The billions that Nairobians waste in traffic jams

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

23 August 2009

How much does it cost when vehicles are kept in a traffic jam? That sounds like an incalculable problem but we can attempt it by making a few reasonable assumptions. First we have to identify the major costs that are incurred when cars are stationary in a gridlock. Off the top of my head, I can think of the wasted fuel while the engines are idling (but not going anywhere) and the time lost by the people in the vehicles.

Next we need to estimate the number of vehicles that are held up traffic jams on our roads, especially in Nairobi. To do that, I will start with road that I am very familiar with and then extending the results to the whole city.

The Uhuru Highway / Mombasa Road has some of the most notorious jams in Nairobi and I use this stretch almost every day. The traffic tailback can run from the Westlands roundabout all the way to the Zain Headquarters on Mombasa Road. This is a distance of about 10km.

Now of course the jam will not be on both carriageways, but there will be stationary vehicles on at least one side on every point along the whole stretch – especially in the mornings and evenings.

If we allow an average of five metres for each vehicle, we find that there will be about 2,000 stationary cars on each lane. But the road has three lanes on each carriageway; therefore, there will be about 6,000 cars on this stretch during a jam.

The peak hours are usually from 7 to 9 o’clock in the morning and from 5 to 7 in the evening. This makes a total of four hours. Now, before we even go farther, imagine holding 6,000 cars stationary for four hours every day!

No: I am not suggesting that driving on this stretch will take you two hours – though that does happen on some days. What I mean is that when the cars on one side start moving, those on the other one stop. Therefore, at any one moment, there will be a stationary vehicle on every part of the road.

Now, the engines of these vehicles will be running while waiting for the jam to clear. The average car consumes about 5 litres of petrol per hour while idling. Thus in four hours it will consume about 20L. The 6,000 vehicles will therefore waste about 120,000L of fuel every working day.

In a year, there are 250 working days; therefore, the annual fuel wastage is about 30 million litres. Yes; 30,000,000L! At today’s prices of about Sh80 per litre, the total cost is Sh2.4 billion…on one road only.

I estimate that Nairobi has at least 200km of roads that are affected by traffic jams (one day I will actually measure them on a map). But not all of them are three lane highways: some have two and others have only one.

Thus to account for this, I will assume that the 200km is equivalent to 100km of three-lane dual carriageways. Since every 10km is wasting Sh2.4 billion, it is easy to see that the 100km wastes Sh24 billion on fuel alone.

How about the value of the time wasted? Well; digest the above calculation first and, next week, we shall look at the second part.