We cannot build our way out of traffic congestion

Nairobi like every other growing metropolis worldwide faces a myriad of challenges that come with urbanisation. Traffic congestion has been the most common challenge. Rapid population increase and drastic changes in land use patterns, from previous agricultural to residential, has equally created sprawling human settlements, resulting in a demand for increasing road capacity.

It is due to this demand that 10 years ago, a project for constructing an expanded Thika road started. The project responded to the need to increase road capacity and as such supply more roads to suit the established demand. This saw the expansion of Nairobi - Thika Road, from a four lane highway to eight, and in some sections 12 lanes, at a cost of Sh31 billion.

The project was touted as one that would reduce peak hour traffic congestion, reduce travel time and enhance efficient mobility. Seven years after the opening of the road, the objectives and expectation for its expansion remains to be seen, in actual sense, there is still ‘demand’ for more lanes to ease its traffic. 

While it is true that the expansion of the road enabled it to carry more cars per hour and thus increased traffic volume, the intent to reduce congestion and ease movement has not been met. It brings forth a trait of the cars behaving more like gas rather than liquids — gas expands to fill the available space. 

Today, more cars use the road, resulting in longer journey speeds and substantial congestion as evidenced by long queuing especially during peak hours.  

The environmental impact of the road has been dire. Particularly, there has been an increase in emission and degraded air quality. Economically, there is obviously loss of time and money, congestion has also led to hiking of fares during peak hours to compensate for time spent in traffic.

It is, therefore, not in doubt that building our way out of congestion doesn’t seem to work, as such moves have become counter-intuitive. Thika Road has not become any better, improved road capacity has led to increased traffic jams, not any better from the four lanes that it previously was. Traffic congestion along the major spine road is as a result of increase in the number of vehicles brought about by an increase in population and settlements around this stretch.

The phenomenon on Thika Road is best explained by the Braes Paradox and also holds true the fundamental law of road congestion. Braes paradox stipulates that an increase in one or more roads in a road network might end up hampering overall traffic flow through it and removing parts of it may improve traffic flow. Traffic jams and road congestion, not only impact the individual time spent in traffic but have implications on the total man hours lost and thus negatively affect the Gross Domestic Product.

In a developing country like ours, the impact of land use patterns on transport networks cannot be underestimated. Sparse and sprawling developments are car-centric and circumvent densities required for investment in public transport within the neighbourhoods.

They make it difficult for other transport options, but use of private cars to aide in accessing the main arteries. Secondly, lack of efficient and reliable public transport pushes a section of commuters to use private cars to enhance their daily mobility. It is worthy noting that matatus are not public.

Mass Rapid Transit

To address the challenge of traffic congestion, we must put the first things first. We need to address the need for provision of efficient and reliable public transport. We remember with nostalgia the days Kenya Bus Service operated in Nairobi, Kiambu, Kajiado and Machakos routes.

Secondly, peri urban land use patterns must be planned and regulated. Low densities deny opportunities for investment in public transport systems. Densely populated neighbourhoods and compact urban development along transport corridors will provide requisite densities that will meet thresholds for investment in public transport options such as bus rapid transit, mass rapid transit and light rail transport.

We should apply multi-pronged approach in addressing traffic congestion. Re-introduction of public transport is necessary. This will ensure transport of people rather than facilitating movement of vehicles. Introduction of priority lanes for public service vehicles might ultimately convince and shift commuters from their private cars.

To address concerns of the neighbourhoods located far off the main arteries, park and ride facilities that are safe and inexpensive may also ease off the pressure from the main artery. In addition, use of personal vehicles should be discouraged through the introduction of high parking fees.

Ms Kirui is a physical planner