The construction time forecast describes the forward-looking determination of the duration and sequence of a project—from demolition works and gutting works through deconstruction in existing structures to rock excavation and tunnel excavation. In practice, it ties together methodology, experience, and concrete performance assumptions. Especially for construction methods with highly variable productivity—such as controlled concrete demolition using a concrete demolition shear or non-explosive separation using a hydraulic splitter (wedge)—the quality of the construction time forecast determines schedule adherence, cost stability, and construction site safety.
Definition: What is meant by construction time forecast
A construction time forecast is the systematic prediction of the expected project duration including milestones, buffers, and dependencies. It combines capacities, equipment deployment, takt sequences, logistics, boundary conditions (e.g., approvals, weather, emission limits) as well as risks. The goal is a robust schedule that realistically reflects the chosen construction or deconstruction method, available resources, and expected performance values.
Methods and key figures in the construction time forecast
A robust construction time forecast rests on three pillars: first, methodological structuring (e.g., activity chains, takt planning, critical path), second, suitable performance metrics for work steps (e.g., concrete separation/cutting, rebar cutting, demolition sorting, haulage logistics) and third, consideration of risks and environmental conditions. For deconstruction, product- and method-specific indicators are crucial—for example, hourly removal rates with a concrete demolition shear or the splitting progress with a hydraulic splitter (wedge)—because they directly influence the takt of downstream activities such as material handling, transport, or rebar processing.
Approaches to determining construction time
Depending on planning depth, different approaches are used. In early phases, benchmarks from similar projects dominate. With increasing detail, assumptions are refined: activity lists with defined performance rates, resource allocation, and buffer logic are created. For demolition and deconstruction trades, section-wise takts that reflect real construction logistics—including equipment changes, setup times, and material removal—are recommended.
Bottom-up planning
Work activities are captured in small steps, assigned performance rates, and aggregated into sections. This makes it possible to identify bottlenecks (e.g., haulage logistics capacity, hydraulic power pack output, crane time).
Top-down approach
Experience-based values define overall durations that are then calibrated through targeted detailing (e.g., separation technique, number of devices). Useful for feasibility studies or schedule framing.
4D-/BIM-supported simulation
Geometry, construction states, and schedule are linked. For deconstruction sections (e.g., slab fields), alternative sequences can be simulated and bottlenecks revealed early.
Lean takt planning
Even takts per section increase predictability. Particularly effective when the performance of the tools used—such as concrete demolition shear, hydraulic demolition shear, or Multi Cutters—is stable and repeatable.
Buffers, reserves, seasonal effects
Time reserves account for uncertainties such as weather, approvals, demolition separation, or unknown reinforcement densities. Seasonal windows and shift models (e.g., extended working hours with noise-reduced methods) are explicitly planned.
Influence of tool and method selection
The choice of tools significantly shapes construction time. Methods with low vibrations and precise demolition separation are often approval-friendly and increase schedule stability. At the same time, performance values vary depending on material, component geometry, and accessibility.
Concrete demolition shear in controlled concrete demolition
A concrete demolition shear enables targeted removal of concrete components with reduced vibrations. The forecast should consider component thicknesses, reinforcement content, gripping and shearing paths, protective measures (dust suppression, water spray system), and the takt of subsequent sorting. A uniform material removal improves the predictability of schedule progression. For fundamentals and constraints, see concrete demolition and deconstruction.
Hydraulic splitter (wedge) in non-explosive separation
During splitting, drilling pattern, access for splitting, stress-induced cracks, and varying rock or concrete qualities affect progress. Drilling times, the cycle times of the hydraulic splitter (wedge) (Rock Splitters), and the debris clearance should be scheduled as separate activities.
Hydraulic power packs and energy supply
Hydraulic power pack performance determines takt and parallelization. The forecast must account for hose line routing, hydraulic connection changes, refilling and maintenance windows, and the supply of multiple attachment tools, including selecting appropriate hydraulic power units for the intended number of tools.
Combination shears, Multi Cutters, and steel shears
Cutting structural steel sections, beams, or cable trays varies with cross-section and accessibility. Setup times during tool changes and positioning act as buffer or delay factors.
Tank cutters
For tank and vessel tank dismantling, protection concepts, inerting, section sizes, and waste disposal logistics influence the duration more strongly than pure cutting speed. These boundary conditions must be explicitly included in the construction time forecast.
Set productivity metrics realistically
Performance values should be cross-checked using reference projects, trial fields, or manufacturer information on the device type and adapted to local conditions. Conservative assumptions on critical paths increase schedule reliability.
- Material parameters: concrete strengths (e.g., concrete compressive strength class), reinforcement ratio, aggregates, natural rock fracturing.
- Component geometry: thickness, position, cut edges, separation joints, accessibility, and working heights.
- Logistics: routes, intermediate material storage, sorting areas, haulage logistics frequency, cranes and lifting devices.
- Occupational safety and emissions: noise emission windows, dust suppression, low vibration levels, safety distances.
- Personnel deployment: team sizes, shift models, learning curves, training on special equipment technology.
Forecast by application areas
Depending on the application area, the decisive influencing factors differ. The following guidelines help calibrate the construction time forecast.
Concrete demolition and special deconstruction
The focus is safe sequencing: structural stabilization, separation joints, load-free areas, sectional deconstruction. A concrete demolition shear and hydraulic demolition shear deliver predictable progress in consistent takt sequences. For special deconstruction (e.g., in sensitive neighborhoods), low-vibration methods with a hydraulic splitter (wedge) increase schedule robustness through fewer closures and more reliable approvals.
Gutting and cutting
Here, dismantling and sorting takts dominate. Multi Cutters and steel shears determine the speed of cutting out fit-outs, cable routes, and steel components. The forecast should consider material mix, dismantling sequence, sort purity, and travel times.
Rock excavation and tunnel construction
In rock, productivity varies with geology, water flow, and fracturing. Rock splitting cycles with a hydraulic splitter (wedge) become predictable and repeatable when drilling pattern, splitting sequence, and material removal are precisely takt-planned. In tunnel construction, cross-section, tunnel face support, and tunnel ventilation are time-determinant.
Natural stone extraction
Extraction benefits from uniform splitting patterns and a robust logistics chain for blocks. Construction time forecasts consider yield, block sizes, anchoring and lifting operations, and weather windows.
Special operations
Special conditions (e.g., work under operation, restricted access, night windows) require finely granular takts and redundant equipment concepts. Here, a conservative buffer strategy increases schedule reliability.
Systematically mapping risks and uncertainties
Risks are identified, quantified, and backed with schedule reserves. Typical uncertainties involve exploration depth, utility finds, regulatory requirements, weather, equipment downtime, and material fluctuations. Scenario comparisons (optimistic, realistic, conservative) increase the forecast’s significance.
Permits, emission control, and neighborhood
Requirements for noise, vibrations, and dust influence working hours and methods. Low-immission methods—such as splitting of concrete or rock with a hydraulic splitter (wedge) and thus non-explosive rock removal—can extend time windows. Planned measurements, approvals, and acceptances are scheduled as separate activities. Notes here are general and do not replace case-by-case review.
Data basis and documentation
Reliable forecasts are based on solid data: plans, reinforcement data, material tests, trial fields, access and logistics concepts. Clean documentation of assumptions (equipment performance, team sizes, takts, buffers) facilitates progress control and later adjustments.
Practical advice for process and schedule planning
- Form sections along logistics axes and lifting points.
- Early coordination of interfaces (disposal, transport, crane logistics) with focus on waste disposal logistics.
- Plan equipment capacities so that material removal never becomes the bottleneck.
- Set changeover and setup times realistically; provide reserves for tool changes.
- Takt control with clear intermediate targets; daily actual/plan comparisons.
- Prioritize low-emission methods for noise-sensitive projects (noise control measures, low vibration levels).
- Plan trial fields to calibrate performance assumptions (field trials/tests).
Measurable quality criteria of a construction time forecast
- Completeness: All essential activities, dependencies, and interfaces are captured.
- Correctness: Performance rates are validated and adapted to local conditions.
- Transparency: Assumptions, buffers, and risks are documented in a traceable manner.
- Adaptability: Updating based on actual values is provided for.
- Legal and framework conditions: Time windows from requirements and neighborhood are considered.
The role of Darda GmbH in the context of the construction time forecast
Darda GmbH stands for tools and power packs used in deconstruction, gutting works, as well as in rock and tunnel construction. For the construction time forecast this means: performance values of the concrete demolition shear, hydraulic splitter (wedge), hydraulic demolition shear, Multi Cutters, steel shear, cutting torch (for tank dismantling), hydraulic power pack, and hydraulic splitter (wedge) flow as product-specific assumptions into the takt planning. The key is to calibrate these values project-specifically and integrate them with logistics, personnel, and regulatory requirements into a coherent time model.