Energy Use of Subway Networks in the Sustainability era 1 Sybil Derrible, Ph.D. Candidate, Department of Civil Engineering, University of Toronto CORS-INFORMS International Conference – Toronto, ON June 15, 2009

2 Rationale Current Work: Networks Effects – Coverage, Directness, Connectivity

3 Rationale Networks Effects - Applied Getting to Carbon Neutral: - Best Practices - Rules of thumb TTC Network in 25 years?

4 Context - In the battle towards reducing GHG emissions, cities are of paramount importance (Copenhagen climate conference, December 2009) - Transportation is one of the core issues - Due to their environmental benefits, public transit systems are likely to grow - It is clear that public transit is most often more environmentally sustainable than private automobiles, but: What is the impact of network growth on energy use of subway networks?

5 Framework What does energy use mean? - A larger network will emit more because it carries more riders, is it more sustainable or less? - If we account for passengers: should we use energy per ride (boarding) or per passenger kilometres travelled (PKT)? - Note: talk about energy use, not emissions of tCO2e because the energy grid is not known, and does not add information about the sustainability of subway networks → prefer to use energy use per ride (total boardings or boardings per capita)

6 Framework What directly influences energy use? - Size of the network (route length) Tokyo (292km) vs. Toronto (69km) - Number of operating subway/metro units (wagons) London (3900) vs. Athens (216) - Vehicle Technology

7 Framework How to use network characteristics - Absolute Values (as collected) - Relative Values (route length by population, metro units by population) → prefer absolute although consider differences during the analysis

8 Dataset and Sources Dataset: - Originally planned to study 19 subway networks in the workd - Narrowed down to 15 cities due to data availability Sources: - Route length: from each individual transit authorities (2008 data) - Energy Use and Metro Units: Millennium Cities Database (1995 data) Note: consider systems that have undergone few changes only

9 Results - partial City Boardings (million) Route length (km) Metro Units Total Energy Use in TJ Energy per unit (MJ/km) Toronto Montreal Chicago Washington DC San Francisco Mexico City London Paris Lyon Berlin Athens Stockholm Tokyo Osaka Seoul

10 Vehicle Technology Should we take it in account? We will see that network characteristics are more relevant

11 Boardings and Network Characteristics Impact of Route Length

12 Boardings and Network Characteristics Impact of Route Length

13 Boardings and Network Characteristics Impact of Number of Metro Units

14 Boardings and Network Characteristics Impact of Number of Metro Units

15 Network Characteristics Route Length vs. Number of Metro Units

16 Energy Use and Network Characteristics Energy and Route Length

17 Energy Use and Network Characteristics Energy and Number of Metro Units

18 Energy Use and Boardings Energy and Boardings Is there a Relationship?

19 Energy Use and Boardings

20 Energy Use and Boardings Perhaps the San Francisco BART is too long or network design could be optimized

21 Energy Use and Boardings Perhaps Chicago is too “long”, similar to San Francisco But still, it is has long as Mexico city, are there any other reasons

22 Energy Use and Boardings Are these networks “under- utilized”? (Characterized as Regional Coverage and Directness) What about Network Design?

23 Energy Use and Boardings Could these networks be “over- utilized”? The smallest systems (Athens and Lyon are along with the largest (Tokyo, Paris). What about their design?

24 Energy Use and Boardings What about these networks?

25 Conclusion - We looked at 15 subway networks in the world to investigate the impact of network size on energy use - Evidently, Total Energy Use of Subway systems is highly correlated with network size - However Energy Use per Ride seems to be relatively independent of network size - Emphasis is put on NETWORK DESIGN since it is correlated with Ridership - New projects should therefore focus on network design in order to favour ridership, which will in turn minimize energy use per ride

Questions 26 Questions? Sybil Derrible Thank You