Reports from up and down the coast of Japan have commented, almost as an aside observation, that the roads out of towns were essentially gridlocked as the tsunami approached. Now I’d guess that a lot of people will conclude that roads came to a stand still because somewhere a building had blocked the road, or a car had broken down at the head of the traffic or because of some other external factor. In other words, that the people trapped in their cars were unlucky; that they had given themselves the best of all chances to escape but had been foiled by circumstances beyond their control.
But that’s very far from the reality.
See, if you receive a tsunami warning, you might intuitively jump into your car reasoning that it’s your best chance of out running a 60km/h wall of water. And there’s only one flaw. In the situation of a town evacuation, the moment you jump into your car to escape you more or less guarantee that you will die.
While it may be the case that some roads become impassable due to physical barriers, it will make no difference to the efficacy of escape by car if there are no obstructions and no broken down vehicles blocking the roads. And even if the total volume of traffic doesn’t exceed the carrying capacity of the roads, traffic will come to a stand still and people in cars will be going nowhere as the wave hits.
A study was conducted on this phenomenum. Researchers were curious as to why motorways often came to a standstill even where there are no road works, bottlenecks or accidents. The study found that if the volume of traffic is heavy enough (ie, if the actions of the car in front elicits a response from the car to it’s rear…as like in a mass evacuation) and somebody travelling at 100km/hr applies their brakes for a split second, then that will unleash a momentum of deceleration travelling back through the column of traffic that will result in traffic coming to a dead stop.
And as we all know from sitting even just six or seven cars back from a green light, a time lag comes into play when we are looking at getting a stationary column of traffic moving again. Meantime, if somebody towards the front of the column accelerates a little too quickly and has to touch their brakes…
It’s pointless to speculate on the numbers of people who died unnecessarily because they put their faith in a car as being the fastest means of escape. Sure, some might have had enough time to get to safety by foot or bicycle. And for some there would have been no possible means of escape no matter what.
But it’s worth noting out that in the case of a reasonably sized population looking to get itself away from a tsunami, that a car offers no means of escape at all and instead becomes, quite literally a death trap.