Explosive ordnance assessment for cable trenching and signalling systems

Technical assessment should begin as soon as cable alignments, chambers, crossings, signal foundations, signal box connections and construction stages are sufficiently defined. Early design stages can start with assessment of the historical evidence of ordnance. Before tendering and construction, route width, depth of ground disturbance, individual foundations and inaccessible areas must be addressed through suitable investigation or a clear follow-up measure.

Cable trenches, cable ducts, protective pipes, jointing and cable chambers, crossings, signals, axle counters, balise locations, switching buildings, earthing systems and temporary excavations must be considered. Each component has its own position and depth geometry. A general route assessment therefore replaces neither point-specific foundation investigation nor section-specific assessment of deep crossings.

Existing cables, cable troughs, rails, earthing systems, signals, masts, foundations and metal installations are recorded before method selection. They can obscure survey data while also providing useful comparison information. Sections that cannot be adequately surveyed are marked on the drawing. The assessment establishes when they become accessible and which additional investigation suits the planned ground disturbance.

This depends on trench depth, working width, ground conditions, surface, target object and interference. A suitable surface method may be sufficient for shallow, accessible sections. Deep crossings, chambers, signal foundations or areas outside the demonstrated investigation zone require their own point or depth investigation.

The launch and reception pits, bore path, design depth, diameter, drilling method and safety volume are considered as connected investigation areas with differing access conditions. Pits accessible from the surface may need different methods from the deep bore corridor. An assessment of the launch pit is not automatically extended to the entire underground path.

Explosive ordnance surveying during construction is considered where technically suitable for the planned ground disturbance. This may apply to trenches that become accessible only after demolition or cannot be adequately investigated beforehand because of existing cables, ballast, foundations or operational restrictions. Each working layer is surveyed and assessed by a specialist. Controlled excavation in layers and an additional visual inspection follow; these steps are repeated to the agreed base of excavation. Excavation layers, equipment use, stop points, responsibilities and reporting procedures are agreed before work begins. The conclusions remain limited to the working volume actually investigated.

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.

The documentation should bring together the alignment, chainage, working width, depth, chambers, crossings, individual foundations, methods used, survey and field conditions, findings, limitations and follow-up decisions. Changes to the cable route or signalling locations are checked against the documented investigation scope and recorded as a drawing revision.

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

Key factors are route length, the number of chambers and crossings, trench depth, individual foundations, access, possession windows, existing cables, track superstructure, methods required, data formats and documentation requirements. Additional depth investigations, repeat surveys or services during construction are considered separately where they fall outside the original scope.