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Less is more: BRT and metro avoid expansion of road infrastructure
Road expansion in Bangalore

In Bangalore, India, road expansion was required due to the absence of high quality public transport. Other cities might avoid this fate by including a consideration of the “supply increase” concept in the baseline assessment of transport projects. Photo by Sudhir Gota.

In the realm of conducting transport economic and environmental assessments, the option of “doing nothing,” or “no project/investment,” is considered as the baseline for all projects. A baseline is a reference pathway against which the impact of a project is measured.  Potential benefits of a project are always compared to the “do nothing” option – scenarios of inaction – before a decision is made. However, the notion that it’s possible to “do nothing” is a myth: the demand for transport is so strong in many countries that inaction entails the business-as-usual of building more roads. Considering this reality in baseline assessments could be a game-changer for sustainable transport projects, like Bus Rapid Transit (BRT) and metro, that would allow their benefits to shine even brighter in assessments.

Doing nothing: An outdated baseline for sustainable transport projects

No city has managed to sustain “doing nothing” as the cornerstone of its policy making. We can examine the “do nothing” concept in simple terms: if the total ridership of a proposed project – BRT or metro, for example – is 10 million over 20 years, the baseline would be the same amount of trips traveling in different modes of transport without the project. However, it’s illogical to assume that the same amount of existing roads would accommodate such a drastic increase in traffic volume without expanding or adding a suitable alternative. Indeed, the normal course of action for developing cities is to increase road supply to combat congestion. Thus, in practice the “do nothing scenario” actually implies “doing something” – increasing supply to sustain projected traffic. Incorporating this “supply increase” concept into the baseline has the potential to radically alter the project evaluation approach of sustainable urban transport options.

Impact of BRT and metro projects

In order to investigate the implications of road supply increase without implementing a suitable alternative, let us consider some public transport BRT projects: Ahmedabad, Cebu, Guangzhou, Pimpri, and metro projects: Chennai, Bangalore, Ho Chi Minh and Metro Manila.

All of these systems were justified based on mode shift – by shifting the projected vehicular trips, including those made on buses, to more efficient modes of public transport. The vehicle travel they prevented ranged from 2 to 25 billion over 20 years. All these projects assumed those trips would occur irrespective of a BRT or metro implementation in the baseline. However, it’s impossible for the baseline to accommodate billions of vehicle kilometer travel increase without also proportionally increasing road supply. This necessary increase in infrastructure is a cost of not implementing BRT or metro projects, which needs to be quantified.

Avoided infrastructure by BRT and metro implementation

In order to make the most conservative calculation of avoided infrastructure, I have considered Singapore’s approach to road expansion. Singapore does not follow the traditional approach of increasing road space as congestion increases. From 1991 to 2012, the vehicle kilometer travel increased by 2.2% while road supply (lane kilometers) only increased by 1%. Singapore has limited land supply, so road widening is only carried out when all other options fail. Considering Singapore’s experience with road supply increase, and translating its ratio on projected vehicle travel into a project baseline for any BRT or metro project, allows a conservative computation of infrastructure increase in the absence of new public transport project.

Avoided infrastructure in lane kilometers

Avoided infrastructure in lane kilometers for BRT and metro projects in selected cities. Calculations and graph by Sudhir Gota.

Both BRT and metro systems save substantial potential investment in expanding roadways. Avoided infrastructure due to construction of BRT and metro can range from 100 to 1,000 lane kilometers for different projects, based on the intensity of avoided travel.

The average avoided road space for a BRT and metro are two and three square meters per ridership, respectively. This is a conservative calculation modeled on Singapore’s experience, which doesn’t consider the impacts of road widening, such as parking space, increased traffic, and more. In terms of costs, BRT projects costs five to twelve times less than costs due to road expansion. With the addition of this single parameter to the baseline, cost effective projects would become economically viable, and benefits like emission savings, fewer road accidents, and positive health impacts due to less pollution would get more attention from policymakers.

Avoided road space versus BRT costs

Avoided road space versus BRT costs. Graph by Sudhir Gota.

The potential savings in terms of avoided infrastructure from implementing sustainable transport projects like BRT or metro systems are vast. Including a measurement of these savings in decision making processes has the potential to radically alter our perception of worthwhile urban transport projects. In light of growing requirements for transport financing, including this parameter would give more cost effective, sustainable solutions a boost.

Sudhir Gota is a 2013 Lee Schipper Memorial Scholarship for Sustainable Transport and Energy Efficiency recipient. For more of Sudhir’s work, see his recent posts on TheCityFix regarding predicting motorization in China and India’s diesel consumption.