It could be argued that Scarborough lacks the density to justify a subway extension, but it sure didn't lack the political will; They wanted their subway, and now they will get it for a whopping price tag of $5.5 billion.

But there will be other costs that can't be expressed in dollar signs.

The Scarborough Subway Extension won't come online until 2030, and with the Line 3 Scarborough RT to shut down in 2023, the former borough is going to have to contend with a whole lot more surface traffic in the interim.

In a huge downgrade from train service, the TTC has stated that "parts of the existing Line 3 right-of-way [will] be converted for dedicated bus operation to provide customers with the quickest and most reliable service."

But that would only cover a section of the bus replacement route, and the gap in this temporary busway would be filled by good old-fashioned city roads.

The TTC has released a report with final recommendations for the Line 3 Bus Replacement Study, which outlines how 70 additional bus trips will be needed per hour to offset the loss of the Scarborough RT.

Midland Ave: where #TTC proposes running up to 70 southbound replacement buses / hour when the Scarborough RT closes in 2023 & while a busway is built in RT corridor.

Join the online training April 11 at 6pm to learn about TTC's plans & how to have a say:https://t.co/808WAjsZAP pic.twitter.com/bwaEBfYaXx

— TTCriders (@ttcriders) April 10, 2022

The report states that temporary infrastructure, including additional platforms, will be needed "to accommodate the additional 70 bus trips per hour that will operate from Kennedy Station as a result of the Line 3 bus replacement service."

The replacement service will also require the construction of temporary bus terminal platform modifications at Scarborough Centre Station and at Kennedy Station.

All of this planned disruption has one transit advocacy group pushing a petition asking for dedicated bus lanes along these stretches of Kennedy and Midland that one-way services will share with cars, cyclists, and pedestrians.

When the Scarborough RT closes in 2023, #TTC will add 70 buses/hr in peak periods (more than 1 bus/min) to replace train service.

That's why we need dedicated bus lanes!

Sign the petition before City Councillors vote Thursday: https://t.co/uphquqombx

Image: @BrimleyTripper pic.twitter.com/BusxNSeu8r

— TTCriders (@ttcriders) April 12, 2022

It will be a massive influx of buses for Scarborough streets, though TTC spokesperson Stuart Green points out that the 70 buses per hour statistic is a bit misleading, clarifying that "it's a two-way route, so you wouldn't have 70 in one direction."

Still, the added presence of all these buses could cause headaches for local traffic.

While the common assumption that Scarborough is home to a high proportion of car owners is probably overblown, local drivers will still be dealing with over one bus per minute, per direction on stretches not covered by the temporary busway.

And anyone who rides TTC surface routes knows that all it takes is a slight bottleneck to turn an orderly bus procession into commuter chaos.