No one likes traffic jams. They waste time, waste fuel and make everything miserable. But what makes you tick is the fact that when you finally clear the congested traffic patch on the road, there is nothing in sight that could have particularly caused a jam. There is not road working going on, no broken down vehicle or a signal to disrupt the traffic. Yet you are stuck in the traffic and crawling and continuously stopping, putting your car in first, driving, and then stopping again.
Last year in December, Pakistan Sustainable Transport Project (PAKSTRAN) held a workshop in collaboration with UNDP named “sustainable urban transport policy and transport/traffic management issues” about the menace of increasing traffic in the country. One of the reports presented at the event remarked that at least PKR 400 billion of fuel burns annually due to the traffic congestion across the Karachi city. The report blamed several factors for the congestion including deteriorating infrastructure, unnecessary traffic signals, and illegal encroachments.
But then there is a human factor as well. Human behavior of how the driver is driving his or her car disrupts everything. One minor disruption in the traffic flow, like forgetting to keep the foot in the race pedal while changing the radio stations will cause all the traffic behind you slow down as well. And then you will speed up to catch the traffic in front and so will the others behind you to catch up with you. And so the cycle of disruption has started. This is what is called the concertina effect. It’s also known as an accordion effect.
Basically one of the drivers breaks the flow of the traffic. And it causes the disruption in the flow of the vehicles following. In such traffic you accelerate, then you brake because the vehicles in front are braking, and so are the cars in front of them, and so on and so forth, until you pass the origin of the disruption. But the interesting thing about this phenomenon is that it travels backwards. This invisible traffic jam keeps tracing back until there is a break in the traffic flow let the void widen.
There is this interesting web game that I came across yesterday. Basically, the goal is to keep the traffic in a flow. The moment you slow down your car, the cars behind will start to brake and slow down as well. So you have effectively broken the flow of traffic. And hence the birth of invisible traffic jam.