Traffic Signal Optimization

 

Have you ever gone somewhere and it seemed like you hit every single red light between your house and your destination?  You could swear the traffic gods are against you because it doesn’t seem to matter what speed you travel at, you still get stopped?  I have felt that way quite often.  In terms of mathematics, it is referred to as traffic light optimization.  

Traffic light optimization is defined as the process of optimizing the timing of traffic lights to as to make it so people do not have to idle too long and cars do not have to speed to make it to the next traffic light which causes a decrease in the release of carbon dioxide and cars consume less fuel.  It is also used to help increase overall traffic flow.  

We know that traffic modeling looks at unidirectional flow where the density of cars is based only on a single spatial dimension.  Recently, certain traffic models have begun looking at intersections because they form a large part of the whole system.  The models do one of two things.  They either look at minimizing travel time or maximize the flow of traffic.

We know that traffic models look at traffic as a fluid flowing including traffic jams and traffic lights are used as a tool to redirect traffic so as to mitigate issues even on roads that have a high traffic flow.  So mathematicians look at the ratio of traffic volume to capacity among other things. Another thing that traffic light optimization needs to include  how long it takes for people to cross any street at a traffic light.

There are two types of traffic signal optimization.  The first is time-of-day scheduling where traffic signals are set to have exactly the same cycle length which can change based on the demands of traffic throughout the day.  This schedule is the same day after day.  This schedule is good for roads with over 400 cars per hour, downtown areas, areas with bicycles and buses, and special events.

The second is set to respond to traffic. The signal has several pre-programmed timing plans which are implemented based on the demands of the traffic. This works best in situations where there is only one traffic light here and there.

When looking at traffic signal optimization, people have to consider how long the whole light cycle is for red, yellow, and green, the time the amount of time it takes for traffic to get from one light to the next based on the posted speed, 

In addition, traffic signal optimization is not done just once but is redone multiple times to account for population growth in the form of new developments, and increased traffic, to cut down on delays or stops so drivers are less frustrated, to improve traffic flow so vehicles use less fuel and produce less emissions, and finally to allow current infrastructures to carry higher numbers of vehicles thus delaying the cost of adding infrastructures.  If utilized properly, traffic signal optimization can produce a benefit to cost ratio of 40 to 1 which is quite good.  

This is the basics of traffic signal optimization and why it is important.  There is a lot of math involved in setting everything up.  Let me know what you think, I’d love to hear.  Have a great day.