Second thoughts on offsiding

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Astraist
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Second thoughts on offsiding

Postby Astraist » Mon Aug 06, 2018 9:57 pm

'm back.

Anyway, I've been having second thoughts about the concept of offsiding. Which isn't a huge deal since I rarely use it: its not a widely-known concept in the Israeli Advanced Driving coaching community. I only use it when no other road user is in sight, for fear that it would be percieved incorrectly and unfavorably.

I mostly deal with defensive driving in traffic. When it comes to the bendy sections of the road, my philosophy is to drive in a such a way as to use the least of the car's performance envelope and retain as much of it readily for unforseen emergencies. But which?

I don't consider excessive speed (be it through judgment of entry speed or corner radius) to be such an emergency. If a driver understands the concept of offsiding and uses it intentionally, his or her observational skills are probably too good to misjudge a corner too severly. Offsiding requires a very good view, which tends to correlate with corner radii that aren't that severe anyway.

Rather, the two causes I always have in mind are: a) a need for further action mid-corner due to another driver's misconduct or b) an unforseen decrease in road grip mid-corner.

As with excessive speed, the former is wholly irrelevant to any case in which offsiding is purposefully deployed. Like I said, I do it when no other road users are in sight, so naturally none would be there to use more than their fair share of the road.

The latter is of course still in effect but here's the thing: say there's a large spill of oil that is masked by the lighting conditions or a clear patch of ice. If we offside, we increase the radius dramatically, such that if we hit it, it'd be for a much smaller lateral force and therefore a loss of car control would be less likely. However, by using twice as much of the road, we're increasing the chance to meet such a slippery patch, should it only occur on one side of the roadway - which is not an unlikely concept given superelevation of corners or (in driving abroad) that of freezing rain. Slippery agents often pool in the area of transition from road-crown to superelevation which, if one is offsiding, one would be traversing with the car turning.

So, should we offside at all?

kfae8959
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Re: Second thoughts on offsiding

Postby kfae8959 » Mon Aug 06, 2018 10:50 pm

Yes.

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jont-
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Re: Second thoughts on offsiding

Postby jont- » Tue Aug 07, 2018 5:51 am

Astraist wrote:'However, by using twice as much of the road,

Is your car suddenly twice as wide?

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Horse
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Re: Second thoughts on offsiding

Postby Horse » Tue Aug 07, 2018 6:28 am

jont- wrote:
Astraist wrote:'However, by using twice as much of the road,

Is your car suddenly twice as wide?


Using both sides of the road, albeit probably only one at a time ;)

OFFside & NEARside, 1 + 1 = 2 (except, as a mate says, for high values of '1')
My own views. For better or worse :)

ancient
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Re: Second thoughts on offsiding

Postby ancient » Tue Aug 07, 2018 8:07 am

Horse wrote:
jont- wrote:
Astraist wrote:'However, by using twice as much of the road,

Is your car suddenly twice as wide?


Using both sides of the road, albeit probably only one at a time ;)

OFFside & NEARside, 1 + 1 = 2 (except, as a mate says, for high values of '1')

But only using one at a time. If the hypothetical oil/ice patch is on only one side of the road, the chances of it being on the near side presumably equal those of it being on the off side (exempt conditions where one side experiences more weather than the other - and then you choose the obviously-safer side; but this scenario dictates that the patch is invisible, from which I assume it is also unpredictable). Given the equal chances, neither side of the road is more likely to be less (or more) slippery than the other and there is not any increased chance of hitting the hypothetical patch by off-siding. So the choice should be to apply less sideways force on the car: Hence yes we should be off-siding.

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akirk
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Re: Second thoughts on offsiding

Postby akirk » Tue Aug 07, 2018 8:16 am

for me, offsiding has one of two purposes:
- opening up vision
- straightening the path

opening up vision might be a way of just checking the extra bits on a bend through which I can see, or it might be to gain earlier vision around the bend, either way, I would come back in early enough that the space I can see ahead still gives me the safety contingency I want - so if the bend proves to be closing down I would come back in earlier - job done, I will gain nothing more, just add risk... but if it is opening up, it might give enough additional vision to stay out - all depends on the bend...

straightening the path assumes either already having the vision / or gaining sufficient vision, and is about stability - as long as the road is clear I see this as no greater risk of debris or oil spills etc. - the stats on increased space being used don't work as the car takes up a car's space where-ever it is - adding road to use, also subtracts road used elsewhere...

Alasdair

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Horse
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Re: Second thoughts on offsiding

Postby Horse » Tue Aug 07, 2018 8:39 am

ancient wrote:
Horse wrote:
jont- wrote:
Astraist wrote:'However, by using twice as much of the road,

Is your car suddenly twice as wide?


Using both sides of the road, albeit probably only one at a time ;)

OFFside & NEARside, 1 + 1 = 2 (except, as a mate says, for high values of '1')

But only using one at a time. If the hypothetical oil/ice patch is on only one side of the road, the chances of it being on the near side presumably equal those of it being on the off side (exempt conditions where one side experiences more weather than the other - and then you choose the obviously-safer side; but this scenario dictates that the patch is invisible, from which I assume it is also unpredictable). Given the equal chances, neither side of the road is more likely to be less (or more) slippery than the other and there is not any increased chance of hitting the hypothetical patch by off-siding. So the choice should be to apply less sideways force on the car: Hence yes we should be off-siding.


You may not have noticed the ' ;) ' applied mid-post? Ah well, never mind.

As far as spilt diesel, from over-flowing tanks, the location of that can sometimes be predicted as it will tend to be flung 'out'. But I wouldn't claim it as an exact science ;) [oh look, another one]
My own views. For better or worse :)

Astraist
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Re: Second thoughts on offsiding

Postby Astraist » Tue Aug 07, 2018 9:49 am

ancient wrote:But only using one at a time. If the hypothetical oil/ice patch is on only one side of the road, the chances of it being on the near side presumably equal those of it being on the off side (exempt conditions where one side experiences more weather than the other - and then you choose the obviously-safer side; but this scenario dictates that the patch is invisible, from which I assume it is also unpredictable). Given the equal chances, neither side of the road is more likely to be less (or more) slippery than the other and there is not any increased chance of hitting the hypothetical patch by off-siding. So the choice should be to apply less sideways force on the car: Hence yes we should be off-siding.


Yes, I'm assuming the lighting conditions are such that the slippery section of road is not visible. Otherwise, its not unreasonable to assume that if its too small to be noticed - its probably not going to affect the car's handling too adversly.

As for it being equally likely on either part of the bend - I don't know. There are a couple of things to consider: one, roads are normally superelevated towards the inside. So slippery agents (other than freezing rain, which forms instantenously) will tend to pool towards the inside of the bend, so cutting the inside of a corner might cause a driver to meet such a section of road which he or she would have otherwise avoided. The banking is also not necessarily consistent through the corner - it usually increases towards the inside lip of the road to compensate for the tighter line.

Another factor to consider is that the straightways are typically crowned: sloped on either side of the centerline. This means that on one side of the roadway, a transition has to be made from that crown to the appropriate direction of the corner, which are opposite. In order to make this transition smooth, there will usually be a small section of road just before the corner which is entirely flat (although engineerings will typically try to give it an uphill/downhill slope) which is a usual suspect for slippery conditions. If we offside, we'll be riding over it where we otherwise wouldn't.

akirk wrote:straightening the path assumes either already having the vision / or gaining sufficient vision, and is about stability - as long as the road is clear I see this as no greater risk of debris or oil spills etc. - the stats on increased space being used don't work as the car takes up a car's space where-ever it is - adding road to use, also subtracts road used elsewhere...


But, unless such an unforseen emergency presents itself, what's the point of added stability, especially if we've entered the bend at a reasonably appropriate speed, balanced it properly and started to steer at an appropriate rate? and especially in a car with electronic aids?

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akirk
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Re: Second thoughts on offsiding

Postby akirk » Tue Aug 07, 2018 10:59 am

Astraist wrote:
ancient wrote:But only using one at a time. If the hypothetical oil/ice patch is on only one side of the road, the chances of it being on the near side presumably equal those of it being on the off side (exempt conditions where one side experiences more weather than the other - and then you choose the obviously-safer side; but this scenario dictates that the patch is invisible, from which I assume it is also unpredictable). Given the equal chances, neither side of the road is more likely to be less (or more) slippery than the other and there is not any increased chance of hitting the hypothetical patch by off-siding. So the choice should be to apply less sideways force on the car: Hence yes we should be off-siding.


Yes, I'm assuming the lighting conditions are such that the slippery section of road is not visible. Otherwise, its not unreasonable to assume that if its too small to be noticed - its probably not going to affect the car's handling too adversly.

As for it being equally likely on either part of the bend - I don't know. There are a couple of things to consider: one, roads are normally superelevated towards the inside. So slippery agents (other than freezing rain, which forms instantenously) will tend to pool towards the inside of the bend, so cutting the inside of a corner might cause a driver to meet such a section of road which he or she would have otherwise avoided. The banking is also not necessarily consistent through the corner - it usually increases towards the inside lip of the road to compensate for the tighter line.

Another factor to consider is that the straightways are typically crowned: sloped on either side of the centerline. This means that on one side of the roadway, a transition has to be made from that crown to the appropriate direction of the corner, which are opposite. In order to make this transition smooth, there will usually be a small section of road just before the corner which is entirely flat (although engineerings will typically try to give it an uphill/downhill slope) which is a usual suspect for slippery conditions. If we offside, we'll be riding over it where we otherwise wouldn't.


road profile affects different vehicles in different ways = e.g. bike may be more susceptible to changes in profile than a car. My z3 tramlines more than the M5, so I would tend to drive them differently...

Astraist wrote:
akirk wrote:straightening the path assumes either already having the vision / or gaining sufficient vision, and is about stability - as long as the road is clear I see this as no greater risk of debris or oil spills etc. - the stats on increased space being used don't work as the car takes up a car's space where-ever it is - adding road to use, also subtracts road used elsewhere...


But, unless such an unforseen emergency presents itself, what's the point of added stability, especially if we've entered the bend at a reasonably appropriate speed, balanced it properly and started to steer at an appropriate rate? and especially in a car with electronic aids?


added stability = added speed
added stability = added contingency (e.g. in the event of a blowout)

for me a lot of driving is about adding the ability for speed or contingency - if you can add both, then happy days - otherwise, it tends to be a choice between choosing speed or contingency...

the context being added speed / contingency within the same safety parameters...

Alasdair

Astraist
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Re: Second thoughts on offsiding

Postby Astraist » Tue Aug 07, 2018 2:13 pm

akirk wrote:road profile affects different vehicles in different ways = e.g. bike may be more susceptible to changes in profile than a car. My z3 tramlines more than the M5, so I would tend to drive them differently...


Sure, but I'm referring to its effect on the runoff of slippery substances. It means that both icy patches and spills of oily materials will be more likely on the inner circumference of the corner, so using that as part of an offsiding/cutting maneuver increases the chance (albeit rare in either case) of this happening.

akirk wrote:added stability = added speed
added stability = added contingency (e.g. in the event of a blowout)

for me a lot of driving is about adding the ability for speed or contingency - if you can add both, then happy days - otherwise, it tends to be a choice between choosing speed or contingency...


Exactly, contingency. But for what? Not for cornering capacity at speed because if one intentionally offsiding, one would know better; not for being able to safely stop in the clear road section ahead, because if one offsiding, that's clearly not an issue from the outset; not for defensive purposes (i.e. another road user using more than their fair share of the road) because offsiding isn't performed in the presence of other road users.

So that leaves us with contingency for a sudden, unforseen reduction in road holding. The main cause of that being an unforseen, slippery part of the road. But than, if we're using twice the road width, we're increasing the possibility of hitting such a section of road, which may occur on just one of the two lanes, or just around the centerline.


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