OPO Platform Crowding Obscure View
On several lines, London Underground operates, a Track-to-Train One-Person-Operated closed-circuit TV system (OPO TTCCTV). It captures and transmits real-time video images of the Platform-Train-Interface (PTI) directly to the driver’s cab.
- The trackside transmission equipment has at least one RF transmitter for each permitted direction of travel on each platform.
- It transmits two distinct radio-frequency signals (one for each in-cab monitor) at pre-set frequency bands. 20 channels between 31.0 and 31.3Ghz and 20 channels between 31.5 and 31.8Ghz, are available.
- On each trackside there are a number of short-range RF transmitter ‘beacons’. They switch the train receivers to the correct pre-set frequency and turn the receivers on or off, according to their location on the track relative to the train, and according to the permitted operational moves on each platform.
Description of Works Carried Out
Across several OPO TTCCTV projects, ADComms has designed, built, installed and commissioned all the camera, video processing and transmission systems. We provided all engineering disciplines (communications, electrical, mechanical, civil and human factors) and were Lead Designer for the Detailed Design stages (equivalent to RIBA E/F and GRIP 5).
The cameras are very precisely positioned along the platform, with the focus, zoom, elevation and rotation carefully adjusted to provide full images that meet strict acceptance criteria of coverage, image height and ‘cross-over’ between adjacent images. Further to this, experience at London Underground shows that crowd behaviour at the platform edge can significantly obscure the images seen by train drivers.This three-platform project modified the design and camera locations of the OPO TTCCTV to address the crowd behaviour issue.
The ADComms design function generated all the required assurance documentation for the entire build and commissioning phases. This included comprehensive ‘Verification and Validation’ plans, detailed test schedules and documentation, and Inspection and Test Plans.
Commissioning and passing of the system into operational service is of utmost importance. Strict assurance processes were defined by the design to ensure preliminary testing was conducted without disrupting the operational system. ‘Cut-across’ was done within a single ‘engineering hours’ shift to allow ‘operational acceptance and sign-off’ of the new/modified OPO TTCTV system, with the first train following ‘traffic’ hours.