Safety by design: dialogues between designers and builders using virtual reality

Figures & data

Figure 1 Safety professionals inspecting a scaffolding scenario in the CAVE

Figure 2 Example of an unsafe design scenario embedded in the virtual construction site model

Table 1 Examples of translation of design recommendations into risk situations in the virtual construction site model

No.	ToolBox chapter	ToolBox design recommendation	Location in model	Method of presentation in the model
1	General conditions: special provisions	Minimize construction site visitation and public access through or adjacent to project site	Access road	The model comprises two structures: one is at occupation stage and the other is under construction. The access road to both buildings is within crane range, such that the crane oversails the public access route
2	Project component: technical specifications – steel	Limit the lift height of steel (or prefab concrete) erection	Roof	A steel pergola is modelled on the roof. Show two construction options: one with convenient support and screwing details, and the second with onsite welding without support details
3	Project component: work schedule /sequence – stairway	Schedule permanent handrails to be erected along with the structural steel as one assembly	Entrance lobby	Show a staircase with temporary handrail in entrance lobby. The permanent handrail is made of steel and is scheduled to be delivered only during the final stages of construction
4	Project component: work schedule/sequence – elevated work	In multistorey buildings, schedule the exterior wall structure and/or finish to go up with the structure or soon thereafter	Façade	Two situations are modelled: (1) Curtain walls whose installation begins only after 20 floors are built with temporary railings on each floor. (2) A curtain wall whose installation takes place in modules of up to 3 storeys whereby each floor is closed as the work progresses
5	Project component: structure plan/elevation – mechanical	Position control valves and panels away from passageways and work areas	Typical floor	A situation is modelled in which a water valve is located at head height
6	Project component: slab-on-grade, floor, roof	Design a permanent guardrail that surrounds every skylight	Roof	Two situations are modelled: (1) Skylight elevated by concrete parapet that is high enough to prevent workers from falling. (2) Skylight on roof level, without protection against falls. In both cases the glass in the skylight is missing
7	Project component: furnishing, finishes – ceilings	Minimize the complexity of construction of ceiling systems	Lobby	Installation of complex lighting fixtures in atrium lobby ceiling

Figure 3 Constructing the model: replicating a typical floor plan

Table 2 Classification of designers’ responses

Issue	Classification of designers’ responses
1. Does the designer identify the situation as a safety hazard for workers?	Yes
	Partially
	No
2. The designer’s opinion of the risk	Situation is not dangerous
	Situation is not dangerous provided appropriate means are taken/work is executed according to procedures
	Situation is dangerous
	Situation is very dangerous
3. Recommended way of handling the situation	No handling necessary
	The issue is a design consideration of another designer/consultant, not within my area of responsibility
	My design consideration supersedes, and so protective measures must be taken
	The design should be changed for safety reasons to minimize the risk.
	The design should be changed for other reasons (maintenance, aesthetics) as well as for safety reasons
	The issue involves the builder’s considerations; I would not dictate another solution

Table 3 Identified risks and aspects questioned and discussed by the safety professionals in the second pilot

	Areas with risks	Discussion duration (min:sec)	Summary notes on aspects questioned and discussed (including short direct quotations)
a	Voids on the middle floor	5:23	Unprotected voids, sense of scale, technique for managing voids dependent on span, if permanent void might put permanent barrier up as part of construction, shaft all the way through, useful, see how voids connect
b	Stairs	1:55	Why is that open? No reason, or if there is a reason, it needs edge protection. Why can’t you access throughout the building using the stairs which are part of the permanent design? Could change the design, bring those walls up with the structure, gives you protection at the same time
c	Scaffolding and cladding	3:24	Edge protection, how would you tie it into the building? Some sort of brackets to finish the cladding, void that things are dropping through. How are you going to get it up with the scaffold tied in? Add set-out lines for the lines of the cladding panels work out where the scaffold ties need to go. Ladder access up the scaffold, instead permanent stairs and scaffold lifts, accessed through the buildings. Work area access from outside
d	Crane	1:50	Now on the roof, issue with the crane becomes very obvious, lack of vision. Crane operators can’t see what they are doing. No reason couldn’t have a tower crane up through the middle, tower crane operator sitting above the project with a bird’s eye view, better access
e	Roof	2:15	How would that be finished? [Prefabricated, manual labour] huge issue there. Could crane it on. There would definitely be a case for building in edge protection. Do we know if this is an open courtyard?
f	Voids and roof edge protection	4:40	Would have rebar through that, don’t know what they are for. Fencing enclosure but these not within it. What are the openings for? Air-con. They are outside the safe area. Louvered barrier, part of installation. Need to understand it. What is obvious is, if that could be moved over it could provide a barrier without the need for temporary ‘man safety’ measures. For any new building you shouldn’t have to have any ‘man safe’ in place. You probably want to ask the designers why you have all these voids, half a dozen 9” circular holes. May be oversizing them as they are not sure of the detail

Table 4 Participants’ recommendations for handling design-related hazards

Recommended method	Responses (n = 290)(%)
1. No action necessary	11
2. The issue is not my area of responsibility; it should be considered by another designer	9
3. My design considerations supersede concern for safety, so protective measures must suffice	20
4. The design should be changed for safety reasons, to minimize the risk	24
5. The design should be changed for other reasons (maintenance, aesthetics) as well as for safety reasons	30
6. The issue is the contractor’s responsibility; I would not dictate any other solution	5

Table 5 Designers’ recommendations grouped by design stage

Recommended method	Design stage
	Schematic(%)	Detailed(%)	Construction(%)
1. No action necessary	13	10	14
2. The issue is not my area of responsibility; it should be considered by another designer	6	9	7
3. My design considerations supersede concern for safety, so protective measures must suffice	38	28	17
4. The design should be changed for safety reasons, to minimize the risk	25	30	21
5. The design should be changed for other reasons (maintenance, aesthetics) as well as for safety reasons	19	18	29
6. The issue is the contractor’s responsibility; I would not dictate any other solution	0	4	11

Table 6 Designers’ recommendations grouped by design subject

Recommended method of handling	Design subject
	Detailed construction details	Building systems details	Division of service areas	Structural details (rebar and steel connections)	Appearance & function of façade and entrance areas
	A(%)	B(%)	C(%)	D(%)	E(%)
1. No action necessary	17	7	8	10	13
2. The issue is not my area of responsibility; it should be considered by another designer	6	7	4	5	13
3. My design considerations supersede concern for safety, so protective measures must suffice	17	7	33	10	46
4. The design should be changed for safety reasons, to minimize the risk	22	50	21	40	13
5. The design should be changed for other reasons (maintenance, aesthetics) as well as for safety reasons	24	26	33	20	13
6. The issue is the contractor’s responsibility; I would not dictate any other solution	15	2	0	15	2

Table 7 Results of the post-experiment questionnaire

Question	Average	St. dev.
1. Were the hazards facing the construction workers clear to you?	4.1	1.4
2. To what extent did you feel that the scenarios represent real construction site situations?	4.0	0.8
3. How strongly are the hazards in the situations displayed related to the designer’s decisions?	2.9	0.6
4. How good was the visual display?	3.6	0.7
5. How reliably did the scenarios represent the real world?	4.0	0.5
6. How important is the architect’s attitude to site safety?	3.5	1.1
7. How important is the structural engineer’s attitude to site safety?	3.6	1.1
8. Was the construction method clear to you in every situation?	4.3	0.9

Figure 4 Examples from transcripts showing the impact of the designer–builder conversations

Table 8 Designer types

Approachattitude	a. Do not identify hazards	b. Identify hazards
c. Reject change	Type 1	Type 2
	10%	10%
d. Accept change	Type 3	Type 4
	50%	30%