nzqf182 wrote:AKL_Train_Driver wrote:
Not strictly a train photo, but more a drivers' eye view arriving at Otahuhu...
More to follow soon!
What does it mean when there are two sets of lights on a signal pole.
Cheers, nice photos
Ok, I hope this makes sense! Kind of a crash course in signals! The signal in the above picture (up home for Otahuhu) has 3 light units. "A" unit (3 aspect on the top) "B" unit (3 aspect below), and "C" unit (low speed light backed with a white triangle (with a yellow border, for the picky drivers on here!!!)). In NZ we operate a speed signalling system as opposed to a route signalling system, but depending on the signal displayed, it is possible to work out what route is set.
Each of the three units have a speed assigned to them depending on what is being displayed. The "A" unit is used for "Normal Speed" indications, the "B" unit is used for "Medium Speed" indications, and "C" for low speed. For example, the above signal is displaying "Caution, Normal Speed", the next signal in advance will be at stop. If the top signal was green, it would be "Clear, Normal Speed", the next signal in advance will be at proceed.
At different locations, such as Westfield junction, the "B" unit can also display an "intermediate Speed" signal, as a flashing yellow or green indication. Medium, Intermediate and low speeds are displayed when diverging onto another line. If the above signal was displaying red top, yellow bottom, "Caution, Medium Speed" the train would be going onto the "Down" line at Otahuhu platform.
I hope that kind of makes sense. I must say that it's a very stripped down explanation as the signals section of the rule book is quite a few pages long!