Construction of Canadian Northern Railway

I'm almost certain that this photo actually shows Grand Trunk Railway employees in the process of laying a second track somewhere between Port Union and Port Hope during the period of 1901-1903. At the very least, I'm confident that it does not show the Canadian Northern line near the Brooklin diamond. Such a deep cut as shown in the photo would leave a scar in the terrain that would still be visible today. While the area is forested now it doesn't appear to have evidence of this cut anywhere nearby.

Between 1881 and 1903, the Grand Trunk gradually double-tracked their entire Toronto-Montreal line. The segment from Port Union to Port Hope was done last, starting in 1901, and involved some of the heaviest work. The right-of-way was realigned in several places, and even parts of the original right-of-way were cut or filled significantly to reduce grades. Relatively few areas were cut as deep as the one shown in the photo, though cuts of a similar depth can still be found east of Bowmanville or west of Pickering. Unfortunately the image shows too few details to tell exactly where this was taken, but I'd bet it's somewhere within the areas I mentioned above.

Additionally, all of the equipment in the photo is lettered for the Grand Trunk Railway. While one could argue that this could have been borrowed by Canadian Northern, I feel that would be very unlikely as they had their own equipment of this kind.