Temporary Works Design

We undertake temporary works design with particular specialist knowledge in the field of what we call sub-structure temporary works. According to BS 5975:2019, temporary works provide an engineered solution which supports or protects either a pre-existing structure or the permanent works during construction, or supports plant and/or equipment, or the vertical / side-slopes of an excavation during construction operations or to provide access to site or areas of the site. Temporary works are concerned with the control of stability, strength, deflection, fatigue, geotechnical effects and hydraulic effects within defined limits.

Temporary works can be considered to include, but is not limited to:

1. support or protection of a pre-existing structure or permanent works during construction, demolition or modification
2. provide stability to the permanent works during construction, pre-weakening or demolition 
3. provision of site security, or provision of access to the site or workplace or segregation of pedestrians & vehicles 
4. supporting or restraining plant, materials or equipment, including stability of water-borne craft
5. stability of slopes or earthworks in temporary condition or supports to the side or soffit of  excavations or supports/diversions of watercourses to facilitate construction operations
6. provision of safe work activity platforms on land or over water (e.g. jetties, scaffolding, edge protection)
7. measures of control for noise, dust, debris, fume, air quality, groundwater or any site discharges during construction or demolition (e.g. screens, bunds, de-watering, demolition debris)
8. providing protection or support to services
9. testing facilities such as pressure testing pipes, pile testing, pre-demolition floor load capacity testing, etc

Sub-structure temporary works could be considered as a sub-set of the broader discipline. Temporary works design that we normally undertake:

• Deep excavation support:
  • Diaphragm walls
  • Secant /contiguous / tangent pile walls
  • Kingpost walls
  • Sheet pile walls
  • Caissons and shafts
  • Ground anchors
  • Internal propping
  • Trench stability
  • Cofferdams
  • Ground freezing
  • Grouting
  • Deep soil mixing as temporary excavation support
• Temporary foundations:
  • Tower crane foundations
  • Thrust blocks
  • Temporary piles for lateral support
  • Temporary vertical loading to pre-existing structures
  • Re-use of foundations for temporary works considerations
• Slope stability
  • Temporary cuttings
  • Diversion embankments
  • Haul route embankments
• Temporary dewatering
  • Temporary excavations
  • Cofferdam drainage
  • Temporary surface water drainage
  • Temporary groundwater lowering
  • Grouting for groundwater control
• Temporary platforms
  • Construction platforms for heavy plant (piling rigs, mobile cranes)
  • Loading gantries
  • Haul roads
  • Reinforced soil embankments for temporary applications
• Other structures
  • Piling gates
  • Pontoon / jetty stability assessment
  • Thrust bores
  • Launch / reception pits for tunnelling activities
  • Jacking / thrust assemblies
  • Trench boxes / proprietary earth retention systems
  • Pile load test frames

The way we like to think about it is that the great thing about temporary works design is that it’s engineering in its most raw form. Imagine the outer skin of your car was completely transparent so that, as you were driving to site, people could look inside and see you working the throttle, clutch & brake – could see the cam shaft rotate and the pistons oscillate. Temporary works design is exposed like this. There’s no rendered finish or architectural cladding to disguise the load path – everything is there to be examined. One of the upshots of this is that there’s also a greater emphasis on minimising superfluous materials and avoiding over-engineering of structural elements because costs are so much more difficult to justify for a temporary element. The design needs to be lean and efficient and it will be there for all to inspect and scrutinise.

We actively participate as a member the Temporary Works Forum and advocate for adequate consideration and management of temporary works design in the construction industry. In all of our design work, we consider not only what is to be built but, also, how it should be built and a deep knowledge of temporary works design and procedures is necessary for us to be most effective for our customers.