[SystemSafety] Change of passenger warnings on Hamburg subway from today.

[Steve Tockey]

I doubt seriously this is going to make any difference. I frequent subway
systems around the world: Beijing, Shanghai, San Francisco's BART,
Washington DC Metro, Paris Metro, Tube in London, etc. In all cases,
whether the "doors closing" warning is verbal or beeps, it simply doesn't
matter. The frequency of someone getting stuck in a closing door is the
same everywhere. So while they may think it will make a difference, in
practice it won't. What they need to do is adjust their schedule to allow
for a certain percentage of such delays and just go with that. They will
have to deal with the delays no matter what...


-- steve



-----Original Message-----
From: Karsten Loer <k.loer at gmx.de>
Date: Monday, February 17, 2014 12:58 AM
To: "systemsafety at TechFak.Uni-Bielefeld.DE"
<systemsafety at TechFak.Uni-Bielefeld.DE>
Subject: [SystemSafety] Change of passenger warnings on Hamburg subway
from	today.

Dear colleagues,

after having enjoyed the inspiring discussions on this list for several
years now, mainly passively, I think I can contribute an interesting topic
today:

Hochbahn, the operating company of Hamburg subway, decided that from today
on the natural language warnings „zurueckbleiben bitte“ („stay clear from
the train“), which used to warn passengers about closing doors of the
train that is imminent to depart, will be replaced by a series of beeps.

Warnings are broadcast at the end of the stop, and are initiated by the
driver after she/he has checked (by means of a set of monitors that are
installed in the cockpit and/or in an area of the platform where the front
of the train comes to a hold) that all doors are clear of passengers.

The old warnings, which had been in operation for several decades,
consisted of a natural language message that was broadcasted via the
public announcement system of the subway station. For newer train (series
DT4 and DT5) this was a recording in a friendly and polite female voice,
for the older DT3 train series these messages were read out by the train
driver at each stop (— so as a side effect travellers were able to learn a
lot about the train driver’s gender, nationality and current mood).
These warning messages were complemented by a series of short beeps at the
train doors.

The new warnings are just an extended series of short beeps at the train
doors. 

The justification given by Hochbahn is as follows:

Apparently, over the years some people were conditioned to interpret the
old natural language warnings to stay clear of the train as a prompt to
speed up an try to get into the train.

As a consequence, people would get trapped in train doors; with a
potential of causing injuries to themselves and delays to the train (in
the new DT4 and DT5 train series the doors will open automatically, if a
certain degree of resistance is detected during the closing process; in
the old DT3 trains the doors need to be opened by the train driver, if
she/he becomes aware of the problem via video screen).

This causes a delay at the station. As a consequence, trains need to go
faster to catch up  with the timetable. This, in turn yield an increase of
power consumption which accumulates to up to 700.000€ (about 1 Million
USD) per year. (Well, from personal experience asa frequent traveller on
these trains, I would have thought the main concern of faster going trains
would the safety of standing passengers who tend to bounce back an forth
due to the higher accelerations; but that matter is not mentioned anywhere
in the press statement.)

In summary, I see three arguments that are raised by the operator to
justify the need for the change of warning announcements:

(1) preventing passengers from getting trapped in doors of a train that is
about to leave,
(2) reducing the frequency of disturbances of the time schedule, as a
consequence of (1), hence, allowing trains on route to travel at lower
velocity and
(3) saving costs if operations as a consequence of (2).

As a safety analyst and concerned passenger I would like to add to this
list of arguments: (4) increasing the level of comfort/reducing the
potential of falls of standing passengers as a consequence of (2)


Perhaps there are other experts on this list who also doubt that changing
the warnings from a combination of spoken platform announcements and
audio-signals on the train to just audio-signals on the train will have
the desired effect?

I wonder how long it will take for people to adapt their habits and react
the door signal alone (Pavlov-effect)?

Maybe it is also worth thinking about the side conditions:
The subway trains in Hamburg operate very frequently and reliably; usually
every 3-5 mins during the peak times (7am through 9pm), and every 10 mins
at nighttime.
So one might wonder why people are prepared to take the risk of getting
injured despite the next train arriving soon.

I wonder if people’s behavior would be likely to change if the imminent
arrival of the next train would be made visible, e.g. as is done on London
underground (although I am not sure if the motivation might be different).
In Hamburg this information is only displayed AFTER the current train has
left the platform.

Many greetings from Hamburg!

Dr. Karsten Loer

Dr. Loer system safety consulting
http://www.dr-loer.eu
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