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UK Barrier Crossings

photograph of a full barrier crossing with two gates


There are quite a number of different types of level crossings used in the UK. These include gated crossings either open and shut by a railway employee or operated from a signal box. Ungated crossings with flashing lights. Automatic half barrier crossings, these have barriers stretching half way across the road on the approach side. Full size ones are activated by the approach of a train. There are also full barrier crossings. Gated crossings still remain in use to this day.

photo of a full barrier level crossing with four gates
photograph of an automatic half barrier crossing
photo of a gated level crossing



We now have a range of boards to operate working models of all these types of level crossings. Our boards can either be operated manually with a switch or automatically with train detectors. The train detectors may be either reed switches or IRDOT-1 infra red detectors. Crossing controllers are available with either 2 or 4 sets of lights. A set of lights consisting of outputs to operate 1 amber and 2 red (flashing) LEDs. Different boards are available with either an option for operating the barriers by a servo motor or by a contact to allow devices such as a slow motion point motor or memory wire to be used to operate the crossings.

UK Crossing 2L

This consists of 2 sets of lights and an on off contact.

UK Crossing 4L

This provides controls for four sets of lights and an on off contact.

UK Crossing 2L Servo

This provides controls for two sets of lights and two servo motors.

UK Crossing 4L Servo

This provides controls for four sets of lights and two servo motors.

UK Crossing 4L Servo Faller

This provides controls for four sets of lights and two servo motors plus contacts for operating an electromagnet to stop faller cars.

These boards are also available without the preliminary amber light for "overseas" railways. These are labelled grade crossing.


diagram showing connections to wig wag boards for a barrier level crossing controller

Automatic half barrier crossings

These are straight forward to operate with our boards.

Full Barrier Crossings

With a full barrier crossing there are usually four barriers. Sometimes for narrow roads just 2 barriers are used in which case the above boards are fine on their own. For crossings with 4 barriers there is a terminal, labelled X, to activate a dual servo board. This dual servo board allows an extra 2 barriers (the exit barriers) to be operated by servo motors. Full size crossings operate in two ways, either all four barriers lower together, (this seems to happen with barriers under the sight and control of signal boxes) or the barriers on the exit side of the road will not lower until the entry barriers have lowered. This is to prevent cars becoming trapped on the railway lines with all barriers lowered.

Terminal X is wired to both the S terminals on the Dual Servo controller boards.

Gated Crossings

These may have either two or four gates. When two gates are used the gates need to open and close one at a time because if they both moved together they would collide. We have provided this option on the board. In the case of four gates they will all open and close together. It is possible to operate four gates with two servo motors if each motor moves two gates. A less mechanically fiddly option is to use the X terminal tooperate a Dual Servo controller, this has the advantage that the positions of all the gates can be set individually with there push buttons.

Wiring for an automatic single track crossing

diagram showing location of detectors for a single track automatic half barrier level crossing (ahb)

This wiring applies to all the crossing boards. The boards use detectors at the approach and exit to the crossing. These are labelled D1 and D2 to correspond to rhe terminals, the detectors may be reed switches or IRDOT-1 infra red detectors. Operation is slightly different for both as the IRDOT-1 detects the whole of the train whilst the reeds can only detect where the magnet is fixed along the train.

Operation with IRDOT-1 detectors

The train may approach from either direction. As soon as soon as the front of the train is detected by the first detector (which could be either D1 or D2 depending upon which direction it is travelling in)the crossing sequence will start with amber being lit for seconds then the red lights flashing and the barriers lowering. When the train reaches and clears the second (exit) detector the lights will stop flashing and the barriers will reopen. It is designed for the train to clear the exit detector so that there is no possibility of a long train still being across the crossing.

Operation with reed and magnet

As the crossing will start amber when the magnet reaches the first reed switch and raise the barriers when the magnet reaches the second reed switch then some thought needs to be given to where the reeds are best located particuarly if the trains are of significantly different lengths. This problem is overcome by the IRDOT-1 detectors.

Wiring for an automatic double track crossing

diagram showing location of detectors for a double track level ctossing


This works in the same manner as the single track wiring. Trains can run in either direction on each line. The crossing controller will continue flashing if a second train reaches the crossing before the first has left until both trains have left the crossing.

More than 2 tracks

If lines converge at the crossing then a detector can be located on each converging track and wired into the terminal. If there are triple or quadruple tracks across the crossing then it would be possible to have detectors connecting to D1 and D2 on both parallal lines. This would work fine unless two trains arrived on both of these tracks at the same time. This would confuse the crossing controller board. If this is likely to happen then the UK Crossing 2L board can be wired to detectors on the third and possibly fourth tracks. Its contact can then be wired to operate the SW terminal on the level crossing controller connected to the lights and barriers or gates.

diagram for double track level crossing showing location of detectors for a converging line

The wiring berween the IRDOT-1 infra red detectors and the Barrier level crossing controller plus wieing connections to the power supply show the simplicity of wiring model railway level crossings

The diagram shows how 2 IRDOT-1s are wired to the D1 and D2 terminals of the crossing control board and how all three boards are wired to a power supply

Servo motor adjustments

These are very similar to the Dual Servo motor controller. Each Servo has three push button switches used for its initial setup.The easiest way to adjust the servo motors position is to wire a switch to connect the SW terminal to the 0 terminal. With the switch closed the red lights will flash and the adjust1 and adjust2 push buttons can be used to set the first barrier to its lowered position. With the switch opened the push buttons are used to set the raised position of the barriers. There is a further push button which sets the speed the barriers move.

Future plans for crossings

We plan to provide models of working gates and barriers and have a trial 3D printed OO scale automatic half barrier. This should be ready for sale in October. We are also developing the (wig wag) boards which display the amber and 2 red flashing lights to the motorist.

More information about full size crossings

"Level crossings" ISBN 978-0-7110-3308-5 published by Ian Allan is a very informative book and gives a detailed history of the development of level crossings.