Why isn't the subway image more passenger-friendly?
The subway image that you see on your monitor has been electronically
captured from the screen of one of the computers Muni uses to
control subway trains. The symbols and layout of this screen were
designed to be used solely by expert Train Control operators, not to
give information to the general public. For train information
specifically designed for use by the public, please visit Muni's
Does this image show what is happening in the subway at the
time I download it?
Yes. A new subway image from the Central Train Control operator's screen
is captured every 5 seconds. This means that the image is at most
seconds old (plus the time it takes for your computer to download
it). Each time you click "Update Snapshot", the most recent
subway image is downloaded to replace your current one. The white
timestamp in the lower right corner tells you when the image you are
viewing was captured.
Why is the line letter (J, K, L, M, or N) of some trains black,
while other trains are light-colored?
Trains whose letters are black are being controlled (i.e.
"driven") by the central Train Control computer. Trains
whose letters are white
or yellow are being driven by the train operator. For various
operational reasons, both types of trains are often seen in the
subway at the same time.
What does a dot (instead of a number) in a train square mean?
A dot means the train's doors are open.
Why are some track sections red instead of the normal light
Tracks are shown in red when they have been "closed" by a Central
Control Operator (CCO) or the Train Control system.
Computer-controlled trains cannot move in a closed track section.
The short track sections that are seen above and below the main
track between Castro and Forest Hill stations are red because they
are kept “closed” during normal operation. Tracks may also be closed
for short periods. A CCO might close tracks, for example, to allow
personnel to work safely on the track. In addition, the Train
Control system will automatically close tracks if it detects an
intrusion or cannot verify the safety of all vehicles in the track
There are small colored spots along the track in front of a
train. What do they mean?
The little spots along the track show the route
that the train will be taking as it moves down the track.
Can the size of the image be changed?
No. It is permanently 630 by 272 pixels and is based on the
resolution of the Central Train Control operator's screen, which is
permanently fixed at 640 by 480 pixels. The higher the user's screen
resolution, the smaller the image will appear on it. It will not
lose any sharpness, however.
Copyright © 2010 San Francisco Municipal Railway.