How to cure traffic jams without controlling the flow

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

09 August 2020

One of the great mysteries of Kenya is that we spend a lot of money installing traffic control signals and then deploy police officers at the signalised junctions to control the flow. In 2006, I was invited to help in programming a traffic control system at one of the roundabouts in Nairobi.

The cost of the equipment and installation for this one roundabout was about Sh5 million at the time. If we factor inflation of about 5 per cent per year, then today’s price should be about Sh10 million. Why does the City County spend sh10 million on something that it does not make use of?

Now, there is one simple arithmetic that any officer directing traffic at a roundabout should always keep in mind: the duration you open the flow adds up to the duration you stop it. For example, at a roundabout with 4 inlets, if each is allowed to go through for 2 minutes, the each will have to be stopped for 6 minutes.

Stopping traffic flow for 6 minutes creates a queue of at least 200 cars stretching for one kilometre! And untold havoc at the roads feeding traffic into the main street.

But there is hope. I drove from industrial area to the University of Nairobi recently. Before starting off, I asked Google Maps for route suggestion and it showed that the quickest was through Dunga Rd to Bunyala Rd and then along Uhuru Highway.

The section from Bunyala junction to University Way was marked red indicating heavy traffic. Still; I used the suggested route and, on reaching Uhuru Highway, I found that it was clear. For once, Dr. Google was wrong!

However, as I drove along, I noticed that the good Dr. Google was continuously turning this section from red to blue (smooth flow) in real time. This gave me an idea: what if all drivers in the city used Google Maps to plan their routes?

The system would send everyone along the quickest routes and, within a matter of a few minutes, all the traffic jams would disappear! No traffic lights need; no traffic police needed.

Hey, fellow Nairobians: lets do this!