Explosive ordnance investigation for railway power and overhead line installations

It becomes relevant when mast foundations, gantries, switching or feeder installations, cable routes, earthing installations, excavations or demolition affect ground with suspected ordnance or ground that has not been adequately assessed. The technical assessment should be complete before tendering and, at the latest, before the relevant foundation or cable installation is constructed.

Current site drawings are required showing the railway line, track, kilometre reference or chainage, mast or point numbers, coordinates, foundation type, dimensions, design depth, construction or installation method and existing utilities. Overhead line, earthing and cable drawings, ground investigation data, historical assessments, previous survey reports, construction time windows and the required records are also helpful.

Official information and requirements are included with complete appendices, dates and spatial scope. In Germany, the relevant ordnance disposal service and local public order authority are identified for the project location; operational switching and work authorisations remain separate processes. Outside Germany, coordination is with the authorities responsible locally.

Not automatically. A mast foundation, gantry support or deep cable structure affects a defined point and depth volume. A near-surface survey can assess the surroundings but covers the entire foundation geometry only if the method, depth and spatial coverage demonstrably support that conclusion. A separate depth or borehole investigation is often required.

Metal installations, return-current and earthing systems, cables, masts, reinforcement and operating electrical equipment can alter the magnetic or electromagnetic survey environment. The effects depend on the method and operating conditions. Known installations, possible operational isolations, survey distances and alternative investigation approaches are therefore considered when selecting the method.

Each point receives a unique identifier with the railway line, track, chainage or coordinates, foundation type, design depth and drawing revision. Investigation depth, survey conditions, anomalies, limitations and follow-up measures are recorded for each point. A status list links individual points to the overall project and shows which locations have been investigated, remain outstanding, have been relocated or have been added.

The point is not automatically classified as being without anomalies. First, the assessment establishes whether revised drilling or survey geometry, an alternative point, another construction stage or a different method can still cover the required working volume. Any remaining gap is marked on the drawing and in the point status and assigned a specific follow-up measure before ground disturbance.

The suitability of explosive ordnance surveying during construction is assessed for cable trenches, demolition excavations and switching installation areas. Each working layer is surveyed and assessed by a specialist before removal. Controlled excavation in layers and an additional visual inspection follow; these steps are repeated to the agreed base of excavation. Excavation layers, working areas, equipment operation, stop points, channels for issuing instructions and documentation are agreed before work begins. For deep mast or pile foundations, this does not automatically replace the required point-specific depth investigation.

If an unexpected suspicious object is found, stop work. Do not touch, move or uncover it further. Leave the immediate area and warn others without putting yourself at risk. In Germany, notify the police on 110; outside Germany, use the local emergency reporting procedure. The competent authorities determine what happens next; a project enquiry does not replace reporting the find.

Key factors are the number, location and depth of mast and foundation points, cable route lengths, foundation and construction methods, existing utilities and installations, interference, access, possessions and electrical switching windows, surveying required, number of mobilisations, data quality and documentation requirements. A reliable estimate requires a consistent point list and set of drawings.