Today's level crossing installations built in relay technology will be phased out and replaced by Alex who has a number of improvements compared to the older technology.
Trafikverket will purchase Alex as a frame agreement. When a specific Alex system is subordered the number of signals, barriers etc must be specified.
The main feature is of course warning road users of the passing train. Alex, however, has a number of improvements that are not available in the older technology:
- Improved protection against trespassing ("barrier skirts")
- Acoustic signals adjusted to the ambient needs
- Log function, such as a blown out lamp
Trafikverket will secure the availability to the product by signing a long term management contract with the system provider. The aim is throughout the entire technical life, secure access to the product, including spare parts
Alex control equipment is built into cabinets where each function has its specific place:
- Power supply and climate control
- IP network
- Control system for signals and barriers
- Track circuits
- Interface with other systems
The Alex system includes also external objects such as barrier machines, barriers, optical signals and so on. The supplier decides how these should be connected to the control system. Trafikverket consider these interfaces as internal and will not specify them. Interfaces to other systems such as signal boxes, however, will be specified in detail.
Alex means Automatic Level Crossing. "Level Crossing" usually abbreviated as "LX" which has led to the name Alex.
Today's relay-based systems were developed at a time when it was customary to build everything in house, by assembling specific components. This approach, however, requires a lot of responsibility in detail. If a component is no longer possible to purchase on the market, it must be replaced with another component. This requires a safety assessment, a time-consuming and expensive process.When a component finally is replaced, it may be time for the next
To build complex systems with discrete components is a skill that increasingly fewer people master. A computerized control system is today a more obvious choice and the railroad must also take this step. There is also a market where systems can be bought on the shelf, even if they initially have to be adapted to Swedish conditions.