Boards placed high on catenary masts with (usually black on white) symbols such as a diamond outline, a cross, and a vertical line with two breaks in it. These indicate the neutral sections.
The diamond outline often has a distance (‘500m’) marking in it indicating the distance to the neutral section. (Sometimes a warning sign such as ‘Dead Zone Ahead’ (black on white) is also seen.) Usually one such sign is provided 500m before the neutral section and another 250m before the neutral section. At the sign 500m before the neutral section, the loco is powered down by bringing the notch lever down to 0. The driver is also supposed to start switching off the blowers and other auxiliary equipment. By the time the sign 250m before the neutral section is reached (just 10-15 seconds later at typical speeds), all the auxiliary equipment should be switched off, although this is not always true. The older signs are black on white. Newer signs with reflective paint are now in use [1/05] in some places. The 500m sign in the newer scheme is blue with white letters and a white diamond symbol; the 250m sign is white with red letters and diamond.
A cross figure (with the vertical bar broken and not touching the horizontal bar) is the sign just before the neutral section advising the driver to open the DJ (main circuit breaker) for the loco. This is mandatory if the sign is on a post with a white or yellow base. Older signs of this type black on white; newer ones with reflective paint are white on blue.
Immediately after the neutral section a sign with a vertical bar broken at two points is displayed. This advises the driver to close the DJ (BLDJ closed while depressing BLDJR switch simultaneously to close the main circuit breaker) and turn on the auxiliary equipment. Again, the older ones are black on white while the newer ones are white on blue.
Sometimes instead of explicit graphics depicting the pantograph being raised or lowered, three vertical bars one above the other with the middle one displaced sideways from the other two are shown as instructions to raise or lower pantographs before the neutral section. These are mandatory if posted on yellow or white bases.
All these figures are black on white. Any of these may appear more than once near a neutral section, once in plain (unannotated) form for normal trains, and additional signs annotated with the word ‘EMU’ or ‘MEMU’ specifically for multiple-unit trains.
Unexplained sign #1 Near the top of the catenary mast, a square board with a circle in it; within the circle ‘B’, a red disk, and ‘T’ in a vertical line. Perhaps something to do with the provision of booster transformers??
Unexplained sign #2 Near the top of the catenary mast, a square board with a blue disk, and the word ‘MEMU’ on it. This is thought to be an instruction to MEMU drivers to close the DJ — since MEMU rakes can have more than two pantographs, it can be difficult for the driver to tell when the last one has passed the neutral section.