Railcraft Associates Ltd, Consulting Design Engineers


















© Railcraft Associates Ltd 2005. All rights reserved.

Case Study - DLR On-Train Camera Image Protection, 10 May 2006

In the aftermath of the July 2005 terrorist attacks on London Underground, railway operators and security authorities throughout the UK made a detailed review of existing security systems, considering not only means of anticipating and deterring future attacks but also ways to identify those responsible in the event of such attacks happening again.

Many trains are already fitted with closed-circuit television cameras, principally for passenger security reasons and it was recognised that images from these cameras could provide valuable evidence of events leading up to an attack provided the video record was not destroyed in the attack and remained accessible for examination.

An example of an onboard security camera

Docklands Light Railway (DLR), part of the Transport for London regional authority, decided that measures should be taken to secure images from their on-board cameras and Railcraft, as an established provider of consultancy services to DLR, was commissioned to carry out a high level study into how this might best be done.

From introductory meetings with DLR, four possible solutions were identified for investigation:-

Transmit the on-train camera output in real time to a safe location off the train.
Protect the existing data storage device.
Relocate the existing data storage device to a place that is safer and easier to protect.
Fit an additional data storage device in a place that is safer and easier to protect

Using our long experience in rail vehicle design and a good technical understanding of what was required it was soon clear that because of its position and relatively fragile design, neither protecting nor relocating the existing storage device was practical. Pursuing options 1 and 4 therefore, we identified manufacturers of leading edge products in the data transmission and data storage fields for whom we created and circulated a draft specification based on operator priorities and UK Railway Group Standard GM/RT2472 "Data Recorders on Trains - Design Requirements".

The most elegant but also technically the most difficult solution was to transmit the data off the train, however detailed examination revealed that even with the latest radio data transmission methods the data handling rate and storage requirements for a large train fleet were impractical.

The most promising solution realised by the study was to fit an additional data recorder of the new-generation electronic type with a solid state memory e.g. Compact Flash card. This type of device, which is inherently very small, robust and environmentally tolerant, is being developed for demanding military or aerospace applications such as flight data recorders in helicopters and fast jets where temperature extremes and high accelerations make conventional recorders unsuitable.

Data recorders of this type typically have a working temperature range of -40 to +80oC and shock resistance to ± 30g whilst Compact Flash memory cards, particularly the encapsulated type, can withstand much greater accelerations. Several reputable manufacturers of such devices were identified, assessed and their proposals presented in a comprehensive report to DLR with our analysis and recommendations.