Explosive ordnance detection for motorway projects

Specialist assessment should begin as soon as the route corridor, construction sections and proposed ground interventions are sufficiently clear. For new construction, widening, full-depth renewal, interchanges, civil engineering structures, drainage or noise barriers, suspected ordnance, working width, depths, traffic phases and accessible areas must be brought together before tendering. Historical assessment, area surveys, deep point-specific investigations and construction-stage measures can then be distinguished in good time.

Carriageways and central reservations, hard shoulders, slopes, drainage, cable routes, interchanges, bridge areas, retaining walls, noise barrier foundations, service areas and site establishment areas affect the ground in different ways. Area measurements on an accessible traffic surface do not automatically address deep pile, sheet-pile, mast or drilling points. Each working volume is therefore described by location, width, depth, construction method and planned construction stage.

The work is organised by construction section, traffic management, accessible working area and the date of subsequent earthworks. Surveying, equipment access, protection zones, data checks and handover must be agreed before each window begins. Areas accessible only after demolition, diversion or construction of temporary arrangements are assigned their own investigation date. A short time window does not change the required survey and documentation quality.

Selection depends on suspected ordnance, target object, surface, ground, technical interference and required depth. Magnetometry, TDEM and ground-penetrating radar detect different physical properties and are not freely interchangeable. For deep foundation, shoring and drilling points, it is checked whether the required depth can be covered from the surface or whether a deep-ground or borehole survey is needed. For areas that cannot be surveyed adequately, access and suitable further investigations are established. Where explosive ordnance detection during construction is suitable, each layer is surveyed using technical methods and evaluated by specialists. Controlled removal in layers and supplementary visual inspection follow; the steps are repeated down to the agreed excavation base. Simply watching the excavator is insufficient.

These subprojects have their own foundation and working volumes. Abutments, piers, piles, ramps, retaining walls, masts and noise barrier alignments are considered by coordinates, element geometry, target depth and installation method. Near-surface approach areas and deep point-specific ground interventions are documented separately.

Helpful documents include site and route drawings with kilometre or chainage references, construction-section boundaries, traffic phases, cross-sections, planned intervention depths, borehole and foundation-point schedules, drainage and utility drawings, historical assessments, authority correspondence, ground investigation documents and existing survey or clearance reports. Preliminary documents can be used if their revision, assumptions and unresolved structural geometries are clearly identified.

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 established for the project location. Outside Germany, the locally competent bodies are identified through coordination.

Such areas are not presented as having no anomalies or as having been investigated along with other areas. Documentation shows their location, the reason for the limitation and the required follow-up measure. Necessary investigations and protective measures are specified before ground disturbance during demolition. Depending on the ground intervention and survey conditions, the suitability of measurements in areas accessible later, deep-ground surveys, specialist exposure or explosive ordnance detection during construction is assessed. Conclusions remain limited to the area and depth actually investigated and the documented construction stage.

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.

Relevant factors are section lengths and widths, construction phases, surfaces, accessibility, existing utilities and installations, the number and depth of foundation or drilling points, required methods, traffic and closure windows, surveying effort, data volume, investigation of anomalies and the documentation requested. Reliable costing therefore requires an itemised quantity and geometry schedule rather than a blanket figure in route kilometres.