Explosive ordnance survey for tunnel construction and underpasses

Specialist assessment should begin as soon as portal areas, ramps, open excavations, shafts, shoring alignments and proposed foundations can be identified. For tendering, existing indications of suspected ordnance, construction methods, phases, intervention depths and zones accessible only after demolition should be shown on the drawings. This enables reliable determination of investigation requirements by element, depth and construction stage.

Portal approach areas, ramp troughs, open excavations, diaphragm or sheet-pile walls, bored piles, anchors, launch and reception shafts, operational buildings, drainage and escape structures affect the ground in different ways. An area survey of the approach does not automatically cover deep walls, piles or inclined anchors. Each working volume is described by location, depth, direction and installation method.

For cut-and-cover construction, the focus is on the excavation, shoring, ramps and phased excavation work. For mined or mechanised tunnelling, particular attention is paid to portals, shafts, surface structures, ground investigations and the volumes actually affected by the construction method. The explosive ordnance investigation is therefore not applied to the whole tunnel as a blanket conclusion, but is tied to the specific accessible areas relevant to ground disturbance.

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.

Effort, duration and cost depend on construction methods, areas, depths, wall alignments, pile and anchor geometries and the surrounding technical installations. Construction phases, equipment access, dewatering, traffic management and the required documentation affect the sequence. New shaft locations, replacement piles or altered anchors may require additional investigation. Structural and shoring drawings, point schedules, sections and the construction sequence are needed for costing.

If existing structures, shoring, utilities or the construction stage prevent complete preliminary investigation, the technical suitability of explosive ordnance detection during construction is assessed. Each working layer is surveyed and evaluated using technical methods before controlled removal in layers with supplementary visual inspection. The steps are repeated down to the agreed excavation base. Excavation layers, equipment use, hold points, lines of instruction and documentation are established before work starts. Necessary investigations and protective measures are also planned before ground disturbance during breaking out or demolition; unrecorded areas remain unresolved.

A clear structure and chainage reference is required, together with assignment to the portal, ramp, excavation, wall, pile, anchor or shaft, the relevant drawing revision, documented investigation geometry, methods used, technical limitations, anomalies, findings and subsequent decisions. For staged construction, partial handovers and areas accessible later must remain capable of being updated.

Helpful documents include site and structural drawings, tunnel alignment, portal and ramp geometries, excavation and shoring drawings, pile and anchor schedules, shafts, construction methods, phases, ground and groundwater data, utility drawings, historical assessments, existing survey reports and the required decision date. An early design is also suitable if options and binding working volumes are clearly marked.

Information and requirements from authorities are supplied with their date, complete appendices and geographical scope. In Germany, the competent ordnance disposal service, local public-order authority and, where relevant, building-control authority are identified for the project location; outside Germany, local responsibilities apply.