Animated spawn camera - using a cross-hair guide to animated geometry

Reimporting the escalator asset into a new scene. The transition between Sally's world will be an escalator that arrives slap bang in the midst of Piccadilly Circus. Taxis driving past, rain, road water splashes and an animated bus with moving colour to represent metal catching surrounding lighting, are the immediate scene at the top of the escalator.

The spawn camera is set on the escalator and, using transform animation keys, moves slowly as if the viewer is on the escalator.

A stepped interpolation, meaning a jump between animation movements, rather than for example the smooth transition of a liner interpolation, means that I could reposition the camera. Snapping onto the top of a sight-seeing bus, the viewer is immediately transported and moves through Piccadilly Circus.

Ideally the spawn camera would be placed in a group folder with the bus. The group folder would have transformation keys applied, so that all 'children' within the folder would move simultaneously and follow the animation path of the parent folder. However, having the spawn camera in a folder with a moving bus would have affected the camera path on the escalator, causing it to follow the path of a bus on the other side of the scene. 

Therefore, to match the camera to the bus, so that the viewer can sit on the bus and have the experience of moving, I created a cross hair view in the spawn camera folder (see red cross hair in screen shots below). Selecting the cross hair and the Quill command of 'copy paste to new layer' meant that I had a duplicate cross-hair, whilst retaining the original cross hair. I re-coloured the new cross hair bright yellow and placed it in the folder containing the top deck of the London bus (no need to create the rest of the bus in detail, as the viewer won't see it). The yellow cross hair creates a marker position, identical in location to the camera cross hair. So when the bus moves, I just need to make sure that there is a corresponding frame at the beginning and end of the transition movement of the bus, and place the camera cross hair in the same place. Making sure that the interpolation for both the bus and the camera animation are the same, the two will run together, as if grouped in a folder.