The structure gauge clearance describes the space that must be kept free around travel paths, traffic and working areas so that structures, vehicles, equipment and loads can be operated without collisions and moved safely. In the context of demolition works, special demolition, rock excavation and tunnel construction, the structure gauge clearance is a central planning and execution criterion: It governs cross-sections, equipment deployment, site setup, construction logistics and demolition sequences. Anyone working with concrete pulverizers or rock and concrete splitters must consistently protect the clearance—both in existing installations and in temporary construction states.
Definition: What is meant by structure gauge clearance
Structure gauge clearance is the geometrically defined clearance along a traffic or working route. It includes clear width and height, necessary safety distances and—depending on the application—additional allowances for vibrations, settlements, deflections, manufacturing tolerances and construction states. In practice, a distinction is made between:
- the standard structure gauge clearance for permanent operation (e.g., rail, road or tunnel cross-sections),
- the working structure gauge clearance for assembly, demolition and transport processes,
- the profile clearance cut, i.e., the sum of all measures that keep the profile clear.
For existing facilities, structure gauge clearances are described by standards and guidelines. In construction states, they are defined project-specifically. They serve as a binding basis for clash detection, safety concepts, construction logistics, equipment allocation and the forward-looking planning of demolition steps—such as when using concrete pulverizers, rock wedge splitters or combination shears.
Importance of structure gauge clearance in planning and execution
The structure gauge clearance translates technical requirements into clear geometric specifications. It determines which equipment configurations can be used, which auxiliary structures are required and how demolition or rock-breaking works are sequenced. Especially in concrete demolition and special demolition as well as in rock excavation and tunnel construction, a precisely defined clearance provides the basis for safe routes, collision-free crane and transport moves and the positioning of hydraulic power units. This makes it possible, for example, to select concrete pulverizers with adapted reach, to plan rock and concrete splitters in tight cross-sections and to size temporary protective scaffolds without undershooting the working structure gauge clearance.
Classification by application fields: Rail, road, tunnel and existing structures
Depending on the environment, the objectives and design of the structure gauge clearance differ. The common denominator is clear dimensions, documented boundary conditions and reconciliation with equipment data and load cases.
Rail-adjacent areas
In rail-adjacent zones, the structure gauge clearance is shaped by operational requirements: distance to track centerlines, overhead lines, signals and structure edges. When dismantling railway bridges or abutments with concrete pulverizers and steel shears, profile violations by components or equipment must be excluded. Demolition pieces are separated so that they do not enter the operating space; rock and concrete splitters enable controlled release of massive components within narrow cross-sections.
Road and civil engineering
On roads and under bridges, clear heights and widths apply for vehicles, exclusion and protection zones. During strip-out and cutting of superstructures, during tank cutting or when working with Multi Cutters, temporary protective enclosures and scaffolds must respect the drive-through clearance. Material flow and traffic management are coordinated accordingly.
Tunnels and caverns
In tunnel construction, the structure gauge clearance defines the cross-section to be kept free for construction and operation. It takes into account lining states, shotcrete allowances, drainage and cable routes. When installing and dismantling linings or when rock is released with rock wedge splitters, cross-section increases due to overbreak and protrusions must be limited so that transport vehicles and escape routes remain fully usable.
Surveying and modeling of the structure gauge clearance
Reliable clearance planning begins with an as-built survey: geometry, installations, tolerances and dynamic influences are recorded and—ideally—combined in a digital model. From this, working areas for concrete pulverizers, combination shears or cutting torches can be derived precisely.
Typical work steps
- As-built surveying (e.g., by total station or laser scan) and derivation of clear dimensions.
- Definition of standard and working structure gauge clearances for all construction states.
- Clash checks for equipment, booms, grapples and hose routing.
- Definition of protective measures (impact panels, safety nets, protective enclosures).
- Documentation and release for execution.
Working structure gauge clearance and equipment deployment
The working structure gauge clearance supplements the standard clearance with the movement spaces of equipment, the slewing areas of booms and the escape path of demolition pieces. It is particularly relevant for:
- Concrete pulverizers: reach, jaw opening and slewing radii determine distance to structure edges and scaffolds.
- Rock and concrete splitters: equipment dimensions, splitting forces and wedge travel influence required working spaces in shafts and drifts.
- Combination shears, Multi Cutters, steel shears and cutting torches: cut lines, gripping positions and retreat options must be planned in conformity with the clearance.
- Hydraulic power units: setup areas, hose routes and ventilation are to be chosen so that escape and traffic routes remain clear.
Practical rules
- Moving parts receive an additional safety distance as a dynamic allowance.
- Hose and cable management prevents profile violations due to sag.
- Select the demolition sequence so that the clearance increases step by step and does not narrow.
In concrete demolition and special demolition, an approach that first relieves and preloads components and then removes them in a controlled manner with concrete pulverizers has proven effective. In confined conditions, rock wedge splitters and concrete splitters enable particularly clearance-true component breakup, as they work without vibrations and without large cantilevers.
Temporary clearances in construction states
During the construction phase, boundary conditions often differ from the final state: scaffolds, auxiliary beams, construction power supply, ventilation, exhaust routing and fire protection take up space. A temporary structure gauge clearance defines which minimum dimensions are necessary for safe operation despite these installations.
Important differences from the final clearance
- larger safety allowances for assembly and transport operations,
- differing traffic and escape routes with separate marking,
- additional restrictions for sparks, dust and media lines during cutting.
During strip-out and cutting, the temporary clearance is the basis for arranging extraction and protective enclosures without compromising traffic and escape routes.
Protection and safety measures
Profile clearance cut means not only geometry, but also protection against uncontrolled advances, falling parts or impact. When working with concrete pulverizers, steel shears and cutting torches, the following measures are typically combined:
- Mechanical protection (impact panels, safety nets, underpinning systems),
- Catch and guide ropes for demolition pieces in vertical shafts,
- Cutting and splitting sequences with defined retreat movements,
- Dust and spark shielding, especially in tunnels and enclosed spaces.
In rock excavation and tunnel construction, controlled splitting techniques help minimize clearance exceedances due to overbreak while protecting adjacent structures.
Measurement and test methods
To ensure that the structure gauge clearance is reliably maintained, pragmatic checks during the construction process are necessary:
- Profile gauges or templates for critical cross-sections,
- Laser-scan spot checks for progress control,
- Clearance test runs or functional runs in construction states (where permitted),
- Photo documentation and comparison with planning status.
The results feed into ongoing clash detection. Deviations are corrected with adapted demolition or splitting sequences.
Legal and normative aspects
The design of structure gauge clearances is based on applicable technical regulations and official requirements. Depending on the field of application (rail, road, tunnel, industry), different foundations apply. The information in this article is general in nature and does not replace a project-specific review. The binding basis is always the applicable regulations, approvals and conditions of the competent authorities.
Typical application cases
Bridge dismantling over traffic routes
Demolition with concrete pulverizers and steel shears is carried out with temporary protective superstructures. The structure gauge clearance under the bridge remains free through protective scaffolds and defined hoisting and slewing movements. Demolition pieces are lifted out along secured load paths.
Tunnel cross-section adaptation
When widening existing tunnels, a sequence of pre-cut, controlled splitting with rock wedge splitters and subsequent profile trimming helps. In this way, the profile clearance cut is continuously demonstrated and construction traffic can be maintained in parallel.
Strip-out in existing buildings
In confined shafts and corridors, the working structure gauge clearance determines the use of concrete pulverizers and Multi Cutters. Hydraulic power packs are positioned outside the movement spaces, hose routes are secured and escape routes are kept clear at all times.
Planning guide for clearance-compliant dismantling
- Equipment selection with profile check: reaches, jaw openings, slewing and retreat spaces.
- Demolition and splitting sequence: from inside to outside, from top to bottom, component-oriented.
- Protection concept: mechanical protection, dust routing, spark shielding, emergency lighting.
- Logistics: material flow, intermediate storage, transport within the clearance.
- Releases: documented clearance checks before each construction phase.
Common sources of error and countermeasures
- Underestimated hose and cable bend radii: Use support and guiding systems, avoid sag.
- Overlong components at lift-off: Pre-segmentation with concrete pulverizers or splitting technology to reduce slewing envelopes.
- Missing dynamic allowances: Plan safety allowances for movements and vibrations.
- Unclear definition of construction states: Define, mark and document the temporary clearance for each phase.
Documentation and communication
Well-documented structure gauge clearance improves safety, quality and schedule reliability. Plans, sketches, test protocols and photo documentation are just as much a part of this as team briefings and clear markings on site. Operators working with concrete pulverizers, rock and concrete splitters or combination shears thus receive clear guardrails for day-to-day practice.