With the opening of the world's first passenger railway from Liverpool to Manchester (1830) came the first railway passenger fatality and crowd control issues. This prompted public demand for improved railway safety and, just a year after the formation of the world's first police force in London, police officers were commissioned and employed to control train movements in the UK. Some railway police even had shovels and wheelbarrows to clear obstructions on the line and this early incorporation of police in rail safety is thought to have inspired the term 'Police Station' as shelters for the personnel were established every mile along the line. Additionally, in an effort to reduce the risk of train collisions, officers experimented with various techniques and the best was found to be using painted truncheons as a 'token'. This was passed from officer to driver to permit travel to the next checkpoint (a block) - creating the world's first official rail signalling system. This concept evolved rapidly and by 1849, with the introduction of telegraph-based communication, formal signalling controls with bells and signalling boxes were established – the establishment of nascent safety systems. The integration of mechanical interlocking mechanical and then light-based signals further reduced the reliance on physical tokens, especially with the later advent of track circuits and axle counters which circuits detected the presence of a train, allowing more fluid movement along the track without requiring trains to slow to 30 mph to swap tokens.
The simplicity of these early systems made them cheap, reliable, and easily audited for safety. Conversely, in the 21st Century digital systems are expensive, as commercial hardware generally lacks the low error rate needed for railway safety (known as a Safety Integrity Level "SIL"). GPS and similar navigation technologies face challenges in safety audit, reliability, accuracy and security, especially given a world of cyber threats. Of course, a key benefit of digital control systems is increased capacity through minimised error margins. For example, a metro-system that require trains to run every two minutes per direction, with station stops every two minutes, does not have enough margin for driver decision making as all trains need to be instructed to changed speed simultaneously to maintain service. The UK's first automatic metro line, the Victoria Line in 1968, initially alarmed passengers by the lack of a driver in the front carriage, leading to the repositioning of guards. More recently, the Northern Line's £400 million signalling upgrade (and moving block system), which creates a safe zone ahead of each train, was a much cheaper solution than building a new line and in addition increased capacity by 20%.
Unfortunately, economically feasible digital signalling systems are today limited to test beds, such as mid-Wales, and routes with capacity issues such as the Kings Cross to Edinburgh Line and Thameslink in London. Regrettably, nowhere else does the business case for these systems stack up, despite the fact that there is a pressing need for affordable digital signalling solutions that use off-the-shelf digital SIL 4 (Safety Integrity Level 4; extremely safe) systems, automotive level, components to replace ageing, costly, legacy equipment (some of which dates back to the early 20th century...). As a former British Rail Chief Signalling Officer noted, "We build a SIL 4 system and then put a SIL 0 (error rate too inconsistent to measure) human in charge."
So, what are the lessons here? Well, the innovative, hands-on approach of early railway pioneers has given way to extensive risk management and risk legislation driven decision making. This creates a costly vicious cycle as railways increasingly rely on expensive bespoke components. Despite this illogical situation, several companies are working to meet the opportunity it presents, with government-funded initiatives such as the BCIMO/Connected Places Catapult's "Clean Futures Programme" supporting trialling. Notwithstanding this support, the challenges of risk and a restricted innovation environment currently make pioneering implementation in rail impossible for any tech or engineering start up. The potential prize for low-cost signalling solutions and streamlined approval processes is huge; saving billions of pounds from over stretched national and regional transport budgets.
How do we make this happen? The Japanese engineer, Shigeo Shingo (1909-1990) put this very well, "There are four purposes of improvement: easier, better, faster and cheaper. These four goals appear in the order of priority." Perhaps a strategic focus on realising this would promote the benefits of moving block technology, which are considerable: more capacity, improved recovery from delays, and reduced human errors, especially the types that lead to costly accidents. With a recent change in government, the UK is about to enter a potential period of much needed long-term rail infrastructure investment – this could allow profitable rail operations to sit alongside cutting-edge safety innovation, which could inspire innovation in the whole of rail. If you can innovate in safety critical signalling you can innovate anywhere in rail.
