Nairobi has a population of 3.5 million and a density of 4,850 people/Km2. This is low when compared to Lagos with 11 million people (18,500p/Km2) or Bogota with 7 million (13,500p/Km2). Estimates show that by 2025 there will be about 5.8 million people living in the city. Nairobi has to plan towards sustaining such a population.
Mobility will be as crucial for this 5.8 million as it is today. Perennial traffic jams have led to a shift in peak hours over the last ten years and Nairobi is ranked by some as the 4th most congested city in the world.
Nairobi’s structure, like in Hoyts Sector theory and Burgess’ concentric model, has a strong Central Business District (CBD) where most stores, government offices and businesses are located. It also has a mix of both concentric circles and growing sectors moving away from the CBD with an industrial zone and various residential areas. The City also sprawls along the major highways that eventually merge at the CBD. Thus, traffic congestion is at its worst on the roads leading to the CBD or extended CBD area.
Attempts at reducing this congestion via government and donor funded road construction have not helped as vehicle numbers increase and points of origin and destination remain the same. The NUIPLAN proposes a Bus Rapid Transit (BRT) similar to that in Bogota and Ahmadabad and there is a recent drive towards the construction of a commuter Rail system. BRT secluded bus ways can reduce the attraction of personal car use while commuter rails reduce road dependency.
However, these are not ultimate solutions. BRTs function well developing countries on routes carrying up to 30,000 per hour after which Rail options can be considered. (Bogota’s overstretched BRT serves as a good example). Rail systems on the other hand, require high ridership’s and need subsidies for sustenance. Some cities, like Paris, sustain them through a ‘commuter tax’.
But what happens beyond mass transit?
The vision of Nairobi 50 or 100 years from now will be based on the decisions made today. Do we want a city where people have access to a variety of means of mobility, or one with 4 million cars trying to move around (estimated ratio of 0.7 cars per person)? Will the CBD and environs remain as the heart of business and human activity that everyone has to access?
This brings into focus the importance of land use management. The city needs to develop such that the points of origin and destination need not be far apart. Where the CBD is not the primary destination in the morning and everyone’s exit point during peak evening hours. Can business parks, quality schools and residential areas be located near each other reducing travel distances? Can there be more emphasis on densification along proposed mass transit lines while making maximum use of land on, above and below the ground?
Mixed Use Development can reduce the need for highways, long travel distances and curtail the sprawling city.
Long term land use management in the city is a key means of reducing congestion. This goes beyond engineering solutions like road construction and mobility infrastructure. Re-planning the city in a manner that brings peoples’ points of origin and destination closer thus reducing the need for long travel times will go a long way towards ‘decongesting’ a city.
How well can land use management be used to decongest the city roads based on the current zones? What other long term considerations can be used to develop a more sustainable city?