I don't undersatnd this taking the DRL in the east all the way to Sheppard yet somehow in the west it can't even go up to Weston on Eglinto.. This does not make saense to me. And considering lack of ridership on Sheppard I do not seee why getting the DRL up there is a prioroty over getting the DRL up to Weston Rd and Eglinton which makes more sense.
You need to look at the big picture and it includes future development as well today transit issues. Today issues are compounded by the future needs.
I am only looking at the eastern leg and that is where you will take most of the riders off the Yonge Line going to Steeles.
If you look at the ridership on all the lines feeding into the Yonge line and take 35% of those numbers, that is what the DRL will be today if the line was there today.
The south-east corner of Sheppard and Don Mills is going to increase 50% in size and residents with almost 35% new development built now. There is another project down the street doing almost the same as well one plan for Finch. You have Concord Place to the West of the Sheppard intersection similar to City Place that will have the choice of using GO or traveling 1 stop to the DRL than go to Yonge.
There are a vast number of development on the books for the major east-west routes that will increase ridership on the DRL as well noted above. In time, the numbers on the DRL will increase to what the Yonge Line has today.
There are vast number of projects underway along the Yonge Line, on the books to be built that those new riders will replace the ones using the DRL. If you look the Yonge Street from Steeles south, there are great number of areas waiting for development plans and these non projects at this time will replace all the riders that have move to DRL 150%. Between the current development taking place as well the non ones, the Yonge Line will exceed it capacity before 2050 that a new Yonge Line will have to be built, but not like it is today.
The DRL going to Danforth is only taking some pressure off the Yonge Line south of Bloor, but going to be replace by the new development underway or will be built in the next 10-15 years. The 3 corners of Eglinton & Yonge are to see major development by 2020 as well along Eglinton that are underway or plan. You need to look at a 3 block radius around this intersection to see what has been built in the last 5 years, underway and to be built by 2020. That one hell of an increase of ridership for the station and the line south of it.
If I look at the west section, the ridership as well development doesn't support the line at this time, but most of all where it goes north.
I have always seen the line going over to Jane St and then north on it since Jane can't support a surface ROW until Wilson, but you can try it at Eglinton.
It will take decades to get any development in the west to come close to the east.
I saw the western leg going up Jane to Major Mack before the Spadina extension surface and got underway. It still can happen by having both lines interline north of Steels as a Wye.
The western section of the BD sees more riders than the east today as well most of its history. The University Lines save the Yonge line from these riders as long they have no need to use Yonge in the first place. I have started to use the University line at PM peak as I can catch a train most of the time compare to waiting for 6 trains going north on Yonge line