. Author manuscript; available in PMC: 2019 Apr 25.
Published in final edited form as: Glob Transit. 2019 Mar 27;1:61–82. doi: 10.1016/j.glt.2018.11.001
This is an open access article under the CC BY-NC-ND (http://creativecommons.org/licenses/by-nc-nd/4.0/).