The TSP Projects Level Crossings team are a very busy department. Ensuring safety is their top priority and they draw on industry experience, new technologies and innovation to ensure they are always ahead of the game. We’re highlighting a series of the team’s key learnings in our regular Tech Talks.

Primary Obstacle Detectors

The TSP Projects in-house Level Crossings Team have had no less than 36 MCB-OD level crossing (Manually Controlled Barriers – Obstacle Detector) designs installed and successfully commissioned in the last 3 years.

This type of level crossing is the latest development in monitoring systems and is controlled by a combination of two systems; RADAR and LIDAR. In effect these systems are the Signallers eyes on the ground and, thanks to their independent scanning capabilities, they confirm that the crossing is clear once the barriers have lowered. This ‘LX Tech Talk’ will concentrate on the RADAR aspect i.e. the Primary Obstacle Detector (POD) system.

How does it work?

The POD unit, which is shown in the foreground of the photograph, is often referred to as a giant ‘tic-tac’ but the smooth housing actually shields the RADAR unit from the weather (and vandalism!). Once activated, the RADAR spins at one revolution per second and, in simple terms, the barriers lower and the RADAR then checks for obstructions within the level crossing area. If none are detected, the crossing is deemed ‘clear’ and the train can proceed at full linespeed.

In order to scan the crossing, the POD unit needs to confirm it is scanning the correct area. It does this by cross referencing the positions of 3 POD ‘reflectors’ (the triangular shape in the background of the photograph) with a set of pre-programmed coordinates. If the positions of the reflectors match the coordinates, then the POD unit knows it is scanning the correct area. If they do not match, the lowered barriers will rise and the train will be held at a protecting signal on the approach to the crossing. The same happens if an object is identified within the crossing area.

Did you know? The POD Reflectors bounce back the RADAR signals due to their shape – they are not conventional mirrors!

Interested in finding out more about our Level Crossings team? Click here