June_1971 — Page 37

PNA applied to complete projects

KEY

E

ACTIVITY TITLE

earliest time of event

(()) event reference number

L latest time of event

activity duration

critical activities emphasised thus

BRICKWORK (ground floor)

FIRST FLOOR JOISTS

BRICKWORK (first floor)

BRICKWORK [topping out)

TILING

(4)

(4)

m

(2)

Fig. 5.

NOOF CARCASE/

(3)

CARPENTERS FIRST

FIXING

(2)

PARTITIONS

GAS

CARPENTERS SECOND

FIXING

(5)

PLASTERBOARD

PIPEWORK 28 AND PLASTER 11, PLUMBERS FITTING

(6)

(3)

FLASHINGS

GLAZING

RAINWATER PLUMBING

M

M

ELECTRICAL

CARCASE

GAS

(2)

[D]

INTERNAL

39 DECORATIONS 43

(4)

(2)

ELECTRICAL FITTINGS

M

EXTERNAL PAINTING

(2)

4

4!

BRICKWORK (ground Heat) (4)

FIRST FLOOR JOISTS m

BRICKWORK (first floor) (4)

TOP OUT

M

12:

TILING (2)

CARPENTERS FIRST

CARPENTERS SECOND

FIXING

PARTITIONS

(5)

PIPEWORK (3)

ט

(4)

FIXING

(6)

KEY

critical activities and heks aru m emphasised thus

ROOF CARCASS (3)

sarliest time of start

sarkest time of finish

ES

EF

ACTIVITY TITLE

(D)

LS

LF

latest time of start

latest time of finish

duration

KAINWATER PLUMBING (1)

FLASHINGS

(1)

145

GLAZING

a

EXTERNAL PAINTING

(2)

FLOOR FINISH

CLEAN AND

4 HANDOVER 45

ELECTRICAL CARCASS (2)

PLASTER

PLUMBERS FITTING

INTERNAL DECORATIONS

FLOOR FINISH

(2)

24

ELECTRICAL FITTINGS |

(3)

45

CLEAN AND HANDOVER

(1)

Fig. 6.

presented on this chart could not have been obtained without the use of the earlier network diagrams. This linked bar chart is, in fact, an arrow diagram drawn to a time scale. It may be found more useful to present this informa- tion to the executive team in small increments, for example, a fortnightly up-dating of the next four weeks' acti- vity starts.

The type of diagram shown in Fig. 7 may be set up on framework of horizontal wires on which slide beads, representing resources, with vertical wires connecting activities which have a precedence relationship. Various solutions of resource allocation to obtain an optimum use of float time may be tried; a simple method of com- munication to the executive team is a photograph of the most acceptable solution. Fig. 8 shows part of such a solution.

PNA need not be confined to site work, as in the previous example. By explicitly presenting the inter-relation- ships of the various activities that make up a project, PNA is especially useful in the design and planning stages.

Fig. 9 shows part of the arrow dia-

Far East BUILDER, June 1971 Page 37

POSSIBLE CALENDAR DATES WITH A 5-DAY WORKING WEEK

November

December

January

3 4 5 6 7 10|11| 12 | 13 | 14 | 17 | 18|19|20|21|24|25|28|27|28|| 1 | 2 | 3 | 4 | 5 8 9 10 11 12 15 16 17 18 19 22 23 24 29 30 31 1

3 19 22 23 24 29 30 31 1 256

NON-CRITICAL ACTIVITIES

The hatched portion represents the activity duration It may be moved to any place within the bar without extending the total project duration

The use of float on one operation may reduce the float on another

Example:-

If the glazing is delayed until its latest possible time the float of the external painting activity is reduced from 27 to 16 days

TOP OUT

GLAZING

す

RAINWATER PLUMBING

FLASHING

F

ELECTRIC CARCASS

GAS

EXTERNAL PAINTING

CRITICAL ACTIVITIES

PROJECT DAY NUMBERS

PLUMBERS

FITTINGS

ELECTRIC FITTINGS

CARPENTERS SECOND

FIXING

DECORATION

FLOOR FINISH

HAND OVER

1234567 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

Fig. 7.

gram for the administration and design procedures of a four-class primary school.

PNA has also been applied success- fully to large-scale planning, such as town planning (see reference 5).

Recent research into the feasibility of introducing a production bias to documents used in the preparation of tenders has indicated that a diagram showing a possible sequence of site operations may, with advantage, be

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