Greater Toronto Transportation Authority - the former legal name of Metrolinx, the Ontario provincial agency responsible for transportation planning in the Greater Toronto Area and Hamilton
He was instrumental in petitioning Metrolinx to include a station at Oakwood Avenue in their final plans for the Eglinton Crosstown LRT.
There has been some discussion of re-using the site as a GO Transit station on an extended Lakeshore East line which would run right in front of it, but Metrolinx and the properly owner did not reach an agreement.
On October 12, 2006, Ontario Minister of Transportation Donna Cansfield nominated MacIsaac to be Chair of the Greater Toronto Transportation Authority, which is now known as Metrolinx.