared.
I presume it is considered acceptable to simply release the parking brake, and modulate the brake pedal as necessary (sometimes no braking may be required)?
Depending on how far and fast traffic ahead is moving, and how close to the junction I am, I will sometimes remain in neutral (if it is apparent gravity will be sufficient), or sometimes have 2nd gear selected so that it can be engaged when required (if the gradient reduces or traffic ahead is moving more freely).
Thoughts?
What's the stalling speed in 1st? In my car about 4mph. So if I am not going to get above 4mph, which in the scenario you describe, sounds likely, then rolling with the engine disengaged is reasonable if the speed is under control with the brakes (your only other option is the start to bring the clutch up through the biting point, and then disengage again, and the gains in control are infinitessimally marginal for doing so).
I would always have either 1st or 2nd selected depending on gradient with the clutch disengaged, never neutral - that gives you all possible options.
I would always have either 1st or 2nd selected depending on gradient with the clutch disengaged, never neutral - that gives you all possible options.
IME at least, it doesn't seem to have a stalling speed in 1st (assuming level or declining ground)? It will just pull itself along (it's a VAG 2.0 TDI 150ps).
I see what you are saying about always having a gear selected. The reason I have left it in neutral (at least on the particular hill I'm thinking of) is I know from previous experience of the junction that from a certain stating point traffic will be slowing and coming to a stop again, without the need for me to use any throttle to reach that point, and whilst still keeping with the flow of traffic to a reasonable degree. (ie Due the traffic light phasing).
In this scenario, 1st gear would always be unnecessary, I think, because I can see when traffic ahead is starting to move and will begin to ease off the brakes just as the car in front starts to move. Fairly often, the driver in front will appear to move off from stationary under a throttle (only to have to brake fairly firmly). I wouldn't want to replicate that, and would rather smoothly move to the next waiting point - I don't believe 1st gear would be suitable for this as I think it'd require some throttle (and then firmer braking), as without throttle I think it would hold the car back more than desired, causing a larger gap to open up to the car in front. Hence I find myself rolling off from stationary (albeit usually under very light but constant braking), and then either rolling into the next waiting position whilst still in neutral, or, rolling off and then selecting and engaging 2nd gear if traffic begins to move more freely.
It just seems peculiar to me as I get the sense that the majority of other cars in the queue are not being driven like this - most (as far as I can tell) seem to move off down hill under throttle, even though it should be pretty obvious that traffic will be stopping again. I suppose, to a degree, it maybe does come down to the characteristics of different vehicles, their engines and transmission type. Either that or perhaps the drivers just go though the 'normal' motions as if they were setting off on level ground rather than a descent.
I see what you are saying about always having a gear selected. The reason I have left it in neutral (at least on the particular hill I'm thinking of) is I know from previous experience of the junction that from a certain stating point traffic will be slowing and coming to a stop again, without the need for me to use any throttle to reach that point, and whilst still keeping with the flow of traffic to a reasonable degree. (ie Due the traffic light phasing).
In this scenario, 1st gear would always be unnecessary, I think, because I can see when traffic ahead is starting to move and will begin to ease off the brakes just as the car in front starts to move. Fairly often, the driver in front will appear to move off from stationary under a throttle (only to have to brake fairly firmly). I wouldn't want to replicate that, and would rather smoothly move to the next waiting point - I don't believe 1st gear would be suitable for this as I think it'd require some throttle (and then firmer braking), as without throttle I think it would hold the car back more than desired, causing a larger gap to open up to the car in front. Hence I find myself rolling off from stationary (albeit usually under very light but constant braking), and then either rolling into the next waiting position whilst still in neutral, or, rolling off and then selecting and engaging 2nd gear if traffic begins to move more freely.
It just seems peculiar to me as I get the sense that the majority of other cars in the queue are not being driven like this - most (as far as I can tell) seem to move off down hill under throttle, even though it should be pretty obvious that traffic will be stopping again. I suppose, to a degree, it maybe does come down to the characteristics of different vehicles, their engines and transmission type. Either that or perhaps the drivers just go though the 'normal' motions as if they were setting off on level ground rather than a descent.
MaxSo said:
IME at least, it doesn't seem to have a stalling speed in 1st (assuming level or declining ground)? It will just pull itself along (it's a VAG 2.0 TDI 150ps).
The point at which it pulls itself along... That is the stalling speed. The engine management electronics spot the stall happening and add fuel to the engine on your behalf, which pulls the car along. Same will happen in all gears (just at different speeds).MaxSo said:
It just seems peculiar to me as I get the sense that the majority of other cars in the queue are not being driven like this - most (as far as I can tell) seem to move off down hill under throttle, even though it should be pretty obvious that traffic will be stopping again. I suppose, to a degree, it maybe does come down to the characteristics of different vehicles, their engines and transmission type. Either that or perhaps the drivers just go though the 'normal' motions as if they were setting off on level ground rather than a descent.
Sounds like lack of thought and understanding on behalf of the many. Never follow the herd (unless you know alrady that the herd is correct) 
If I can see that it’s going to be a long wait before I reach the front of the queue, I will sometimes switch the engine off and roll-stop-roll-stop, using minimal movements of the brake pedal to avoid dissipating the vacuum assistance too quickly. I leave the ignition on so that the brake lights still work (although not necessary on some cars). You just need to be aware that when the vacuum runs out the brake pedal will become very hard, but at such low speeds it should never become a problem.
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