These systems (known as Phased Evacuation) are very common in higher commercial buildings. In all buildings, the capacity of the building has a direct effect on the staircase widths to allow a simultaneous evacuation off all occupants. However, this means that very tall buildings would need multiple, or very wide staircases which take up valuable floor space. Indeed, there would be a point where the staircase provision takes up so much space, it would not be viable to construct the premises in the first place. A phased system relies on good fire compartmentation between floors and a complex fire alarm system which will detect a fire, identify it's location and evacuate people in a phased manner - with those at greatest risk leaving first. A voice alarm system is a key part in this strategy. The fire alarm system must also be able to deal with more than one actuation (perhaps on different floors) and be able to create evacuation plans for these eventualities. These systems are very effective in a well maintained building with a disciplined/trained workforce and good house keeping. In post 9/11 years, phased evacuations have caused some anxieties for staff in such taller buildings, but to be fair, an event which causes such a simultaneous and instant event is so rare not to even be considered. The FRA should provide you with info & reassurance that your building (or your part of it) is still fit for purpose. I would also ask the building managers for sight of their FRA.

I wonder if a skyscape system would be beneficial as escape apparatus from high raised buildings. This system was developed in Norway and used by BP offshore on the Miller platform.It was considered in 1991 a quick means of escape,got me thinking now.

I have worked in a couple of the taller tower blocks in central London, both about 19 floors, and found exactly what Messy described - voice alarm systems including sirens or bells. Most recent was Westminster City Hall(other was Centrepoint), and there were a number of problems when evacs took place: first, the sliding security barriers at reception on the ground floor did not always open(fail to safe) when the alarm kicked in, causing queues of people having to put their cards on the pads to get out - ridiculously slow and the foyer got dangerously packed very quickly; also, being central London - Victoria Street - some bright spark had the assembly point located on the other side of the road and this road was two lanes of very busy traffic in either direction. Due to the occupancy of the building - Westminster City Council and about twelve other organisations in the same building, this means up to a couple of thousand people having to cross two dual carriageways to get to safety! As well as this, it means that there is no possible way of ensuring head counts(is there ever) as most of the evacuees decided to ignore instructions to stay put, instead they went into one of the many coffee and sandwich places on the road. Last time I was there and the building evacuated, many of the office peeps just went straight into John Lewis next to the assembly point. Came out later bearing shopping bags. LFB were highly impressed. I was in the process of renegotiating the assembly point as I felt that its location seemed poorly thought out but in the middle of this, I moved to another role. I found out that the assembly point was right next to the assembly point for the aforementioned department store, which would have caused a bit of kettling if both buildings had evacuated at the same time. Unlikely, I know, but badly planned. There was a back exit, but this was a convoluted route and was routinely ignored during induction. This was shown when the barriers failed during an evac and most did not know of the existence of the rear exit. Each floor had fire wardens as part of the overall strategy, but there was limited willingness to be involved on some of the floors. The FM company who managed the building including fire and security tried their best but relied on the cooperation of tenants, which was patchy at best, and drills were difficult to arrange due to getting all the organisations within the building to agree to time and date. My advice would be to get a meeting arranged with whoever is the liaison for the managing agent/landlord for the building asap and find out the specifics of the evacuation strategy so that you can get your colleagues informed. I found that more information and involvement meant that more of my colleagues bought into it. I was fire and H&S manager for the organisation I worked for then and did not envy the FM company managing it, with non-compliant tenants and one particularly dim council bigwig who during one evacuation ordered his staff back upstairs as there was a meeting which was about to start which had been cancelled once already - while the sirens and voice alarm system was still telling people to evacuate. You can only rely on your own plans for whatever floors you are occupying, unless you are taking over the whole building, in which case you can properly control it. If you are only on one or a couple of floors, rely on your evac plans in line with the overall strategy. Other tenants on other floors will probably not give a monkeys about your staff, so look after your own staff and do not rely on other tenants. Sorry to be negative, but that is my experience of working within multi tenancy multi use skyscrapers.