Expressway gaps show Nairobi jams will not end soon


The ongoing construction of the Nairobi Expressway along Mombasa road. FILE PHOTO | NMG

In 1865, William Stanley Jevons, a British economist wrote an influential essay titled The Coal Question. Today, his insights are interesting to me not as they relate to coal production, but rather as they relate to me sitting in the legendary traffic on Mombasa Road.

According to Jevons, an increase in the efficiency of coal production would stimulate increased demand for coal. In wisdom, Jevons believed that more efficient coal production would translate to lower prices. Interestingly, however, Economics 101 is of a different opinion that states that lower prices lead to more consumption — perhaps, in this case, creating so much more demand.

It is actually possible to argue that increased production of coal will result in heightened demand as populations respond to the increased ‘availability’.

These same insights about coal are applicable to mass transportation systems — particularly expressways.

The Nairobi Expressway was touted as a solution aimed at managing traffic congestion in the city, needless to say, the problem is in actual sense rise in driving demand as a result of increased capacity.

This is a favourite of economists because people who value time more will pay a premium to avoid the costs of congestion.

Consequently, the scarce resource — road space — will be rationed according to its relative value to consumers. Of course, it is not only the value of time that matters in the decision; the ability to pay as well.

The introduction of the elevated highway without the highest of doubts will only allow ‘rich’ people to drive fast while reducing the capacity on the freeway for everyone else. And that raises issues of equity for infrastructure built with taxes.

The other problem with elevated highways is that there is an alternative to drive in the now more congested free surface streets. With navigation apps, drivers can take the nearest off-ramp and motor through residential neighbourhoods, otherwise known as overlapping.

When they do that, they expose residents to the congestion, noise and pollution that the elevated highways were originally built to eliminate.

Moreover, research indicates that when fed-up expressway commuters start taking app-directed shortcuts through residential areas, the local roads quickly become clogged, hampering residents’ ability to make short trips or run errands. These residents pay a cost in congestion, safety and pollution.

Evidently, expressways don’t seem to be a complete answer either. Recognising this, other cities followed the example of Julius Caesar, who in the first century BC Rome banned chariots from the city centre during the day, except for two hours in the morning and two hours in the late afternoon.

All we can do for now is stay ahead of the game. Provide incentives for people to use the least-used modes of transportation and plan for the increases in population that will invariably happen to cities that are attractive to people from far-flung lands.

What will be required is to engage transportation planning with housing planning in a way that recognises the close tie between the cost of congestion and the price of housing.