{"id":19564,"date":"2025-11-25T09:12:21","date_gmt":"2025-11-25T08:12:21","guid":{"rendered":"https:\/\/www.darda.de\/?page_id=19564"},"modified":"2025-11-25T09:12:21","modified_gmt":"2025-11-25T08:12:21","slug":"construction-time-forecast","status":"publish","type":"page","link":"https:\/\/www.darda.de\/en\/knowledge\/construction-time-forecast","title":{"rendered":"Construction time forecast"},"content":{"rendered":"
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The construction time forecast describes the forward-looking determination of the duration and sequence of a project\u2014from demolition works<\/em> and gutting works<\/em> through deconstruction<\/em> in existing structures to rock excavation<\/em> and tunnel excavation<\/em>. In practice, it ties together methodology, experience, and concrete performance assumptions. Especially for construction methods with highly variable productivity\u2014such as controlled concrete demolition<\/em> using a concrete demolition shear<\/em> or non-explosive separation using a hydraulic splitter (wedge)<\/em>\u2014the quality of the construction time forecast determines schedule adherence, cost stability, and construction site safety<\/em>.<\/p>\n

Definition: What is meant by construction time forecast<\/h2>\n

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<\/em> method, available resources, and expected performance values.<\/p>\n

Methods and key figures in the construction time forecast<\/h2>\n

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<\/em>, rebar cutting<\/em>, demolition sorting, haulage logistics<\/em>) and third, consideration of risks and environmental conditions. For deconstruction<\/em>, product- and method-specific indicators are crucial\u2014for example, hourly removal rates with a concrete demolition shear<\/em> or the splitting progress with a hydraulic splitter (wedge)<\/em>\u2014because they directly influence the takt of downstream activities such as material handling, transport, or rebar processing.<\/p>\n

Approaches to determining construction time<\/h2>\n

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<\/em> trades, section-wise takts that reflect real construction logistics\u2014including equipment changes, setup times, and material removal<\/em>\u2014are recommended.<\/p>\n

Bottom-up planning<\/h3>\n

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<\/em> capacity, hydraulic power pack output, crane time).<\/p>\n

Top-down approach<\/h3>\n

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.<\/p>\n

4D-\/BIM-supported simulation<\/h3>\n

Geometry, construction states, and schedule are linked. For deconstruction<\/em> sections (e.g., slab fields), alternative sequences can be simulated and bottlenecks revealed early.<\/p>\n

Lean takt planning<\/h3>\n

Even takts per section increase predictability. Particularly effective when the performance of the tools used\u2014such as concrete demolition shear<\/em>, hydraulic demolition shear<\/em>, or Multi Cutters\u2014is stable and repeatable.<\/p>\n

Buffers, reserves, seasonal effects<\/h3>\n

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.<\/p>\n

Influence of tool and method selection<\/h2>\n

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.<\/p>\n

Concrete demolition shear in controlled concrete demolition<\/h3>\n

A concrete demolition shear<\/em> 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<\/em> improves the predictability of schedule progression. For fundamentals and constraints, see concrete demolition and deconstruction<\/a>.<\/p>\n

Hydraulic splitter (wedge) in non-explosive separation<\/h3>\n

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)<\/em> (Rock Splitters<\/a>), and the debris clearance<\/em> should be scheduled as separate activities.<\/p>\n

Hydraulic power packs and energy supply<\/h3>\n

Hydraulic power pack<\/em> 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<\/em> tools, including selecting appropriate hydraulic power units<\/a> for the intended number of tools.<\/p>\n

Combination shears, Multi Cutters, and steel shears<\/h3>\n

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.<\/p>\n

Tank cutters<\/h3>\n

For tank and vessel tank dismantling<\/em>, protection concepts, inerting, section sizes, and waste disposal logistics<\/em> influence the duration more strongly than pure cutting speed. These boundary conditions must be explicitly included in the construction time forecast.<\/p>\n

Set productivity metrics realistically<\/h2>\n

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.<\/p>\n