Any civil construction project requires a stringent focus on safety, and this is particularly the case on road and rail projects where work is often done in close proximity to live traffic and in the presence of overhead lines. The common practice is to have a spotter who watches the machine and alerts the operator if they are in danger of hitting something. However, inattention by the spotter or miscommunication can result in human error.
One way to help mitigate this danger is to ensure that plant and machinery are fitted with height and slew limiters. We have excavators ranging from 5 tonne to 20 tonne that have the height and slew limiters fitted. A major safety feature of these is the Key Lockout which prevents operator error or over-ride, and this feature is required by some authorities (including rail asset owners). Standard OEMs do not have this feature.
The Sentinel Height Limiter from PRM Solutions allows us to set a maximum height limit for our excavator boom and, if the boom is at risk of exceeding that height, the operator is notified. If the boom continues to move towards the height limit, the boom-up solenoid is deactivated. This keeps machinery and operators safe when working near live overhead lines or within confined spaces. These limiters have predictive technology which allows them to take into consideration the speed of the boom, and the size and shape of the excavator bucket, and prevent overshoot.
The Slew Limiter works in a similar way but is designed to prevent the boom from travelling horizontally into a designated area. In essence, a ‘geo-fence’ is set up determining the limits of the plant’s working area. So where our excavator is working next to a live railway line or road, for example, the limiter prevents it from swinging into the traffic corridor.