Work on grade separation began in 1970. A number of grade separation projects are planned for the line. This may pave the way for grade separation in the future. The 1896 depot was disassembled in 1912 in preparation for the downtown grade separation. A major change came with the 'Parkdale Grade Separation Project'. The grade separation gradually increases heading south. Expansion continues, albeit with more service and grade separation upgrades as opposed to new lines. The "windmill" serves two arterial roadways by grade separation. A desire for grade separation indicates that a rail alternative may be better. Trains began using the new grade separation in May 2014. These city roads are regional roads without grade separation, and sometimes without a central reservation. Traffic engineers usually refer to the latter as a "grade separation". The city also encouraged the railroads to build grade separation throughout the city. Grade separation is, however, still typical at major junctions. At interchanges, roads pass above or below each other, using grade separation and slip roads.