Is investing in infrastructure enough?
In many developing cities, travel by car, motorbike, bicycle or by foot are the main means of transport in a city. Meeting growing demand for these private means of transport requires investing in building and maintaining infrastructure for private transport. The density of paved roads, for example, in countries in sub-Saharan Africa is less than a quarter of that in other low-income countries1. Without addressing these deficits, access to opportunities across a city are limited. Initial results from a study of 154 cities in India suggest that around 70% of differences in car speeds in a city are the result not of traffic, but of the extent and organisation of road infrastructure2.
Initial results from a study of 154 cities in India suggest that around 70% of differences in car speeds in a city are the result not of traffic, but of the extent and organisation of road infrastructure.
Infrastructure for non-motorised forms of transport in particular offer low-emission, low cost access across shorter distances and in dense central areas of cities can offer the quickest form of travel. Non-motorised infrastructure also comes at relatively low costs; estimates suggest that a pedestrian walkway that can accommodate 4,500 people/hour/direction costs approximately USD$100,000/kilometer. This is up to 50 times less costly than an urban road that can carry only 800 people per hour per direction3.
However, investing in infrastructure for private transport is not going to be sufficient to meet growing demand:
- Private cars have low carrying capacity, and so without investing in higher capacity transport options, roads are less able to transport high volumes of passengers.
- Investments in roads take time and come at a significant cost. The average cost of constructing a two-lane concrete highway across developing countries is approximately $1.5 million per kilometre4.
- Evidence from US cities suggests that there is a fundamental law of highway traffic: expanding roads, although allowing for greater ease and access of transport for many citizens, will not solve a city’s congestion problem. This is because as incomes and populations rise, vehicle use will rise to fill these new roads5. In Accra, for example, despite relatively good roads, traffic congestion continues to rise as around 2 million commuters travel to the downtown central business district each day. This problem is only likely to grow as the population of Greater Accra is predicted to double by 2035, along with private vehicle use.