Jarrett Walker, a transportation consultant and the author of the book Human Transit, says "Sheppard's technology makes it both expensive to abandon and expensive to extend; that's the trap."[REF] .
Councillor Josh Colle, who has been chairing the TTC since December 2014, said in May 2015 that, given the existing Sheppard subway's performance, he cannot rationalize spending more money to expand it east from Don Mills or west from Sheppard-Yonge.