Go back and look at the first picture. There were only four main lines. Starting at the right they were #1, #2, #3, and #4. Judging by this, and that there are only two tracks on the Bay side of the train, it's on #3. If you zoom in, #4 can be seen just beyond 3. The second pic shows that my assessment of the left-hand signal as being for #3 was incorrect (it has been at least 30 years), however it still doesn't show the all air-operated semaphore adjacent to the business car spur, which is on the left, and 16th St Tower.