Given the increasing traffic congestion in cities, this is indeed a timely topic that affects citizens and businesses and raises many relevant issues, some of which are not self-evident and in fact, it may seem contra-intuitive.
In a study conducted by UN Habitat, an analysis of the road pattern of Nairobi based on satellite images shows first that Nairobi, has currently 23 different street patterns in its urbanised areas (see satellite image).
One reason for traffic-congestion is that streets are not fully connected to its vicinities. A second finding revealed by this analysis is the amount of land allocated to streets.
As an example, in the central part of Nairobi, the space allocated to the streets amounts to approximately 12 per cent of the land area, while a functioning traffic system in a modern capital requires around 30 per cent of land to be allocated the street.
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These two big findings lie at the heart of the traffic jam problem in Nairobi ? too many street patterns and too few streets that are adequately connected.
Against this basic analysis, what remains critical is the kind of interventions that will provide the most efficient results, bearing in mind the lack of financial resources available to undertake big transformations.
Therefore for UN-Habitat, the UN agency mandated to work on sustainable urban development, the first priority is the proper connectivity of the different street patterns of the city. Increasing the linkages between the different street patterns and the neighbourhoods might sound irrelevant in the analysis of the problem of congestion. However, an in- depth scientific approach based on traffic flow analysis can easily demonstrate that the lack of connectivity between neighbourhoods is the first source of traffic congestion. A much smaller investment than the amount lost due to traffic congestion in Nairobi (estimated at Sh37 million) if spent on better street connectivity would solve the congestion problem.
Inextricably linked to the main problem of lack of connectivity is the need to increase the percentage of space dedicated to streets - moving from the current 12 per cent to at least 25 to 30 per cent of space dedicated the streets, resulting in a positive transformatie current mobility pattern.
When trying to move in this direction, an important factor is to make sure that the required legal instruments to properly implement the urban plan are in place. It’s only through a comprehensive urban plan and adequate urban legislation that we can achieve a significant improvement in the street fabric needed to ensure the smooth flow of traffic in Nairobi.
A third and extremely relevant aspect is related to the costs of increasing the space dedicated to streets. This can be relatively high for which, a proper model of investments is required.
In many cities in Africa, acquiring additional public space has been tough. But the common problem of expropriation is that it requires a lot of money which is not available and also often leads to time consuming litigations.
The solution that many countries have articulated to address this problem of public acquisition of land for street pattern is through Land Readjustment (LR). Land Readjustment is a legal instrument by which the urban plan establishes a clear definition of the street pattern, and the land to implement the street pattern foreseen in the plan is given to the public authority, in exchange of enhanced buildability rights to owners of the plots.
Since a good street pattern increases the value of the buildings in the vicinity, it is a win-win situation for the owners of the land, the urban developers and the local authority. The contribution of land for street pattern is financially compensated through means of development rights.
Then the means by which the public land is acquired by the public sector is not monetary but in terms of development or buildability rights. This is the methodology that has been established around the world to address the problem of the scarcity of space for a functional street pattern.
This can be implemented through laws that allow the introduction of Land Readjustment in the country or the city of Nairobi.
Therefore there are different options including national legislation or metropolitan legislation, or even local legislation that can address this question. Failure to address urban planning fundamentals for the problem of mobility can induce skewed policies which may superficially seem effective, for instance introducing new transport systems, like trams or similar.
But these do not solve the basic problem and can indeed worsen congestion. Therefore it is important to understand the need to address the urban planning fundamentals that underpin a good mobility system.
In that sense, UN Habitat recommends due attention be given to a comprehensive urban planning to avoid unnecessary or even counter-productive expenditures that will not improve traffic flow. Nairobi has many assets, including its international connectivity, unique climate and natural conditions, Therefore, Nairobi can become an even more vibrant hub in the region with good road network.
—The writer is Coordinator of Urban Basic Services at UN-Habitat