0:00:01.725,0:00:04.642 Hi. I'm here to talk about congestion, 0:00:04.642,0:00:05.996 namely road congestion. 0:00:05.996,0:00:08.257 Road congestion is a pervasive phenomenon. 0:00:08.257,0:00:11.117 It exists in basically all of the cities all around the world, 0:00:11.117,0:00:13.065 which is a little bit surprising when you think about it. 0:00:13.065,0:00:16.028 I mean, think about how different cities are, actually. 0:00:16.028,0:00:17.790 I mean, you have the typical European cities, 0:00:17.790,0:00:20.782 with a dense urban core, good public transportation 0:00:20.782,0:00:23.237 mostly, not a lot of road capacity. 0:00:23.237,0:00:25.686 But then, on the other hand, you have the American cities. 0:00:25.686,0:00:28.477 It's moving by itself, okay. 0:00:28.477,0:00:31.483 Anyway, the American cities: 0:00:31.483,0:00:34.411 lots of roads dispersed over large areas, 0:00:34.411,0:00:35.870 almost no public transportation. 0:00:35.870,0:00:38.080 And then you have the emerging world cities, 0:00:38.080,0:00:39.606 with a mixed variety of vehicles, 0:00:39.606,0:00:42.148 mixed land-use patterns, also rather dispersed 0:00:42.148,0:00:44.747 but often with a very dense urban core. 0:00:44.747,0:00:47.149 And traffic planners all around the world have tried 0:00:47.149,0:00:50.803 lots of different measures: dense cities or dispersed cities, 0:00:50.803,0:00:53.354 lots of roads or lots of public transport 0:00:53.354,0:00:56.140 or lots of bike lanes or more information, 0:00:56.140,0:00:59.934 or lots of different things, but nothing seems to work. 0:00:59.934,0:01:02.937 But all of these attempts have one thing in common. 0:01:02.937,0:01:05.288 They're basically attempts at figuring out 0:01:05.288,0:01:08.615 what people should do instead of rush hour car driving. 0:01:08.615,0:01:11.727 They're essentially, to a point, attempts at planning 0:01:11.727,0:01:14.929 what other people should do, planning their life for them. 0:01:14.929,0:01:17.381 Now, planning a complex social system 0:01:17.381,0:01:20.456 is a very hard thing to do, and let me tell you a story. 0:01:20.456,0:01:23.183 Back in 1989, when the Berlin Wall fell, 0:01:23.183,0:01:25.805 an urban planner in London got a phone call 0:01:25.805,0:01:28.355 from a colleague in Moscow saying, basically, 0:01:28.355,0:01:30.873 "Hi, this is Vladimir. I'd like to know, 0:01:30.873,0:01:33.895 who's in charge of London's bread supply?" 0:01:33.895,0:01:35.548 And the urban planner in London goes, 0:01:35.548,0:01:37.518 "What do you mean, who's in charge of London's — 0:01:37.518,0:01:38.789 I mean, no one is in charge." 0:01:38.789,0:01:40.671 "Oh, but surely someone must be in charge. 0:01:40.671,0:01:44.327 I mean, it's a very complicated system. Someone must control all of this." 0:01:44.327,0:01:47.433 "No. No. No one is in charge. 0:01:47.433,0:01:50.034 I mean, it basically -- I haven't really thought of it. 0:01:50.034,0:01:52.623 It basically organizes itself." 0:01:52.623,0:01:55.200 It organizes itself. 0:01:55.200,0:01:58.043 That's an example of a complex social system 0:01:58.043,0:02:00.771 which has the ability of self-organizing, 0:02:00.771,0:02:03.359 and this is a very deep insight. 0:02:03.359,0:02:06.672 When you try to solve really complex social problems, 0:02:06.672,0:02:08.388 the right thing to do is most of the time 0:02:08.388,0:02:09.979 to create the incentives. 0:02:09.979,0:02:11.923 You don't plan the details, 0:02:11.923,0:02:14.543 and people will figure out what to do, 0:02:14.543,0:02:16.403 how to adapt to this new framework. 0:02:16.403,0:02:19.894 And let's now look at how we can use this insight 0:02:19.894,0:02:21.530 to combat road congestion. 0:02:21.530,0:02:23.762 This is a map of Stockholm, my hometown. 0:02:23.762,0:02:27.403 Now, Stockholm is a medium-sized city, roughly two million people, 0:02:27.403,0:02:30.192 but Stockholm also has lots of water and lots of water 0:02:30.192,0:02:33.469 means lots of bridges -- narrow bridges, old bridges -- 0:02:33.469,0:02:36.504 which means lots of road congestion. 0:02:36.504,0:02:40.144 And these red dots show the most congested parts, 0:02:40.144,0:02:42.721 which are the bridges that lead into the inner city. 0:02:42.721,0:02:45.247 And then someone came up with the idea that, 0:02:45.247,0:02:47.084 apart from good public transport, 0:02:47.084,0:02:49.685 apart from spending money on roads, 0:02:49.685,0:02:53.900 let's try to charge drivers one or two euros at these bottlenecks. 0:02:53.900,0:02:56.824 Now, one or two euros, that isn't really a lot of money, 0:02:56.824,0:02:59.481 I mean compared to parking charges and running costs, etc., 0:02:59.481,0:03:02.199 so you would probably expect that car drivers 0:03:02.199,0:03:04.637 wouldn't really react to this fairly small charge. 0:03:04.637,0:03:05.937 You would be wrong. 0:03:05.937,0:03:09.965 One or two euros was enough to make 20 percent of cars 0:03:09.965,0:03:12.349 disappear from rush hours. 0:03:12.349,0:03:15.900 Now, 20 percent, well, that's a fairly huge figure, you might think, 0:03:15.900,0:03:18.107 but you've still got 80 percent left of the problem, right? 0:03:18.107,0:03:19.976 Because you still have 80 percent of the traffic. 0:03:19.976,0:03:23.243 Now, that's also wrong, because traffic happens to be 0:03:23.243,0:03:25.935 a nonlinear phenomenon, meaning that 0:03:25.935,0:03:29.076 once you reach above a certain capacity threshold 0:03:29.076,0:03:32.244 then congestion starts to increase really, really rapidly. 0:03:32.244,0:03:34.704 But fortunately, it also works the other way around. 0:03:34.704,0:03:38.035 If you can reduce traffic even somewhat, then congestion 0:03:38.035,0:03:41.664 will go down much faster than you might think. 0:03:41.664,0:03:44.555 Now, congestion charges were introduced in Stockholm 0:03:44.555,0:03:49.159 on January 3, 2006, and the first picture here is a picture 0:03:49.159,0:03:53.142 of Stockholm, one of the typical streets, January 2. 0:03:53.142,0:03:56.955 The first day with the congestion charges looked like this. 0:03:56.955,0:03:59.875 This is what happens when you take away 0:03:59.875,0:04:01.940 20 percent of the cars from the streets. 0:04:01.940,0:04:04.650 You really reduce congestion quite substantially. 0:04:04.650,0:04:08.308 But, well, as I said, I mean, car drivers adapt, right? 0:04:08.308,0:04:10.810 So after a while they would all come back because they 0:04:10.810,0:04:12.758 have sort of gotten used to charges. 0:04:12.758,0:04:16.434 Wrong again. It's now six and a half years ago 0:04:16.434,0:04:18.417 since the congestion charges were introduced in Stockholm, 0:04:18.417,0:04:22.406 and we basically have the same low traffic levels still. 0:04:22.406,0:04:24.677 But you see, there's an interesting gap here in the time series 0:04:24.677,0:04:26.140 in 2007. 0:04:26.140,0:04:28.529 Well, the thing is that, the congestion charges, 0:04:28.529,0:04:31.625 they were introduced first as a trial, so they were introduced 0:04:31.625,0:04:35.594 in January and then abolished again at the end of July, 0:04:35.594,0:04:38.188 followed by a referendum, and then they were reintroduced 0:04:38.188,0:04:42.388 again in 2007, which of course was a wonderful scientific opportunity. 0:04:42.388,0:04:46.525 I mean, this was a really fun experiment to start with, 0:04:46.525,0:04:48.306 and we actually got to do it twice. 0:04:48.306,0:04:50.415 And personally, I would like to do this every once a year or so, 0:04:50.415,0:04:51.903 but they won't let me do that. 0:04:51.903,0:04:54.088 But it was fun anyway. 0:04:54.088,0:04:57.473 So, we followed up. What happened? 0:04:57.473,0:05:01.339 This is the last day with the congestion charges, July 31, 0:05:01.339,0:05:03.117 and you see the same street but now it's summer, 0:05:03.117,0:05:04.861 and summer in Stockholm is a very nice 0:05:04.861,0:05:07.111 and light time of the year, 0:05:07.111,0:05:09.954 and the first day without the congestion charges 0:05:09.954,0:05:11.321 looked like this. 0:05:11.321,0:05:13.984 All the cars were back again, and you even have to admire 0:05:13.984,0:05:16.894 the car drivers. They adapt so extremely quickly. 0:05:16.894,0:05:19.141 The first day they all came back. 0:05:19.141,0:05:24.491 And this effect hanged on. So 2007 figures looked like this. 0:05:24.491,0:05:26.822 Now these traffic figures are really exciting 0:05:26.822,0:05:29.473 and a little bit surprising and very useful to know, 0:05:29.473,0:05:32.232 but I would say that the most surprising slide here 0:05:32.232,0:05:36.262 I'm going to show you today is not this one. It's this one. 0:05:36.262,0:05:39.593 This shows public support for congestion pricing of Stockholm, 0:05:39.593,0:05:42.262 and you see that when congestion pricing were introduced 0:05:42.262,0:05:46.579 in the beginning of Spring 2006, people were fiercely against it. 0:05:46.579,0:05:49.607 Seventy percent of the population didn't want this. 0:05:49.607,0:05:51.255 But what happened when the congestion charges 0:05:51.255,0:05:54.716 were there is not what you would expect, that people hated it more and more. 0:05:54.716,0:05:57.869 No, on the contrary, they changed, up to a point 0:05:57.869,0:06:01.570 where we now have 70 percent support for keeping the charges, 0:06:01.570,0:06:03.411 meaning that -- I mean, let me repeat that: 0:06:03.411,0:06:06.218 70 percent of the population in Stockholm 0:06:06.218,0:06:10.211 want to keep a price for something that used to be free. 0:06:10.211,0:06:13.837 Okay. So why can that be? Why is that? 0:06:13.837,0:06:16.837 Well, think about it this way. Who changed? 0:06:16.837,0:06:19.463 I mean, the 20 percent of the car drivers that disappeared, 0:06:19.463,0:06:21.408 surely they must be discontent in a way. 0:06:21.408,0:06:23.742 And where did they go? If we can understand this, 0:06:23.742,0:06:27.872 then maybe we can figure out how people can be so happy with this. 0:06:27.872,0:06:30.274 Well, so we did this huge interview survey 0:06:30.274,0:06:32.109 with lots of travel services, and tried to figure out 0:06:32.109,0:06:33.864 who changed, and where did they go? 0:06:33.864,0:06:38.278 And it turned out that they don't know themselves. (Laughter) 0:06:38.278,0:06:43.126 For some reason, the car drivers are -- 0:06:43.126,0:06:46.622 they are confident they actually drive the same way that they used to do. 0:06:46.622,0:06:48.878 And why is that? It's because that travel patterns 0:06:48.878,0:06:51.277 are much less stable than you might think. 0:06:51.277,0:06:54.108 Each day, people make new decisions, and people change 0:06:54.108,0:06:56.533 and the world changes around them, and each day 0:06:56.533,0:06:59.786 all of these decisions are sort of nudged ever so slightly 0:06:59.786,0:07:01.753 away from rush hour car driving 0:07:01.753,0:07:04.337 in a way that people don't even notice. 0:07:04.337,0:07:06.382 They're not even aware of this themselves. 0:07:06.382,0:07:09.183 And the other question, who changed their mind? 0:07:09.183,0:07:11.149 Who changed their opinion, and why? 0:07:11.149,0:07:13.675 So we did another interview survey, tried to figure out 0:07:13.675,0:07:18.051 why people changed their mind, and what type of group changed their minds? 0:07:18.051,0:07:20.944 And after analyzing the answers, it turned out that 0:07:20.944,0:07:24.829 more than half of them believe that they haven't changed their minds. 0:07:24.829,0:07:27.116 They're actually confident that they have 0:07:27.116,0:07:29.805 liked congestion pricing all along. 0:07:29.805,0:07:31.524 Which means that we are now in a position 0:07:31.524,0:07:34.517 where we have reduced traffic across this toll cordon 0:07:34.517,0:07:37.728 with 20 percent, and reduced congestion by enormous numbers, 0:07:37.728,0:07:41.275 and people aren't even aware that they have changed, 0:07:41.275,0:07:45.186 and they honestly believe that they have liked this all along. 0:07:45.186,0:07:48.660 This is the power of nudges when trying to solve 0:07:48.660,0:07:51.292 complex social problems, and when you do that, 0:07:51.292,0:07:54.922 you shouldn't try to tell people how to adapt. 0:07:54.922,0:07:57.109 You should just nudge them in the right direction. 0:07:57.109,0:07:58.831 And if you do it right, 0:07:58.831,0:08:00.883 people will actually embrace the change, 0:08:00.883,0:08:03.945 and if you do it right, people will actually even like it. 0:08:03.945,0:08:07.270 Thank you. (Applause)