Efficient Public Transport: Lessons from Cervero and Kenworthy

Public transport is the system of buses, metros, trams and commuter trains that moves most people in dense cities, and the infrastructure that most determines whether a city is sustainable, accessible and fair. A single bus rapid transit lane carries as many people in an hour as ten lanes of cars, with a fraction of the energy and space. Two researchers have spent decades studying what distinguishes the cities where public transport works: Robert Cervero of the University of California, Berkeley, and Jeff Kenworthy of Curtin University in Perth, co-author with Peter Newman of the international comparisons on automobile dependence.

Robert Cervero and the transit metropolis

Cervero, in The Transit Metropolis: A Global Inquiry (1998), studied twelve metropolitan regions, from Stockholm to Curitiba and from Tokyo to Ottawa, and concluded that the success of public transport depends on how well it fits urban form. There are adaptive cities that concentrate housing and jobs around stations, such as Copenhagen or Singapore, and adaptive transit systems that take the service to where people already live, such as Adelaide's flexible buses. Both strategies work when land use and transport are coordinated; they fail when a metro is built and the land around it is left to car parks.

Transit-oriented development and the three Ds

From that research came transit-oriented development, a model that concentrates density, mixed uses and walkable design within 500 to 800 metres of each station. Cervero and Kara Kockelman summed it up in 1997 as the three Ds, density, diversity and design, later joined by distance to transit and destination accessibility. When they are met, public transport use multiplies and car use falls. When they are not, the station is surrounded by empty land and the service runs at a loss.

Jeff Kenworthy and automobile dependence

Kenworthy and Newman compared transport energy use in dozens of cities in Cities and Automobile Dependence (1989) and Sustainability and Cities (1999). Low-density American cities burned up to ten times more fuel per resident than dense Asian ones, with European cities in between. The conclusion is that density and the quality of public transport explain car dependence far better than income or petrol prices. Kenworthy also argues that service quality, frequency, punctuality, commercial speed and legibility, matters as much as infrastructure.

Pillars of efficient public transport

Efficient public transport rests on four pillars. Coverage and frequency: stops within a ten-minute walk and services every few minutes, because waiting is the largest perceived cost. Universal accessibility: level boarding, lifts, clear information and affordable fares, with fare integration across modes. Safety: lighting, staff presence and visible design at stations and stops, which matter most to women and older people. Intermodality: bicycle parking, connection to the pedestrian network and coordinated timetables between bus and rail.

Sustainability adds fleet electrification and renewable energy, but the biggest emissions saving comes from shifting trips from the car to collective transport, not from changing the bus engine. That is why Cervero and Kenworthy insist that investment in public transport must go hand in hand with policies on the car: regulated parking, congestion charges, reserved lanes. Cities such as Zurich, Vienna and Bogotá show that a frequent, integrated system with priority on the street can carry more than half of all trips and make the city fairer for those who do not drive.