frequencies in the 3.5 minute range would require grade separation on all but the absolute lowest traffic crossings. You would probably end up with more time with the level crossing gates down then up for that level of frequency - trains would be going by every 1.75 minutes.. leaving a window of maybe 45 seconds to a minute for cars to pass.
Luckily, GO has several parts of it's network which are entirely grade separated (or are planned to be from GO Expansion), and several more which are very close to that level.
- Stouffville from Unionville to Union
- Lakeshore West from Long Branch to Union
- Barrie to Caledonia GO
- Kitchener to Malton GO
- Lakeshore East to Eglinton GO
Several other corridors mostly have minor crossings remaining, or only a handful of larger road crossings which need to be addressed:
- Barrie could probably see 3.5 minute service fairly easily to Maple, provided Langstaff and Rivermede were seperated.
- Lakeshore West could probably see it on the entire corridor provided that something was done with Fourth Line, Kerr St, and Lorne Park Rd.
- Lakeshore East could probably see it on the entire corridor already, but may need Scarborough Golf Club Road done.
- Kitchener could easily extend service to Bramalea, with only 2 small at grade crossings.
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