Wednesday, September 24, 2014

Setting up Simulations of the DRL

With all the talk this year of transit issues in Toronto and the importance of building some sort of downtown relief line (DRL), I thought I would try to grab some open data and see if it's possible for amateurs to gain some insight into the problem.

The current argument behind the downtown relief line is that most people want to go downtown for work. Also, the population of downtown is exploding in itself because both the millenial generation and the aging boomer generation are favouring the downtown lifestyle over the suburban lifestyle. This is supposedly causing a number of problems. The primary means for getting into downtown is the Yonge subway, and it's always full. It's so full that one of the main arguments against extending the subway system in the suburbs is that these extensions would simply feed more traffic onto the Yonge subway, which can't handle the additional load. Since the whole system relies on the Yonge subway line to move people into downtown, if there are any problems on that line (which happens often), the whole transit system grinds to a halt. There is very little redundancy in the system to provide riders with alternate ways to get downtown if the Yonge line has problems. A related problem is that the Bloor subway feeds riders onto the Yonge subway at the Bloor-Yonge station, and supposedly that station is also becoming a bottleneck in the system too in that it's becoming physically difficult to transfer all the people from the Bloor subway to the Yonge subway because there's just too many people. And then there's also a concern that the primary means of moving people east and west through downtown--the streetcar system--can no longer handle all the people who have now moved downtown.

The primary goal of the DRL is to build a new north-south subway line to relieve the pressure on the Yonge line. Since people primarily want to ride the subway into downtown, this DRL will also have to go into downtown somehow. If the DRL also happens to relieve pressure on the east-west streetcar system, that's a bonus.

To gain some insight into different DRL plans, I've started setting up a simulation that shows who is riding the Yonge subway now. I took the GO Transit and TTC schedules for September 24, 2014, and I calculated the optimal route for people who need to get to work at Bay and King at 8:55am and 9:00am. I tracked whether the route used the Yonge subway south between Queen and King as an indication that a particular route used the Yonge subway. I also tracked which routes used the Bloor line through Bloor-Yonge station and also use the Yonge subway between Queen and King as an indication of riders who transferred from the Bloor to the Yonge subways. Since I calculated routes for two different times, it's possible that different routes are optimal for those two times. Since the two times are only 5 minutes apart, I assumed that riders would take the route that avoided the Yonge subway, if possible, and if not, then one that avoided a transfer from the Bloor subway to the Yonge subway.

The result of the simulation is shown below. The red dots show areas where people can get to downtown without needing to use the Yonge subway. The yellow dots are areas where people's optimal route to downtown involves taking the Yonge subway. The green dots are areas where people's optimal route to downtown involves riding the Bloor subway to Bloor-Yonge station, and then taking the Yonge subway into downtown.

As can be seen on the map, everyone in the west of the city can take the University-Spadina subway line into downtown, so that area is all red. Surprisingly, it is often optimal for people just to the east of the University-Spadina subway to still travel further east to the Yonge subway line to get downtown.

In southern east York, the fastest way downtown seems to involve taking the streetcar. In south-east Scarborough, I think the fastest way downtown involves taking a bus down to the Lakeshore GO train possibly? Or possibly TTC express buses direct to downtown? Or GO buses? It's hard to tell.

There's an area around the DVP where I think it's fastest to use express buses from the TTC or GO to get downtown rather than travel east or west to a subway line. Those also sporadic red spots in places around GO bus stations and GO train stations. These stations offer quick ways to get downtown, but they don't come often enough to make it worthwhile to take them if you need to get somewhere by a certain time unless you live really near to the stations.

Anyway, that's just a preliminary map of what I can calculate using the readily available transit schedule information. I'll later try plugging in some suggested DRL plans to see what effect they have on the map.