Optimizing urban bus transit network design can lead to greenhouse gas emissions reduction

Julia B. Griswold, Tal Sztainer, Jinwoo Lee, Samer Madanat, Arpad Horvath

Research output: Contribution to journalArticlepeer-review


The high contribution of greenhouse gas (GHG) emissions by the transportation sector calls for the development of emission reduction efforts. In this paper, we examine how efficient bus transit networks can contribute to these reduction measures. Utilizing continuum approximation methods and a case study in Barcelona, we show that efforts to decrease the costs of a transit system can lead to GHG emission reductions as well. We demonstrate GHG emission comparisons between an optimized bus network design in Barcelona and the existing system. The optimization of the system network design involves minimizing system costs and thereby determining optimal network layout and transit frequency. In this case study, not only does the cost-optimal design lead to a 17% reduction in total costs, but even more notably, the optimal design leads to a 50% reduction in GHG emissions. Furthermore, the level of service to the user is not detrimentally affected and, in fact, it is slightly improved. We, therefore, extrapolate and hypothesize that the optimization of transit networks in many cities would result in significant GHG emission reductions. The analysis in this paper specifically focuses on the effects of bus technology with fixed ridership corresponding to the Barcelona case study, but the methods implemented could be easily applied to other transit modes in different cities.

Original languageEnglish (US)
Article number5
JournalFrontiers in Built Environment
StatePublished - Feb 16 2017


  • Barcelona case study
  • Bus transit networks
  • Continuum approximation methods
  • Cost reduction
  • Greenhouse gas emission reduction

ASJC Scopus subject areas

  • Geography, Planning and Development
  • Building and Construction
  • Urban Studies


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