How well do London buses match the timetables? • Hacker News Board

Re: How well do London buses match the timetables?

#21

Post by gpvos » Tue, May 07, 2019, 4:30 PM UTC

vidanay wrote: post #10

Reason077 wrote: post #5

Earlier quoted context omitted.

In London, sometimes a bus will be held at a stop for a minute or three by dispatchers to “regulate the service”. It's annoying when you’re on that bus, but it makes sense to try and avoid services bunching together. (And occasionally when they do end up bunched together, the overcrowded bus in front will wait briefly so the empty bus behind it can pass)

The "El" (Elevated) trains in Chicago will do the same thing. Sometimes you simply stop between stations. Sometimes, it is only 25 ft before a station and you can see your goal in sight.

Why would they stop for regulation (as opposed to the track in front being occupied, which is obviously a good reason to stop at any place) at anything else but a station?

Re: How well do London buses match the timetables?

#22

Post by gpvos » Tue, May 07, 2019, 4:38 PM UTC

jnty wrote: post #6

On trains and planes, my main critieria is that I arrive by the stated arrival time and therefore am pretty unfussed by stories about padding time etc - that's more of a long term structural concern than something that will bother me on the day. I think operators have figured this is all most people really care about over time (perhaps excepting highly competitive routes.) You lose this ability to check timings with…

In Europe, train operators often have a target percentage, like 90%, of trains that must be on time[0] specified in their concession, with a system of fines or bonuses. So they have an incentive to put some padding in their schedules, since that will improve their lateness statistics.

[0] Usually defined as being less than 5 minutes late or so.

Re: How well do London buses match the timetables?

#23

Post by carlob » Tue, May 07, 2019, 4:46 PM UTC

imatworknow wrote: post #2

I wonder whether this is the norm for other cities?

I live in Rome. Here we have a schedule for departures, and real time tracking. The schedule for departures is a lie, meaning that any given departure can be canceled without notice, so unless a bus has already left the terminus you cannot be sure it ever will.

So I'm guessing our public transportation works worse than the one the author describes in Rwanda.

Re: How well do London buses match the timetables?

#24

Post by quenstionsasked » Tue, May 07, 2019, 4:56 PM UTC

vidanay wrote: post #8

I have noticed this paradox when accessing my VPN time based code. More often the time until refresh is >30 seconds than it is <30 seconds (60 seconds between refreshes)

This doesn't hold. The timing of the VPN code widget is not a random variable, but rather fixed. Thus, sampling a random inspection time of the widget has equal probability of being in the 0-30s bucket as it does in the 30-60s bucket.

For a bus, the intuitive explanation is that if you were viewing a timeline, the biggest parts of the timeline would be the "late" buses, and thus you're more likely to "inspect" (arrive at the bus stop) during one of these longer stretches.

Re: How well do London buses match the timetables?

#25

Post by juskrey » Tue, May 07, 2019, 4:57 PM UTC

vidanay wrote: post #8

I have noticed this paradox when accessing my VPN time based code. More often the time until refresh is >30 seconds than it is <30 seconds (60 seconds between refreshes)

This is because refresh can't take negative time.

Re: How well do London buses match the timetables?

#26

Post by juskrey » Tue, May 07, 2019, 4:58 PM UTC

Obviously the bus can't arrive before departure

Re: How well do London buses match the timetables?

#27

Post by theoh » Tue, May 07, 2019, 4:58 PM UTC

devy wrote: post #13

SamBam wrote: post #9

The conclusion of the article seems to be related to the general rule that if, say, a box of nails advertises 1000 nails, the manufacturer will have set the actual average to be higher than 1000 nails so that some large majority of buyers will always have at least 1000 nails in the box. (I seem to recall an A-Level stats question on my exam asking what the average should be, to ensure that 95% of buyers received at l…

> the general rule that if, say, a box of nails advertises 1000 nails, the manufacturer will have set the actual average to be higher than 1000 nails so that some large majority of buyers will always have at least 1000 nails in the box. This is actually not a good analogy. These days nails are mass produced and quality controls are good to ensure each has the same rough shape and weight +/- by a few percentage points…

"Overs and unders" are still a thing in manufacturing. Up to 10% either way.

e.g. https://support.discmakers.com/hc/en-us/articles/209954927-M...

https://www.lumi.com/blog/explaining-overs-unders

http://www.admorefolders.com/overunder.html

Re: How well do London buses match the timetables?

#28

Post by vidanay » Tue, May 07, 2019, 5:00 PM UTC

gpvos wrote: post #21

vidanay wrote: post #10

Earlier quoted context omitted.

The "El" (Elevated) trains in Chicago will do the same thing. Sometimes you simply stop between stations. Sometimes, it is only 25 ft before a station and you can see your goal in sight.

Why would they stop for regulation (as opposed to the track in front being occupied, which is obviously a good reason to stop at any place) at anything else but a station?

My guess would be some sort of naive algorithm that doesn't account for such proximity.

Re: How well do London buses match the timetables?

#29

Post by michjedi » Tue, May 07, 2019, 5:03 PM UTC

carlob wrote: post #23

imatworknow wrote: post #2

I wonder whether this is the norm for other cities?

I live in Rome. Here we have a schedule for departures, and real time tracking. The schedule for departures is a lie, meaning that any given departure can be canceled without notice, so unless a bus has already left the terminus you cannot be sure it ever will. So I'm guessing our public transportation works worse than the one the author describes in Rwanda.

Interesting! How do you usually plan your journey in Rome, and how often does your journey work out like the plan?

Re: How well do London buses match the timetables?

#30

Post by johnchristopher » Tue, May 07, 2019, 5:05 PM UTC

gpvos wrote: post #22

jnty wrote: post #6

On trains and planes, my main critieria is that I arrive by the stated arrival time and therefore am pretty unfussed by stories about padding time etc - that's more of a long term structural concern than something that will bother me on the day. I think operators have figured this is all most people really care about over time (perhaps excepting highly competitive routes.) You lose this ability to check timings with…

In Europe, train operators often have a target percentage, like 90%, of trains that must be on time[0] specified in their concession, with a system of fines or bonuses. So they have an incentive to put some padding in their schedules, since that will improve their lateness statistics. [0] Usually defined as being less than 5 minutes late or so.

And in Belgium those 5 minutes only count at the end of the line. It means that the train can be 15 minutes late and miss connections but it won't be considered late if it made up for the delay upon arriving at the terminus.