For planning purposes, general site services such as roads, sewers, fencing and guard houses can be incorporated into Block A or, if extensive, can form a block of their own.

Obviously, the number of housing areas or high-rise blocks can vary with the size of the development. Roads and sewers and statutory services are part of their respective housing blocks unless they are constructed earlier as a separate contract, in which case they would form their own block or blocks.

Here again, the road and sewage system could form a block on its own incorporating the lorry park.

Here roads, sewers and underground services are divided into the various operational blocks.

Clearly, in the construction of a multi-storey building, whether for offices or flats, the method of construction has a great bearing on the programme. There is obviously quite a different sequence required for a block with a central core—especially if sliding formwork is used—than with a more conventional design using reinforced concrete or structural steel columns and beams. The degree of precasting will also have a great influence on the split of the network.

Roads, sewers and underground services could be part of Block J or be a separate block.

Depending on size, the process unit may have to be subdivided into more blocks, but it may be possible to combine K and L. Again, roads and sewers may be separate or part of each block.

Additional blocks can, of course, be added where complexity or geographical location dictates this.

It must be emphasized that these typical block breakdowns can, at best, be a rough guide, but they do indicate the splits that are possible. When establishing the boundaries of a block, the main points given at the beginning of this chapter must be considered.

The interrelationship and interdependence between blocks during the construction stage is, in most cases, remarkably small. The physical connections are usually only a number of pipes, conveyors, cables, underground services and roads. None of these offer any serious interface problems and should not, therefore, be permitted to unduly influence the choice of blocks. Construction restraints must, of course, be taken into account, but they too must not be allowed to affect the basic block breakdown.

This very important point is only too frequently misunderstood. On a refinery site, for example, a delay in the process unit has hardly any effect on the effluent treatment plant except, of course, right at the end of the job.

In a similar way, the interrelationship at the design stage is often overemphasized. Design networks are usually confined to work in the various engineering departments and need not include such activities as planning and financial approvals or acceptance of codes and standards. These should preferably be obtained in advance by project management. Once the main flow sheets, plot plans and piping and instrument diagrams have been drafted (i.e., they need not even have been completed), design work can proceed in each block with a considerable degree of independence. For example, the tank farm may be designed quite independently of the process unit or the NGL plant, etc. and the boiler house has little effect on the administration building or the jetties and loading station.

In the case of a single building being divided into blocks, the roof can be designed and detailed independently of the other floors or the basement, provided, of course, that the interface operations such as columns, walls, stairwell, lift shaft and service ducts have been located and more or less finalized. In short, therefore, the choice of blocks is made as early as possible, taking into account all or most of the factors mentioned before, with particular attention being given to design and construction requirements.

This split into blocks or work areas, of course, takes place in practice in any design office or site, whether the programme is geared to it or not. One is, in fact, only formalizing an already well-proven and established procedure. Depending on size, most work areas in the design office are serviced by squads or teams, even if they only consist of one person in each discipline who looks after that particular area. The fact that on a small project the person may look after more than one area does not change the principle; it merely means that the team is half an operator instead of one.

Natural breakdown into work areas is even more obvious on site. Most disciplines on a site are broken down into gangs, with a ganger or foreman in charge, and, depending again on size and complexity, one or more gangs are allocated to a particular area or block. On very large sites, a number of blocks are usually combined into a complete administrative centre with its own team of supervisors, inspectors, planners, subcontract administrators and site engineers, headed by an area manager.

No difficulty should, therefore, be experienced in obtaining the cooperation of an experienced site manager when the type, size and number of blocks are proposed. Indeed, this early discussion serves as an excellent opportunity to involve the site team in the whole planning process, the details of which are added later. By that time, the site team is at least aware of the principles and a potential communication gap, so frequently a problem among construction people, has been bridged.

Each subdivision has its own merits and justifies further examination.