WEBVTT
Kind: captions
Language: en

1
00:00:00.080 --> 00:00:01.680
This is one of those problems
that seems like 

2
00:00:01.680 --> 00:00:05.840
it'd be really complicated to fix,
but turns out to have a simple solution.

3
00:00:05.840 --> 00:00:08.680
But then that solution
turns out to be really complicated.

4
00:00:08.680 --> 00:00:10.280
This is Brienz in Switzerland. 

5
00:00:10.280 --> 00:00:12.240
It's a small alpine village surrounded by 

6
00:00:12.240 --> 00:00:16.000
absolutely beautiful hills and mountains
that occasionally try to kill people.

7
00:00:16.000 --> 00:00:18.800
This whole hillside is slowly
sliding and slipping down.

8
00:00:18.800 --> 00:00:22.280
It can't hold itself up.
Most of the time, it's silent and still.

9
00:00:22.280 --> 00:00:25.600
But occasionally,
a load of heavy rocks will tumble down.

10
00:00:25.600 --> 00:00:29.000
Actually, I feel like "heavy rocks"
isn't really getting the point across.

11
00:00:29.000 --> 00:00:30.400
This is one of the rocks. 

12
00:00:30.400 --> 00:00:34.240
And worst case, it'll travel
across that road

13
00:00:34.240 --> 00:00:37.240
at 10 or 20 kilometres an hour,
sideways.

14
00:00:37.240 --> 00:00:38.640
IN SWISS GERMAN:

15
00:01:51.680 --> 00:01:54.680
The village is safe from
the big individual rockfalls,

16
00:01:54.680 --> 00:01:55.840
it's far enough away. 

17
00:01:55.840 --> 00:01:57.960
The road here, not so much.

18
00:01:57.960 --> 00:01:59.000
It'd be far too expensive 

19
00:01:59.000 --> 00:02:02.200
to build massive protection barriers
all along there. And besides,

20
00:02:02.200 --> 00:02:06.640
the odds of a boulder actually
hitting a car are small. But not zero.

21
00:02:06.640 --> 00:02:07.520
So what you want 

22
00:02:07.520 --> 00:02:11.480
is something that can automatically
detect rockfalls and close the road.

23
00:02:11.480 --> 00:02:13.640
Simple solution: a radar...

24
00:02:13.640 --> 00:02:15.480
and a stoplight. 

25
00:02:15.480 --> 00:02:20.880
So if the radar detects rockfall
in a certain defined area, it triggers

26
00:02:20.880 --> 00:02:26.280
an alarm. The traffic lights go red,
and then the radar tracks the rockfall.

27
00:02:26.280 --> 00:02:29.440
If the rockfall stops or it ends up
in the dam,

28
00:02:29.440 --> 00:02:33.080
then the traffic light switches off,
goes back to normal,

29
00:02:33.080 --> 00:02:34.880
the road is safe to pass.,

30
00:02:34.880 --> 00:02:40.200
If the rockfall ends up somewhere
close to the road, the traffic light

31
00:02:40.200 --> 00:02:43.640
switches to flashing orange,
which means "drive carefully",

32
00:02:43.640 --> 00:02:48.240
because a boulder could be on the road,
or the road could be damaged.

33
00:02:48.240 --> 00:02:52.080
Radar has the large benefit
that it works in all weather

34
00:02:52.080 --> 00:02:53.880
and all visibility conditions.

35
00:02:53.880 --> 00:03:00.600
Radar waves can penetrate fog, rainfall,
snowfall; and hence, works day at night

36
00:03:00.600 --> 00:03:03.640
and in all visibility conditions,
which is needed for an alarm system.

37
00:03:03.640 --> 00:03:07.400
The traffic lights are about
450 meters apart,

38
00:03:07.400 --> 00:03:11.680
which is the area considered as
dangerous for the traffic.

39
00:03:11.680 --> 00:03:18.760
We've got about 40 seconds from detachment
to a rock reaching the road,

40
00:03:18.760 --> 00:03:23.280
and this is just enough for the cars
to escape the dangerous area.

41
00:03:23.280 --> 00:03:27.400
They have to drive a certain velocity,
otherwise they can't get away.

42
00:03:27.400 --> 00:03:30.560
And this is why cyclists
are not allowed on this road.

43
00:03:30.560 --> 00:03:33.520
Here's the complicated bit:
you can't just have this stop traffic

44
00:03:33.520 --> 00:03:36.360
any time the radar detects movement.
Birds would set it off.

45
00:03:36.360 --> 00:03:37.840
My drone would set it off. 

46
00:03:37.840 --> 00:03:43.240
Mischievous kids throwing pebbles
would set it off. On that note...

47
00:03:43.240 --> 00:03:47.000
How do you calibrate something like this?

48
00:03:47.000 --> 00:03:49.040
We don't have a lot of false alarms. 

49
00:03:49.040 --> 00:03:52.960
It's very rare that we close the road
because of something else, for example,

50
00:03:52.960 --> 00:03:56.680
an approaching rain front
that could look kind of similar.

51
00:03:56.680 --> 00:03:59.920
Since this is such an active site,
this is the perfect site

52
00:03:59.920 --> 00:04:03.760
to tune your algorithms
or to develop the algorithms at all.

53
00:04:03.760 --> 00:04:07.200
We installed the radar in 2017,

54
00:04:07.200 --> 00:04:12.960
and after a test period of about a year,
it went live with the traffic lights.

55
00:04:12.960 --> 00:04:17.800
And since installation, we've detected
five and a half thousand events.

56
00:04:17.800 --> 00:04:19.320
From an engineering perspective, 

57
00:04:19.320 --> 00:04:22.440
setting up a radar and a stoplight is the easy part.

58
00:04:22.440 --> 00:04:25.680
The complicated part is working out
 the balance between false positives,

59
00:04:25.680 --> 00:04:28.120
where the road is going to
be closed half the time,

60
00:04:28.120 --> 00:04:32.280
and false negatives, where cars
could get hit by boulders.

61
00:04:32.280 --> 00:04:35.240
Now I haven't seen any rockfalls here
today, and I also haven't

62
00:04:35.240 --> 00:04:36.080
seen the lights change. 

63
00:04:36.080 --> 00:04:41.400
And their logs now have thousands of
rockfalls where the lights did turn red.

64
00:04:41.400 --> 00:04:43.720
So I'd say: they probably
got it about right.

65
00:04:45.200 --> 00:04:47.160
I mean, I know it was too much
to hope for, I was just hoping 

66
00:04:47.160 --> 00:04:49.720
there'd be just a little rock fall
as I finished? Just...

67
00:04:49.720 --> 00:04:52.800
just like a little one.
Not doing any damage.

68
00:04:52.800 --> 00:04:54.280
Just a few.

69
00:04:58.280 --> 00:04:59.680
Let's do that again!

70
00:04:59.680 --> 00:05:02.600
Let's do that again without worrying
 that a rock's going to hit me.