1. What does ATWS, LOWS, SCWS and TWS stand for?

ATWS - An Automatic Track Warning System which detects trains and gives a warning automatically. The system counts further trains and turns itself off when all the trains have exited the worksite.

LOWS - Lookout Operated Warning System which is activated manually by a lookout. The warning is sent via a radio signal to a warning unit on the worksite. Trains are counted down by the LOWS COSS who turns off the warning when all the trains have exited the worksite.

SATWS - Semi Automatic Track Warning System detects and count trains automatically, but trains are cancelled manually by an operator.

SCWS - Signal Controlled Warning System uses a read feed from the signaling interlocking system. Data including train route and signal status are interpreted and compared with the track topology to activate a warning. The warning is turned off automatically by the system when the train leaves the worksite.

TWS - Track Warning System is a collective term for ATWS, LOWS, SATWS and SCWS.

2. How safe are the systems?

ATWS and SCWS are both rated at SIL3 (Safety Integrity Level 3). Theoretically there is only a 1 in every 10,000 year chance of failure, or practically never.

Although communication between the LOWS components is rated at SIL3, the overall system is rated at SIL0, similar to a traditional lookout with flag and horn. Theoretically at SIL0, a lookout will make a mistake 1 in every 1000 actions, as they are prone to human factors such as lack of concentration and risk of errors.

A SATWS provides automatic announcement of trains at SIL 3. Accordingly they offer a higher safety level than LOWS.

3. Can you use an ATWS or LOWS at night?

Both ATWS and LOWS can provide a SSOW (Safe System of Work) at night. At night we recommend that track workers are no further than 25 metres from a warning device. Where lights only operation is permitted, 2 warning devices should be used.

4. Can you use your LOWS and ATWS on the UK rail Network?

Our Minimel 95 LOWS and ATWS have been approved by Network Rail since 2002.

5. How much does it cost to rent an ATWS system?

Obviously the cost of renting an ATWS very much depends on the complexity of the track being protected, in terms of number of lines, direction of travel, crossovers etc. Although there is an upfront cost of installing a temporary ATWS site, an ATWS will generally provide a favourable payback to the infrastructure company.

To obtain a free quote for the rental of an ATWS, either contact Schweizer Electronic directly on 01827 289996, or make contact with our partners using this link.

6. How does an ATWS and LOWS save money?

ATWS and LOWS save money in 3 ways:

a. Reducing the fines paid by the Infrastructure Company to Train Operating Companies for disrupting scheduled train services. This is because ATWS allows appropriate work to be carried out on a live railway.
b. Reduction in the number of protection staff required, particularly where a number of assisted lookouts are required to protect track workers on a complex track layout.
c. An increase in track worker productivity since the maintenance team is not waiting for short and unreliable possessions to carry out activities.

7. What is a permanent TWS?

A Track Warning System (TWS) can be fitted permanently to sections of the track.

These systems can provide 24/7 access to running rail for planned and unplanned maintenance activities. ATWS, SATWS and SCWS are most suitable for permanent TWS.

In the case of SCWS, they can be configured to begin an automatic start up cycle and operate at the press of a button without the need for protection staff.

8. How do your Level Crossings differ from the systems currently in operation in the UK?

As opposed to traditional relay technology, Schweizer Electronic’s Level Crossing system, Flex, uses standard electronic components and a modular design. This forms the basis of a range of Level Crossings from basic user work crossings to multi-barrier systems.

Standardization allows the systems to be manufactured and tested relatively quickly in our factory in Switzerland. ‘Plug and Play’ technology also reduces the amount of installation time onsite, and limits the disruption to train traffic.