The interstate highways were partially designed to be able to evacuate large cities in the case of a nuclear attack. As anyone who has traveled on such roads during rush hour can well attest, their ability to do so is quite lacking.
In modern times, the one major natural disaster we have that can be reasonably well predicted ahead of time to afford lengthy evacuation times is a major hurricane. We discovered during Hurricane Ike, however, that even a large city with ample lead time and comprehensive evacuation planning (including lane reversal plans to maximize egress capacity) cannot be adequately evacuated for a hurricane.
What can be gleaned from the more mundane task of trying to move commuters into and out of cities is that, if your goal is to move people, then the first thing you should do is take them out of their cars. A highway lane has a fixed capacity of about 2,000 vehicles per hour, independent of if those vehicles are carrying 1 person or 100 people.
Has anyone evacuated a city by rail (and bus?) in a reasonable time?
It wouldn't be necessary in Europe, since there aren't any expected disasters where evacuation is useful, but for comparison anyway, about 1.2 million people arrive in central London by metro or regional rail every morning.
So long as people don't mind where they end up — which is a huge and unworkable assumption — you could possibly evacuate central London by rail alone. Possibly. For a careful definition of "central".
Although the rail system has a very high capacity when everything works smoothly, it doesn't perform so well if there is disruption. Perhaps that is mitigated somewhat if you don't particularly care where the trains end up.
But the road network would probably work a lot better if there wasn't anyone trying to collect their children and spouse, then their elderly relative, before leaving.
Does evacuation by rail happen anywhere in Asia? Japan?
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But now I see we were only discussing evacuating 100,000 people. That's a routine event after a football match at a large stadium in Europe. Wembley Stadium in London can hold 105,000 for a rock concert (or 90,000 for football), and the vast majority of people leave by metro or regional train within about an hour of the end of the concert.
Again though, that's using a transport system suitable for a major capital city to evacuate a town's worth of people. A town alone wouldn't invest in this much capacity.
This is actually a well oiled machine at Twickenham, home of rugby, where the capacity crowd is nearer 80000.
There is just the one station and, come end of the match, there are no additional trains put on. People just use the regular commuter trains that are on the regular routes up to Waterloo station in central London. Even when there is a match you can get the train as a regular traveller although getting a seat is unlikely.
Only a modest amount of staff are needed at Twickenham station for crowd control. There is practically no parking at Twickenham so that crowd really does have to get the train or park far away from the stadium in a residential street.
It takes people a while to diffuse down to the station so there are packed trains for a good couple of hours.
The same trains also serve Ascot where the horses race. So you can have a train half full of people in rugby shirts and half filled with 'silly hats', as per the fashion at Ascot.
Not only that but the same trains can carry thousands of more people heading up to London for the Notting Hill Carnival (again no parking, drinking likely).
To further stretch the capacity of this small commuter line, you can also have another younger crowd on the same trains and at the same time heading to Reading, which is at the other end of the line, for a rock festival.
This can all happen with 'weekend engineering work' on the line, delays being merely typical for South West Trains, i.e. ten minutes late with the odd cancellation.
There can be delays due to drunken people deciding to press the alarms and opening the doors in between stations, or other such silly behaviour.
Despite all of this trains come through, people get to where they are going and everything is remarkably orderly. The mood on these trains is more like the atmosphere on a lift - you know, nobody talks, everyone behaves and there is no confrontation. It is really quite remarkable and efficient.
Come Monday morning and the commute to work, now that is when the trains on this small branch line get seriously packed. Being able to move your rib cage for the purposes of breathing is not so easy at 7.30 a.m. on those trains that did such an excellent job of getting everyone to the rugby over the weekend.
Evacuees need to carry their infants, pets, and enough luggage to live for a few days... there’s nowhere near crush-load commute capacity. There is no point to a little town in the woods if it’s going to be urban enough for transit coverage. It really looks like humans just shouldn’t live in places like this.
Towns obliterated by fires just don't happen often enough that we need to make forests "no-go" areas. Even if one town per year were completely destroyed it wouldn't be sufficient justification because there are many such towns and the probability of a specific one being destroyed is still a once in a century event.
Why are cities not planned such that evacuation routes are already commonly used routes in the morning peak? If you plan city that way, all roads will saturate equally instead of all traffic stuffing on highways and arterials, in non-evacuation scenarios.
EDIT: descendant merged
In normal use, the peak travel pattern is essentially a unidirectional peak into the city in the morning and the opposite direction in the afternoon. That usually calls for a load that can handle the peak unidirectional traffic with the other direction being fairly empty, as managing the reversibility of lanes is difficult. (That said, the highway near to me right now does have three lanes of HOV that reverse direction, although that is one of the longest stretches in the entire world of such reversibility that is regularly exercised).
However, there is an important difference between the regular commute and evacuation in terms of traffic patterns. In the regular commute, the flow generally extends only between the suburbs and the city core; in an evacuation, you generally need to go a much further distance, well beyond the furthest suburbs. As a result, you're looking at carrying evacuation routes on roads that are only meant to handle at worst summer vacation inter-city travel, so you see 12 lanes of traffic have to scrunch into 2 lanes of traffic.
This. People would rather have "rush hour" be from 3-8pm rather than pay for enough spare capacity that peak demand only saturates the system from 5-6.
If a four lane highway is saturated for 3hr you'd need twelve lanes to cut that time to 1hr. That's a lot of money.
They're completely different scenarios. Commuting is usually one-directional towards the center of the city and business areas with the working population.
Evacuation is outward to completely leave the city, and includes everyone and their luggage, while being squeezed through suburban areas to just a few interstate highways.
Yes, but planning to make sure commuting and evacuation patterns identical would make the city sufficiently distributed. You would obliterate the CBD problem which causes rushed congestion in roadways. You would just need to go further to evacuate such a city.
In modern times, the one major natural disaster we have that can be reasonably well predicted ahead of time to afford lengthy evacuation times is a major hurricane. We discovered during Hurricane Ike, however, that even a large city with ample lead time and comprehensive evacuation planning (including lane reversal plans to maximize egress capacity) cannot be adequately evacuated for a hurricane.
What can be gleaned from the more mundane task of trying to move commuters into and out of cities is that, if your goal is to move people, then the first thing you should do is take them out of their cars. A highway lane has a fixed capacity of about 2,000 vehicles per hour, independent of if those vehicles are carrying 1 person or 100 people.