Coincidence?

rjsterry

Last Friday, I bumped into vermin on my inward commute at about 9.20 passing Horseguards on the Embankment. On the way home, we met up again at Vauxhall Bridge. At first, I was surprised at the coincidence given that even with exactly the same routes, given that we seem to ride at similar speeds, you would only need to be a minute or two apart to not see each other.

Then I thought about it some more, and realised that there may be a number of factors that make the probability of meeting the same person on inward an outward journey's more likely. For one, all the traffic lights, tend to cause traffic travelling along the same route to bunch up (like buses), so instead of hundreds of individuals travelling along the same route, there are a much smaller number of 'waves' of traffic that spread out and rejoin at each set of lights - maybe 10 or 20 of these groups on the whole Embankment.

This is where my rather rusty grasp of probability and mathematical modelling runs out, and I was wondering if anyone could come up with a convincing mathematical explanation for why commuter cyclists leaving their homes/offices at apparently random moments end up riding with the same people morning and night.

optimisticbiker

On the same front, how come I often end up drafting the same bus usually both ways up and down the Edgware road? Last week I drafted a #32 reg X322HLL 9 times out of 10 commutes! Again my commute start time is non-deterministic as is the traffic...

clarkey cat

He's obviously harbouring an unhealthy obsession towards you and waits for you. Be careful.

rjsterry

I'm sure we've flushed out some maths geeks in the past - come forth and make yourself known.

mtb-idle

All vermin look the same, it was probably a different rat.

It's a bit like when they announced they had cloned Dolly the sheep and were all billy big bollocks about it I thought WT, what's the point. They all look the same anyway.

rjsterry

vermin is one of the SCR regulars, as opposed to a rodent.

Anyway, some parameters for the problem:

Let's limit rush hour times to 2hrs in the morning 0730-0930 and 3hrs in the evening 0530-0830.
Let's fix journey times at 1 hr.
For the sake of this problem, the Embankment is defined as Battersea Bridge to Blackfriars Bridge inbound and vice versa, and forms the central section of each commuters route.
http://maps.google.co.uk/maps?saddr=Blackfriars+Underpass%2FA3211&daddr=Cheyne+Walk%2FA3212&hl=en&sll=51.49542,-0.13889&sspn=0.040932,0.111408&geocode=Fdj-EQMdSmf-_w%3BFSaOEQMddlr9_w&gl=uk&mra=dme&mrsp=0&sz=14&t=m&z=14
Let's set an average speed of 17mph and a maximum of 27mph.
Finally, there are 25 sets of traffic lights and 5 pelican crossings, if I count correctly - anyone care to take a stab a typical phasing sequence?

SmellTheGlove

Sherlock to the thread..?

notsoblue

I've often thought that RJS. The traffic lights must have some kind of modulating effect. And he probably knows where you live.

The Rookie

If people have a fixed start of work time, assuming they cycle at about teh same speed on the same route (it's commuting so yes!) then they probably travel down any particular road within a 6 minute window.

Assume traffic lights have a 90second cycle (from start of green to next start of green) that means 4 'waves' in that 6minute window, so a 1:4 (25%) chance on any particular day you'd be in the same wave, even if you drop the TS cycle to 60seconds it's a 1:6 chance or just over 16% chance.

I pass the same women going the OTHER way most mornings within about a 200m length of road, which takes me about 25 seconds to travel.....we both know if one of us is late!

Simon

mtb-idle

rjsterry wrote:

vermin is one of the SCR regulars, as opposed to a rodent.

Yeah, I knew that i was being errr... amusing.

rjsterry

MTB-Idle wrote:

rjsterry wrote:

vermin is one of the SCR regulars, as opposed to a rodent.

Yeah, I knew that i was being errr... amusing.

Ah, I see. Well this is all a bit awkward now.

bails87

Like Simon I also see a few regulars, always on (almost) exactly the same bit of road. I know that as I come round a certain corner there'll be a roadie coming the other way. I know that as I go past the petrol station the paperboy will appear out of the alleyway and ride along the pavement and onto the drive of a house.

Because presumably we both leave at the same time and ride at roughly the same speed each day, meaning we're at roughly the same points at the same time each day.

rjsterry

bails87 wrote:

Like Simon I also see a few regulars, always on (almost) exactly the same bit of road. I know that as I come round a certain corner there'll be a roadie coming the other way. I know that as I go past the petrol station the paperboy will appear out of the alleyway and ride along the pavement and onto the drive of a house.

Because presumably we both leave at the same time and ride at roughly the same speed each day, meaning we're at roughly the same points at the same time each day.

This is my point, though: my commute times vary by ± 30 minutes morning and evening, that's quite a big window.

rick_chasey

rjsterry wrote:

bails87 wrote:

Like Simon I also see a few regulars, always on (almost) exactly the same bit of road. I know that as I come round a certain corner there'll be a roadie coming the other way. I know that as I go past the petrol station the paperboy will appear out of the alleyway and ride along the pavement and onto the drive of a house.

Because presumably we both leave at the same time and ride at roughly the same speed each day, meaning we're at roughly the same points at the same time each day.

This is my point, though: my commute times vary by ± 30 minutes morning and evening, that's quite a big window.

Assume everyone travels at the same speed for a moment, and assume all the lights have a fixed time they're red & green - you can narrow the liklihood down quite a lot, since you'd get waves. So say it's 45 secs red 15 secs green, you'd have 30 discreet waves of cyclists for every half hour.

Narrow that down to 10 minutes and you'd have 10 - so a 1 in 10 chance.

etc.

Given that it's discreet, it would tally up to the discreet way you bump into people i.e. exactly in that spot.

veronese68

rjsterry wrote:

This is my point, though: my commute times vary by ± 30 minutes morning and evening, that's quite a big window.

You have a magnetic personality. They are irresistably drawn to you.

Maxticate

You look for reinforcement of your theory of always seeing the same people in the same places and disregard evidence to the contrary perhaps.

Seeing the same person in the same area affirms your belief that you see the same people in the same spot everyday. Maybe some days when you see them they are a little outside of the zone but you remember it later as being in the same spot you always see them. Another positive result. This may happen because you are focussing on other things and not expressly looking out for that person.

The only way to get unbiased data on this would be for one of the head cam wearing crowd to analyse a months worth of commutes with leaving times and see if you really do see the same person at the same point everyday.

clarkey cat

I've seen Veronese on my commute TWICE now and the point at which our commutes cross is entirely perpendicular so the chances of our paths crossing at the same time are pretty remote. Explain that!

Mr Sworld

Veronese68 wrote:

rjsterry wrote:

This is my point, though: my commute times vary by ± 30 minutes morning and evening, that's quite a big window.

You have a magnetic personality. They are irresistably drawn to you.

Nope... It's well know that everyone experiences Groundhog Day for a few seconds each week...

Maxticate

clarkey cat wrote:

I've seen Veronese on my commute TWICE now and the point at which our commutes cross is entirely perpendicular so the chances of our paths crossing at the same time are pretty remote. Explain that!

How many times haven't you seen Veronese on your commute?

clarkey cat

on this commute... about 198 times.

rjsterry

We seem to be veering off a bit - I wasn't asking about bumping into the same (possibly non-commuting) people at the same point each day, I was asking about the probability on any single day of bumping into the same cyclist on inward and outward commutes given no direct relation between us other than that we use the same stretch of road at some point within a 2-3 hr window each way.

I can see that traffic lights tend to bunch people up, so if you are within a couple of minutes of someone, then you'll tend to meet them at the lights at some point, but is there anything else?

clarkey cat

1) the lights bunching people up, as you say
2) people more inclined to take embankment frequently for SCR when other routes are available;
3) people more inclined to travel at a certain time for SCR;
4) people's routines... how many times do you see people on the same train? Much more likely to as only, say 6 an hour as opposed to 20 'waves' of commuters an hour on embankment but same principle.
5) you're looking for it - because you're eyeing people up because of SCR.

vermin

I've just found this thread and think I can clarify the position for you all.

You see, despite his protestations, RJST was clearly lying in wait for me that evening, having spent the whole day hand-wringing over the loss of his scalp and plotting how he was going to retrieve it that evening.

That evening, through the gap in the bushes, he spied me cruising by at a leisurely pace. With eyes glowing red, he set off in hot pursuit and raced past me at something approaching 100mph.

Unfortunately, he found he couldn't maintain something approaching 100mph for very long and, as a result, I still have that scalp. It's in the saddle bag now, if anyone wants it.

:twisted: :twisted: :twisted: :twisted: :twisted: :twisted:

veronese68

clarkey cat wrote:

I've seen Veronese on my commute TWICE now and the point at which our commutes cross is entirely perpendicular so the chances of our paths crossing at the same time are pretty remote. Explain that!

But why does CC always see me first? Is it because:
a. I'm old and a bit slow to react.
b. I'm riding across his bow and concentrating on the trafic around me.
c. he's admiring my unmatched style.
d. He's just a bit more observant than I am.
e. He fancies me and hovers around that junction hoping to catch a glimpse of me as I pass.
f. I ride a big red gate that is hard to miss.g. none of the above.
g. none of the above.
There was a bloke on a black bike with guards and drops at that junction this morning. I had a good look, not a Hewitt. I gave him a nod to say good morning. He probably thinks I was checking him out. Ooops.

roger_merriman

I also see Veronese now and then, again our routes only clip over a tiny distance.

the varibles are my wife who does not leave on time or rather at the same time. I am rather observent so normally spot Veronese though since he's tall and on drops with good lights this makes him easer to spot. most if not all of the other bikes tend to be hivis ladies on hybrids.

notsoblue

roger merriman wrote:

I also see Veronese now and then, again our routes only clip over a tiny distance.

the varibles are my wife who does not leave on time or rather at the same time. I am rather observent so normally spot Veronese though since he's tall and on drops with good lights this makes him easer to spot. most if not all of the other bikes tend to be hivis ladies on hybrids.

They're players of The Game, trying to artificially raise their FCN. Don't be fooled.

clarkey cat

I see a guy on an immaculate Kinesis with guards / brooks saddle / yello ortlieb bag most commutes. Both ways. I see him at Priory Lane on the way in and on the way back at VB. Usually have a chat.