I see that many people on social media have pointed out the large
discrepancies in reports of crowd size at yesterday’s protest
against the Population White Paper. Variations in estimates always
accompany any outdoor event unless it’s a ticketed one.
My earlier
article quoted the organisers’ figure of 4,000 to 5,000, a
figure they announced at least twice during the rally itself. My
own calculations — which I completed only after publishing the
earlier article indicate that 3,000 to 4,000 may be more
accurate.
Here’s a Facebook mention of 5,000 by the emcee of the event:
They may well be right because estimating crowd size is more art
than science. But here I am going to show you how I arrived at my
own figure.
First, I used a satellite image of Hong Lim Park from Google maps.
That’s the image above. You will see at the bottom left corner that
Google provides a scale. Just in case Google’s scale is a bit off,
I also looked up OneMap’s map
of Hong Lim Park. It is shown below:
I have no reason to doubt the scale. Both maps show the lawn area
of Hong Lim Park — bound by the inner foot path — to be about 65
metres square, with one corner eaten up by the community club’s
stage.
During the rally itself, I moved around a fair bit, from the front
of the crowd to the back and up the overhead bridge across New
Bridge Road (far left of maps), observing the approximate density
at several points. I also took a number of photographs so that I
have a record of density. Two examples are below.
Photograph A (which you can click on to enlarge) was taken close to
the metro station exit. It shows the back of the crowd. The
footpath is visible. The tent where the rally speakers were is away
to the left of the photograph. In fact you can see a
gradient: the umbrellas are denser at the left of the photo
(nearer the tent) than at the right edge. In the background is the
community club stage, but don’t be mistaken, the people there are
not the organisers and speakers; they are the audience, taking
shelter from the drizzle. There are about 100 of them on the
community club stage.
At the top left of the photo you will see a smaller group on the
balcony of the community club. I reckon there are about 30 persons
there.
From photo A, my estimate is that at the back of the crowd, the
density is about 0.7 persons per square metre. That is, there are
about 2 persons for every 3 square metres.
Photograph B (which you can also click to enlarge) is taken about
10 metres from the front of the tent.
Here, people are standing more or less shoulder to shoulder, but
spaced about arm’s length from the person in front. This gives a
density of about 1.5 persons per square metre, that is, about three
persons for every two square metres.
The graphic below has various boxes laid over the Google map of
Hong Lim Park lawn, coloured for their density. The locations of
photographs A and B are marked too. The location of the speakers’
tent is outlined in blue.
The calculation below is so simple and obvious, a Primary 6 pupil
can do it.
Naturally, estimating crowd size cannot be achieved with total
precision. Moreover, people were coming and going (especially as
the drizzle waxed and waned), so an estimate can vary depending on
when the estimate is made.
One could even say that because of the coming and going, the number
present at any given time is not the total who came by and
spent some time
at the rally.
But an exact count is not necessary. The crowd is quite evidently a
sizable one, and considering that the climate of fear is not yet
completely dispelled, it would be foolish to dismiss the
significance of the event.
http://yawningbread.wordpress.com/2013/02/17/crowd-numbers-at-population-protest/
