According to the Swiss Association of Public Transport, there is nowhere in the world where the rail network is so intensively used as Switzerland. At an average of 93 trains per day per kilometre of track there’s no doubt that this is probably the case.  However as train travel continues to increase in the UK, some might argue that some of our main routes are close to capacity and not far behind in terms of train density.

With high train density comes the challenge of maintaining the track and gaining safe access without disrupting trains. It might be no surprise then that ATWS is widely used in Switzerland. Automatic Track Warning Systems (ATWS) use train detection devices fixed to the track and deliver a warning to workers through a series of lights and sounders.  Providing track access to maintenance personnel, there can be as many as 100 ATWS systems in use at the same time on the Swiss rail network.

With a rail network 10 times the size of the Swiss, one might expect there to be similar numbers in use in the UK, however it’s likely that less than 5 ATWS systems are operating at the same time in this country. So why isn’t ATWS more widely used in the UK?

 ‘It’s a lot to do with a perception that ATWS is expensive and an inconsistent implementation of RiMini’ commented Chris Foreman, General Manager of Schweizer Electronic Ltd, ‘although ATWS is taught as part of Personal Track Safety (PTS), there’s not enough understanding of what it does and its cost benefits compared to traditional forms of track worker protection’.

The high cost of line blockages compared to using an ATWS

The cost savings of ATWS can be dramatic when you compare the true cost of using ATWS compared to blocking a line outside a white period. White periods are specific times during the week when no trains are scheduled, and track is available for maintenance work. It is widely reported that if Network Rail blocks a line for maintenance work during a scheduled train service it pays fines to the train operating companies for delays or cancellations. These potential costs however rarely seem to be taken into account when comparing the costs of using ATWS as an alternative.

Short and unreliable possessions reduce productivity

Carrying out maintenance work on the busiest lines under possession is likely to get more difficult as steps taken to implement a 7 day railway continue, particularly when you consider that an extended timetable means more trains with correspondingly more maintenance work, but shorter possession availability to achieve it.  ‘Some delivery units already experience short and unreliable line blockages which impacts on productivity’ said Chris Foreman ‘in addition some contractors have told us that although they pay their track workers for a full shift, they may only get a few hours of productive time on the track. What’s frustrating is that the contractor can see the benefits of using an ATWS system but hasn’t the motivation to use it when the network are happy to pay for the cost inefficiencies’.

A lookout is likely to make a mistake every 1000 actions

Perhaps more concerning than the wasted productivity opportunities, are instances where ATWS has not been fully evaluated as an option before reverting to lookouts. With more stringent legislation, you might expect delivery units to be more conscious of proving that appropriate steps have been taken to minimise risks. ‘ATWS providers still come across instances where ATWS could have provided a cost effective form of work protection, taking less than 25% of the total project time to install it ’, continued Chris Foreman ‘but for whatever reason an ATWS system was not even considered. An ATWS system rated at SIL3 (Safety Integrity Level 3) only theoretically fails once every 10,000 years, or practically never, whereas a lookout rated at SIL0 is likely to make a mistake every 1000 actions’.

With such compelling reasons to use it, how can ATWS providers help the rail industry increase the usage of ATWS and benefit from its safety and productivity improvements? ‘It’s probably just as simple as giving an ATWS provider a chance to quote’ claimed Chris Foreman ‘we believe that most delivery units that trial ATWS will not want to revert back to the traditional ways of warning track workers. At the moment, most use of ATWS in the UK is concentrated to localised areas of the rail network that tried it and now adopt it for much of their works. With CP5 and future rail maintenance budgets under continued pressure, ATWS could help make significant savings, while maintaining high levels of safety’.

With increasing passenger numbers and capacity constraints on the UK’s main routes, some renewals and enhancement projects are suffering with lack of sufficient track access to carry out work activities. Whilst running a Seven Day railway benefits both rail passengers and freight operators, the challenge for the rail industry is a difficult one. More trains, means more maintenance, which in turn means more pressure for line blockages, which disrupts train services itself.

This ‘Catch-22’ situation is felt most by the rail construction and delivery units who can struggle to get a possession on some of the main routes. ‘We are seeing increasing numbers of clients with this type of problem’ says Chris Foreman, General Manager of Schweizer Electronic UK. ‘Clients are under increasing pressure to bring jobs in on budget, but are finding it very difficult when access is limited on complex track. Access arrangements can have a major impact on the cost of delivery’.

Where access is granted, there can be other problems in that short and unreliable possessions impact on productivity. Contractors might get a short possession but still have to pay their track workers for a full shift, even if they only get a few hours of productive time on the track. What’s more, with increased pressure to hand back possessions on time; this access can sometimes be cut short in order to accommodate train services. 

What’s the answer for track access?

Approved by Network Rail, a possible solution is Automatic Track Warning Systems (ATWS). These systems use train detection devices to warn workers and machinery of approaching trains through a series of lights and horns. It’s possible to set up an ATWS on a complex layout within a relatively short space of time. Since track workers are only interrupted by train movements and warnings, ATWS can provide more productive time on the track.

Although regulations regarding Adjacent Open Line (AOL) working have become more stringent recently, there are still suitable sites where ATWS system together with a fence can allow heavy machinery to continue to work next to an AOL. This means that a route can be kept open, avoiding excessive fines on the busiest routes.

Determining worksite suitability for ATWS

‘You’d be surprised how many sites are suitable for ATWS’ says Chris Foreman, ‘giving Schweizer or one of our approved partners a call is the first step to determining suitability. Generally we can tell quite quickly if it’s possible to carry out activities with an ATWS’. As a Safe System of Work, ATWS sites are planned, installed and operated by competent personal.

With most use of ATWS currently concentrated to a few areas of the UK rail network, and with track access and rail maintenance budgets under continued pressure, ATWS could provide the solution that rail construction and delivery units are seeking in order to create safe access, while making significant savings in productivity and reducing passenger disruption.

Schweizer Electronic provides automated warning systems specifically for protecting people and equipment on running rail. Formed in Switzerland in 1964, Schweizer’s core technology is its MINIMEL95 system, a combination of rail-based sensors, a central data processor and a series of warning devices, which offer highly reliable automated protection to work sites.

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.

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.”


6 key considerations in determining suitability of permanent Track Warning Systems (TWS)

Schweizer Electronic have launched a white paper aimed at exploring the difficulties Rail maintenance teams face in attaining the highest level of Safe System of Work (SSOW) under the pressures of increasing train traffic, and proposes a permanent Track Warning System (TWS) as a possible solution to the challenges of obtaining track access.

As rail passenger numbers and levels of freight increase across Europe and the rest of the World, some rail infrastructure companies find themselves in a ‘Catch-22’ situation - squeezing more trains onto the network with less time to close the track to adequately maintain it. All this is made more difficult under a tighter regime of Safe System of Work Planning (SSOW) and optimising the level of protection to the workgroup.

Schweizer’s white paper explains how permanent Fixed Automatic Track Warning Systems (FATWS), Semi Automatic Track Warning Systems (SATWS) or Signal Controlled Warning Systems (SCWS) can provide valuable forms of red zone protection for areas of the track where repeated planned or unplanned P-way maintenance activities take place. As well as 24/7 access, these systems offer manpower savings over other forms of protection, and have the added benefit of providing a favourable business case.

To assess a site for suitability for a permanent TWS, rail infrastructure need to make 6 key considerations:

1. How busy is the track?

Maintenance teams will know the places where they struggle to get possessions, not only for longer blocks but even short possessions in some cases.

2. How many man hours per week are spent maintaining/protecting it?

It is useful to analyse and total how often workgroups are going to the same locations on the track for P-way activities and how many additional protection staff are required. Is access required 24/7, or can it be left for quieter times of the week?

3. What type of work is taking place?

There is a significant amount of regular activities across all the disciplines which could benefit financially from this level of SSOW. When assessing a list of maintenance activities consider whether maintenance work is planned, or can be anticipated as requiring a SSOW from the evidence of past failure data.

4. What’s the most difficult topology of track maintained by the depot?

Consider which areas of the track are notoriously difficult to protect in a Red zone. For instance a busy junction, with 2 or more routes merging can require several traditional or LOWS lookouts to provide adequate warning. Reverse curves may require assisted lookouts, and radio reception for LOWS could be affected by deep cuttings.

5. Can you build a business case?

Use the information gathered so far to structure a favourable business case and payback calculation. Moreover consider if permanent TWS can improve performance reliability and journey times for passenger and freight services, providing longer term revenue improvement for the Rail Infrastructure Company.

6. What technology is available to provide a solution?

When selecting a permanent TWS solution it is important to consider whether the technology is reliable and has the capability of managing the complexity of track. An assessment of the manufacturer’s history is also crucial to judge their expertise in work protection and long term permanent TWS sites.

To download a copy of the white paper, access Schweizer Electronic’s website at:

With over 45 years of experience, Schweizer Electronic provides temporary and fixed Track Warning Systems (TWS) which improve safety and access to running rail in a red zone environment. Approved for use in many countries across the World, its track worker protection systems use failsafe SIL3 accredited technology which can be configured for most worksites.

For more information, view our website at 

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