In an age of automation, rail track workers still rely on human lookouts to warn them of oncoming trains. It doesn’t make safety or financial sense, says Schweizer Electronic.

Everyday as work continues on maintaining and improving the UK’s rail network, teams of workers rely on human lookouts to warn of oncoming trains. Pressure to keep tracks open during repairs means there can be thousands of lookouts, each one a skilled worker, but otherwise unproductive during their duties. In a world where public transport must become increasingly competitive, why can’t the safety of track workers be dramatically increased, while at the same time improving productivity, through automating the detection and warning of trains?

Minimising risk

“Where a system relies heavily on automation, the most likely cause of problems is human error,” comments Stefan Schürch, Business Unit Manager, Work Protection, at Schweizer Electronic. “Research in this area shows that, during periods of concentrated effort, a worker will make one error in every thousand actions. Consider that a lookout requires rest, food and breaks, and his judgement may be affected by weather, uneven terrain or poor light. He may even have to work at night, when he is more prone to fatigue. Given the nature of rail tracks and trains, this raises the error rate to above what we believe is an acceptable level.”

Swiss-based Schweizer Electronic focuses on automated warning systems specifically targeted at protecting people and equipment on operated rail tracks. A developer of high-security radio and data transmission systems, it has projects throughout Europe in the transportation safety industry.

“Given the relative danger of working on rail tracks and the potentially serious nature of damage to individuals and equipment, our focus is risk minimisation,” continues Schürch. Schweizer’s core technology is its MINIMEL95 system, a combination of rail-based sensors, cables, a central data processor and a series of audio and visual signalling devices, which offer highly reliable automated protection to work sites. MINIMEL95 is certified by TÜV-Eurorail to a standard called SIL-3 (safety integrity level), which means an allowable failure rate of one error per ten thousand years of operation – effectively, never. Sensors are located on rails at a defined distance from the worksite, and when a train passes over a sensor, a signal is transmitted to a central unit on the site, immediately triggering an audiovisual warning signal. Once the train has passed the worksite, sensors at the far side automatically switch off the alert. The process is classified ‘failsafe’, meaning that even in the extremely unlikely event of error, warnings are given, enabling the failure to occur safely.

Automated warnings cost less

The savings from redeploying lookouts to the rail work itself is vast - for a national rail operator with up to 200 worksites running in parallel, it can be thousands of pounds per day adding up to millions per year. Add to that efficiency savings when work is completed sooner, and fewer penalties for delayed trains, and the savings multiply. “Automated warning systems are a legal requirement across much of Europe, because of the safety benefits” concludes Stefan Schürch, “but when the cost savings are so huge it becomes an obvious step.”


For over ten years Track Warning Systems have been hyped as a track safety and productivity solution. The reality was minimal use and failed pilot schemes such as Automatic Track Warning System (ATWS) installation at 17 key locations in 2002 that were soon removed. Also the Track 02 system that lost its safety approval in 2004 after over a hundred sets had been purchased by Network Rail’s Contractors. Now times are a changing with Network Rail’s successful large scale LOWS initiative. Does this mean a brighter future for Track Warning Systems? With the next generation of ATWS under development, and McNulty requiring the adoption of more efficient continental practice, it would seem so. The Rail Engineer visits ATWS suppliers Zöllner and Schweizer to learn more.
Large scale LOWS use

Zöllner’s Frank Peters states that 230 portable LOWS kits have been supplied to Network Rail’s maintenance teams over the past two years. He knows this kit is intensively used as Zöllner have been closely involved in its introduction providing training, a hotline, servicing, repair and annual recalibration service. Frank says “initially we were called out quite a bit, but less so now, as depots get used to the kit”. Network Rail’s standard NR/L3/MTC/SE0206 “Introduction and Management of LOWS Equipment” specifies the competence for its use and the support to be provided by Infrastructure Maintenance Delivery Managers (IMDMs) which includes the need to map locations to establish a pre-determined Safe System of Work (SSoW) and to confirm of radio coverage. Training is the same for the LOWS Controller and the LOWS Lookout. The LOWS competence is deemed to have lapsed if it is not used within 28 days of initial training. Thereafter LOWS must be used at least 10 times in the next three months and once every three months after that.

Network Rail’s successful LOWS implementation is due to the work of Track Warning Systems (TWS) Steering Group and those in the maintenance organisation who have driven its introduction though some depots immediately saw its benefits and made more use of LOWS than others. No doubt the use of LOWS will increase as, with large scale use, its benefits become clear to all. The time to set up and test a LOWS SSoW is very similar to that for conventional Lookout.

Zöllner consider that by far the greatest use of LOWS is mobile patrolling with LOWS Lookouts who remain static but can leapfrog each other as the patrol moves in accordance with the pre-determined SSoW determined by the mapping exercise. Previously it was often not practicable for mobile Lookouts to maintain the required sighting distance and mobile workgroups accounted for a large percentage of track fatalities so mobile LOWS use offers a significant safety benefit. Other advantages are that, at night and in fog, there is no need to impose a 20 mph TSR as the LOWS Lookout can be positioned where the train passes. Also the LOWS Lookout need not be on the rail infrastructure. For example a bridge over a steep cutting offers improved radio coverage, increased sighting distance and a less hazardous situation.

The Status Quo, our greatest competition

Although both Schweizer and Zollner supply Track Warning Systems, Schweizer’s Chris Foreman feels that his “greatest competitor is the Status Quo”. On the Swiss rail network, which is less than a quarter the UK network, he estimates use of ATWS to be between 50 and 100 per day. Both Chris and Frank estimate that ATWS use in the UK is 5 to 10 per day. Chris clearly believes large scale use of ATWS would benefit the UK rail industry but feels that current arrangements do not provide sufficient incentive for its use as “Programme Managers have to pay for ATWS but do not get the financial benefit from engineering access savings”.  Chris considers that the McNulty report’s benchmarking UK rail against European practice should drive increased use of ATWS. Frank Peters thought it odd that although the RIMINI standard requires ATWS to be the first consideration for Red Zone working, its use is a tiny percentage of Red Zone working. He also felt that ATWS use needs to be considered earlier in project planning.

Unlike LOWS, ATWS automatically detects trains by rail mounted treadles or sensors so has a higher Safety Integrity Level with manpower savings, particularly at junctions. The system comprises of detection, processing and warning modules that can be connected by either radio or cables. Although radio offers quicker set up times, radio equipment is more expensive than cables and requires daily battery change.
Both Schweizer and Zöllner supply equipment to companies who offer ATWS solutions. Schweizer supply their Minimel 95 equipment to McGinley and Rail Safety Solutions and Zöllner supply their Autoprowa equipment to Vital Rail and Rail Safety Solutions. ATWS works well at sites of a long duration. Chris gives the example of BIRSE’s construction work at Southend Airport station where ATWS facilitated access to speed up the project. Frank offers the example of ATWS equipment on the Forth Bridge minimising the risk to trains by warning Balfour Beatty’s scaffolders to ensure items are secure as trains pass underneath them.

The Next Generation

Both Schweizer and Zöllner are about to launch their next generation Track Warning Systems onto the UK market and expect to get product approval soon. When approved, both of these new systems have new methods of installing train detection treadles enabling them be installed in 5 minutes (i.e. between individual trains), bi-directional radio which provides the LOWS Lookout with confirmation of the warning on site, have movement detection as a deadman’s safety device and use less energy and so  are lighter than previous systems. This will give Schweitzer a fully portable LOWS system. Zöllner’s new system uses a Lithium Battery with its own charge indicator and with an optional increased maximum warning sound to 120dB although usually the warning will be less than this as Zöllner’s Autoprowa system has microphones to ensure that the warning is appropriate to the ambient noise level. Schweizer will have repeaters to ensure signal strength.  Both these systems have been already been approved in Europe by independent safety assessors, Technischer Überwachungs-Verin (TÜV). Frank Peters feels that in recent years Network Rail’s “acceptance process is now more professional” with TÜV technical approval accepted, product approval primarily concerns integration with UK methods of working.

One of the features of the new Zöllner and Schweizer equipment is that it will no longer be necessary for each control unit to be individually manned. As a result long worksites need only have one LOWS controller. Frank advises that Amey Colas are keen to use this new equipment so that LOWS can provide warnings to staff on the open line adjacent to their High Output track renewals sites.

Controlling the risk to trains from engineering work

ATWS equipment can be used as part of a safe system of work to protect trains from engineering work, as illustrated by the Forth Bridge example. Chris Foreman advises that Schweizer are developing a system to control the risk to trains on the adjacent open line from machines working in an adjacent possession enabling such lines to be kept open. This is based on a 2004 pilot scheme which used ATWS equipment to warn machine operators of approaching trains. When it was then confirmed that machines were not foul of the open line, a detonator placer removed detonators from the line. This method of working was subsequently adopted by the Rule Book. Schweizer’s system uses an emergency red light and temporary TPWS loop to stop trains unless there is confirmation that the line is not fouled by machines.

Using signalling system to detect trains

Using the signalling system to activate a track warning trains offers instant set up times and reduce costs associated with train detection. It also reduces unnecessary warning as, unlike ATWS, the signalling system takes account of the position of points and trains being stopped at signals. In the UK, use of the signalling system to provide track warning is confined to small scale use of TOWS (Train Operated Warning Systems) on plain line track, in contrast to more sophisticated systems in Europe.