Cyclists approaching blind crests and corners and overtaking vehicles

Here are a few posts I have made recently concerning the safety aspects involved in cycling towards blind corners and crests.

I am not suggesting that every-one 'do as I do'. I am ultyra conservative, trying to look after my own  life, and the lives of the people in the over-taking car and also those in any unseen cars that come inot view half way through a bad overtake.


My outlook on cycling is to have fun, enjoy the thrill and the fresh air in my face, the satisfaction of completing a long ride. But I don't expect motorists to be perfect. I do expect lots of very bad behaviours from motorists. I do not get angry with them any more. I have just altered my methods of riding so I increase my chances of getting home safely. 

Riding is a risk. Riding on roads is even more risky. We have to live with the bad drivers. We can all choose different ways of doing that. I choose to ride defensively.

So here are a few of my posts that I have gathered together in one thread. 

I apologise if they seem to be very long. You don't have to read them! 

I look forward to any comments, and apologise in advance for the few places where my frustration with fellow riders, and also a any place where I may offend by suggesting riders could, or should, ride more defensively.

We all do it in our own ways. And as with any discussion, there is always the possibility that either myself, or some of the readers of my posts, have a think about things and maybe come to a different way of understanding and partaking in our hobby.

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OK, first post is the simple theory, or the 'maths' of the distances required to overtake safely.

It is trying to explain a concept I used in my physics class when applying the physics of motion to one aspect of driving safely - overtaking. I called it the 'Double the Distance' method to decide whether it is safe to overtake . . .

So imagine two cars coming towards each other on a perfectly straight road with no corner or crest between them. They can see each other.

You are driving one of those cars. You are driving at 80km/hr.

80 km/hr is about 22m every second.

I did an experiment with a mate of my mine a couple f years ago. I was trying to show him how far a car travels in doing a normal overtake of a bicycle.

I put my bike on the side of the road, and we drove back about half km and did a U-turn. He was in the driver's seat. I asked him to drive at 80km/hr and then when he saw my bike to 'overtake' it as if it was a cyclist on the road.

He performed what I would say was a pretty good simulation of overtaking a stationary bike.

I spotted a bush on the side of the road where he first started that manoeuvre, and another bush/tree where he crossed back to the left of the centre line.

We got out and paced out the distance. It was about 200m.

That makes sense, if you consider that a normal move over to the right side of centre line at 80km/hr, without swerving, takes about 4 seconds, and 4 x 22m = 88m.

Add the same to get back to the left - 176 metres. 200 metres to be safe say, and easier to talk about.

Now of course a bike rider is . . riding. Maybe quite fast. But not so fast going up a hill. (Could be very fast going down a hill towards a blind corner, as I was just 9 months ago in the Barossa Valley and a semi-trailer nearly wiped me out when a 4x4 came around that blind corner! I 'woke up' just in time and hit the dirt. 2 seconds later the semi flew past with his two wheels on the white line. I had been riding on the right of that same line!)

So 200m is just a an estimation for the moment.  (It should be 176m plus any distance the bike moves during the overtake.)

Now getting back to that situation where you are driving towards another car on a straight flat road, both doing 80km/hr.

In 8 seconds you will travel towards that car 176m.

And in the same time the other car will travel towards you 176m.

So when the two cars are at a distance apart of 2 x 176m (double the distance) = 352m apart, then 8 seconds later you will have the other car passing you.

Now put yourself in the situation where there is a blind crest somewhere between yourself and that oncoming car. The maths is still the same! In 8 seconds from the start, the two cars will pass each other.

Now put yourself on the wrong side of the road for that 8 seconds, because when you overtake a stationary obstacle on the road, like a cow, or a fallen tree , . . or a stationary bike, you will be on the wrong side for 8 seconds. At the end of that 8 seconds you are now back on the left side and there will be no problem, the other car will go past just as you returned to the left. All good.

But what if you tried doing the same thing when there was less than 352m between the two cars! Now you would still be on the wrong side of the road - and unless you did some drastic action with the steering wheel, and got back to the left far quicker than normal, there is going to be a collision.

And that is exactly what can happen when-ever you try overtaking closer than 'double the distance' it takes you to complete the overtake of the bike, cow, rubbish on road, . . .

Let's say you can see the top of the crest and you estimate it to be 200m away.

No probs, I can get around that bike and be back on the left in 176m. That means I have 24m up my sleeve! All good. Let's do it!

That's what most drivers think. Or maybe I am being unkind. Maybe I should say 80% of drivers, based on what I have observed myself, and in the videos I have been seeing on this thread too. But 80% and most are about the same!

Well, if the 'other car' I have been talking about is actually a hidden car just 50m behind that crest, let's work out what is going to happen . . .

The two cars are now only 250m apart. They both doing 22m/sec. So how long before they meet? Well half of 250 = 125m. and 125/22 = 5.7s seconds.

So you have only had time to travel 5.7 x 22 = 125m. You are still on the wrong side of the road!

The other car has come over that crest and travelled another 75m down the hill towards you. (50m behind crest + 75m after crest = 125m) It has come past your point of 'return to the left' by 75 - 24 = 51 metres!

That's a very bad situation to be in - for you, the other car and . .  the cyclist(s) you were overtaking.

A lot of maths there! 

But the simple thing is - estimate how far it is going to take to get around that bike and at least double the distance to be safe.


There is a problem with that simplistic idea, because it really only works when you are driving at typical road speeds - say 80km/hr or 100km/hr. (Obviously at 100km/hr it is going to take more distance than at 80km/hr)

But if you have slowed right down to the bikes speed, you might be able to get around in a shorter distance than at 80km/hr, with heavy use of the throttle to get a quick acceleration. I won't bother with the maths because it is so variable, depending on the gradient of the hill, the traction of the wheels, the power/weight ratio of your vehicle . . . 

And of course the oncoming car, the one that you cannot see, could be doing 100km/r, or even 110km/hr, so 'chewing up' far more road than a car at 80km/hr.

So if you can get past a slow moving cyclist in a much shorter distance than you would at 80km/hr, or 100km/hr then in fact you really need a "Treble the distance" or a "Quadruple the distance' rule for your very much shortened overtake. Because that hidden car is probably gong a whole lot faster and will cover a lot more distance in the same time it takes you to get past the cyclist.

But basic fact is - IT IS NOT GOOD ENOUGH TO GET BACK ONTO LEFT SIDE JUST BEFORE THE CREST OR CORNER!


And most drivers only have one thing in mind - can I get back to the left before that corner - as in 80% of the drivers in these videos on this thread!

So, what has that to do with being a cyclist. Surely all that is just what a motorist needs to know.  Surely all we cyclists have to do is mind our own business and just keep riding towards that blind corner, or keep slogging up the hill towards the blind corner, and just let the passing car/truck do what they have to do.

Well all good if they do the right thing. If they realise they are too close to the blind spot up ahead and stay behind until they are past that crest or corner and can see well up the road ahead.

In my experience about 80%, maybe more, drivers don't overtake safely. They just manage to get back to the left when they have almost reached the blind spot.

As a result I am pretty sure cyclists are being injured or killed when they suddenly realise they are in trouble, and have to swerve back to the left to avoid a head-on collision.

How do you tackle this issue?

Do you think that if a car has managed to get back to the left just before the crest, or corner, and no car has come over the top/around the corner, then it was a safe overtake? And so you were never in any danger?


My key comments which I have deleted from the other thread:

My wife and I drove to Norton Summit and Uraidla the weekend before the TDU. There were lots of people out riding. I noticed how little space there was to the left of the fog line on most of the roads we drove on. I also noticed that whenever there was a bit of space, cyclists moved over and often slowed down to let as many cars as possible pass where it was safe for us to do so.

listening on the radio this morning to locals complaining that they have to drive to work on roads with cyclists, I note that on the day I was there, i and other car users were contributing to the local economy, and so were the cyclists.. I think a number of places were very busy with customers who did not live in those towns, on both two and four wheels. Even though I was on four wheels, the two wheel people added to the atmosphere.

On being asked to clarify, and further comments about driver training, I added:

I guess my points were:

  1. cyclists have to be in the main lane because the road has not been designed or built with any alternative
  2. people complain about other people impeding on their economic activity without noticing those same other people are contributing their own economic benefits.
I have been supervising driver for a few learner drivers. I don't recall specifically saying "double the distance", but I have definitely reminded them that there could be a car or truck coming the other way going at least as fast as they are. Also a cow, kangaroo or tree branch just round the corner. these are bigger threats on that blind bend than a cyclist travelling in the same direction as me, because no matter how slowly they are riding, the surprise cyclist had already gone round the bend before I could see that bend.

Hi Scott, thanks for 'coming over' to this new thread.

In reference to your first point you say that "cyclists have to be in the main lane".

Well this I disagree with entirely. Cyclists have a choice on where they are on the road. 

I choose the safest place.

a) The safest place for myself,

b) the safest place for an overtaking car that has made a bad choice to overtake me when it is not safe to do so, risking a head on collision with an oncoming car from a blind crest or blind corner, and

c) the safest place for that unsuspecting vehicle, whether it be a car, bus, truck or cyclist that comes around the corner ahead, or over the crest, to be met with another vehicle in a head on collision situation.

As far as the cyclist being overtaken is concerned, they are at great risk of being hit by the overtaking car. The driver of that car might decide to save their own neck by swerving left to avoid having a head on collision. And of course in so doing they wipe out the cyclist!

So whenever I am in the last 200m approaching a blind crest, or in fact by checking my mirror before I get to that last 200m and determining that I will be in that part of the road by the time the car coming from behind reaches me, which might be not for another 5 or 8 seconds, I just move right over out of harms way - over to the left enough so that car does not have to go over to the wrong side of the road to get past me.

That way no-one is at risk of being put into a dangerous situation. I am doing as I said in my first post on this thread, not only looking after my own safety, but also the safety of others.

And this is as it should be. All road users have a responsibility towards all other road users, not only themselves.

I move right over out of harms way based on my observations over the last 5 years since I have resumed road cycling - about 80% of drivers do not leave room ahead for an oncoming car to come over the crest or around the blind corner. They think they will always be able to do a last second hard swerve to the left to avoid a collision. Well maybe - if the left of the road was not being used.

But what if I am there on my bike?

Well I make sure I am not there on my bike. And I make sure I never was there for them to avoid in the first place. They do not have to cross the double lines.

Problem solved. Simple.

I am sure I have saved my life several times over the last three years, the latest one being just last April, up in the Barossa, and another one I can remember in Tasmania recently involving a very wide boat trailer going around a left hand corner! 

And no doubt possibly saved some head on collisions too.




this is my post from the other discussion, no need to reply again.

John, that's a big explanation and you sort of lost me half way through, but I couldn't help thinking about your other comment ... "Unfortunately this is the classic case of cyclists gambling with the skills and attitudes and psychological health of drivers." With that double distance thing, you're assuming skills and & attitudes & psycho health of drivers.

I was up in the Hills with a car a week or two ago and wrote on this forum about my experience with cyclists. I was patient through Old Gorge Rd, but increasingly frustrated with the ute behind trying to get up my ass and/or trying to pass everyone (I had about 20-30 cyclists in front of me so I can only image the guy in the ute was going to do us both in one go, or get someone killed).

As a cyclist, I had an incident with some young kids yesterday too. At the Zoo on Frome Rd, heading out of the CBD, they were trying to overtake me on the bridge before the roundabout, so in that case I just blocked of the road and went through the middle of the roundabout, but in the Hills, there is so much more room for cars to go wide, so you can only hope they're skilled and have the right attitude. (the lights were red at Melbourne St so I had a quick word to the boys and they couldn't even distinguish between the cycle lane and the 1 meter rule).

Up until recently my thoughts were concentrated on the approach to a blind corner or crest.

My strategy is this -

 - blind corner/crest up ahead. I am within 200 metres of said hazard, or approaching that 200m 'danger zone' . . .

 - Check mirror. 
      1) No cars approaching from behind that will likely be overtaking me before I reach the apex of the crest or corner. Keep ridng as is, on road, but monitoring mirror to make sure situation does not change.

       2) A vehicle approaching and close enough that it will reach me before the crest/corner, or soon after crest/start of corner . . .
            . . . . Move right over so that it can overtake without having to cross centre line and still leave safe passing distance of myself and bike. That might mean leaving the bitumen.

I have been doing this for the last three years or so and with excellent results. I have only once been caught out when I happened to be daydreaming as I was speeding down a hill, enjoying the wind in my face, and failed to see a semi approachng from behind and accelerating down said hill. I heard the roar of his motor, 'woke up' looked ahead and saw a blind corner at the bottom of the hill. I just managed to hit the dirt about two seconds before the semi flew past, (he would have hit me if I was still on the bitumen).
The reason being that just as I hit the brakes to get off the road a four wheel drive came around that blind corner. There was never going to be enough room for a bike, a speeding semi and a four wheel drive!

Anyway, that was a digression. Several times my method described above has allowed  vehicles to cross at my position with me safely out of the way. It works.
Many times no car has come around the bend or over the hill, and you could say I had wasted my time and effort. I don't care. It only needs to save my life once and I am very happy to do this 1000 times or more!!

But just recently, maybe after analysing the death of a rider participating in the Sydney to Melbourne 1200km ride just a few weeks ago, I relaize that exiting a blind corner, or blind crest, is really the same thing.

If the crest or corner is prolonged, then you are blind to vehicles approaching from behind for quite a long distance. Just as they cannot see you, you cannot see them. And possibly the same goes for you being able to see vehicles approaching from in front.

So you really need to be on your guard, checking both up the road in front, and behind, using your mirror, until you are well away from that blind corner/crest!

If riders realised these dangers, and had a mirror, and used it, and had these self preservation strategies, and used them, then I believe there would be a lot less cyclist deaths.

Thank You John for starting this thread and contributing your very sensible ideas.

For me, this boils down to a simple rule “don’t unnecessarily antagonise or inconvenience others”. So, when riding uphill, its nearly always best to ride single file, and as far to the left as practical. In other words, slower traffic to the left and faster traffic to the right. (This is essentially what the traffic laws always stated, until they started to carve up the road to put in traffic lanes and white lines.)

Having said that, there are times when cyclists need to occupy the lane, and deliberately prevent vehicles from overtaking. If I judge an overtaking manoeuvre to be unsafe, I will make that clear to the driver behind, and make sure they have slowed to my speed. Then as soon as it is safe to do so, I will move to the left to allow them to pass. The same applies on winding descents, where I need the full lane for my own safety. In that case my speed is likely to match the safe speed for vehicles, so I will not have delayed them anyway.

Thanks Bill.

I agree with everything you said except for maybe where you are a bit ambiguous in the last paragraph. 

I also like to 'take control' of the road when speeding down hill, to make sure the driver behind does not attempt an overtake until I deem it safe. We agree on that.

But I also agree on you comments about climbing up hills. About moving right over to the left to allow faster cars to go past. I would not attempt to 'take control' going up hills, because as I have said in earlier posts on this thread, roughly 80% of drivers would not take any notice of me being in the middle of the left lane. They will just (swear and honk) and overtake anyway.

Here is another idea I have used too.
There is one quite steep climb I sometimes do called Hill Road, just a bit north of Kersbrook, that cuts across to the next valley to the east.

Near the top there is particularly steep section gong around a blind corner to the left. But there are two reasons it is particularly nasty -

 - almost no dirt verge on the left side, or very rocky and rutted. So tricky to stop and dismount safely.

- And once dismounted it would be very difficult to get going again, especially for me (old and heavy), and be doing that on a blind corner!

So I dismount, watch and listen carefully that no cars are approaching in either direction, and then walk my bike across the narrow road to the nice wide flat gravel verge on the other side!

Then I can get back on the bike (not so steep on outside of the bend) and ride around that corner, well off the bitumen, and with a good view up around that left hand bend. 

The other advantage of being on the right side of the road, on the gravel verge,  is that cars coming in either direction can easily see me from quite a long way off! So no nasty surprises, especially for a car coming up around the fairly sharp left hand bend from behind.

This is an example of the tactic I found on the Google, from an American cyclist. He called 'make yourself invisible' to cars.

By that he means that even if the driver does not see you (as if you were draped in an invisibility cloak lol) then it does not matter. You are completely safe because you are not on the road anyway!

I do that a lot when I choose to ride on bike paths and shared paths.

But I do like hitting the highways too. I choose the safer routes, and the safer times of day. Or routes with a nice wide bike lane.

Not sure where the ambiguity is in my last paragraph.

Its a while since I've ridden in the Kersbrook area, but I think I can point to a similar situation at the intersection of Main South Rd and Pedlars Rd, south of Pedlars Creek and near the Southern Waste Depot. Here there is a curve in the main road at the crest of a hill. Coming from Victor Harbor, I need to do a right turn here onto Pedlars Road in order to avoid the narrow Pedlars Creek Bridge, and get onto the McLaren Vale/Seaford bike path. Situations like these are an anomaly that should be fixed ASAP. Cyclists and Pedestrians shouldn't have to invent their way around these dangerous locations.

Sorry, my bad. Brain just getting a bit fuzzy. But now, reading it a bit slower and more thoughtfully, I can see you were not really suggesting taking control of the lane going up hill, after everything you had already said before  . . . . "nearly always best to ride single file, and as far to the left as practical."

Yes, we need to be on the alert not to get ourselves into danger. There are many places around the city and country where roads were built with only motorists in mind.

Sometimes I see that things are a bit dangerous ahead, whether it be no real safe way to get where I want, or too much traffic all around, and I just ride up onto the footpath, riding slowly of course, and 'make myself invisible' to the cars again lol.

Sometimes at major intersections controlled by traffic lights I just use the pedestrian buttons. e.g. the Main North Road / Montague Road intersection. I need to get diagonally across that intersection, following the Dry Creek paths, so it's much safer to just use the pedestrian buttons and wait for the little green 'man' to help me get across in two stages.

What they call a Hook turn, but I use the pedestrian button to get protection from the two left hand turn lanes next to me. Must annoy the cars a bit because it forces them to wait another 60 seconds or so before they can turn left. Too bad.

Just to round out the conversation.

On the idea that you should be invisible, I'd put it slightly differently, based on my experiences of first riding in Adelaide 50 years ago: "Never trust a motorist."

(1) They may not have seen you

(2) They may not give way (when they should)

(3) They may not respect your right to be there

I must say, the sorts of apologetic, almost self-loathing ideas portrayed in this discussion are what keeps the attitude towards cyclists in the "dark ages" in Australia.

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