13 Build Manholes
30
(6)
A
2 8 2.1.
Excavate for
Drains
(( 6 )
13
Lay Drains
60
(8)
EL. M/C
2. D. 2. L.
Hardcore to G.F Slat
10
Conc. Fons.
(5)
4 L
(6) /10\ 6. Conc.
23
0
3
5
}
16
Excavate to
Start exc.
Finish Exc
Set Out
Strip Site
Red Levels
to Fdns.
to Fdns
Start Bwk to D.P.C
Finish Brickwork to D.P C
[10
[(20
30
40
50
50
100
(2)
(2)
(3)
(4)
(7)
I.L.
I.L. M C
I.L. MIC
1.L. M/C
IL MC
4 B. 2.L.
(7)
4 B. 2...
Fwk, to Gr. Beams
26
Reint. to Gr. Beam<
28
120)
(130)
Fig. 8.
(3)
(2)
4 C. 2. L.
2. S. 2. L.
Table 3
28
3
34
Blinding to GF Slab
Start Cone to
G.F. Slab
110)-
140)
150
(1)
6. Conc
(4)
30
6 Conc.
Conc. to Gr Beams
(1)
& Conc
Example: Consider job
(40, 60) Excavate for drains.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Duration Job (40, 60)
Total Float Job (40, 60)
Event
Alternative Path
Earlier
No.
Durations
Time
Earliest Start
time Job (40, 60)
| | | |
150
34
140
34-4
30
Max time available
Latest Finish time Job (40, 60)
130
30-1
29
120
29-2
27
Fig. 8(a)
110
30-1
29
100
29-5 or 30—7 or
Example: Consider job (40, 60) (Excavate for drains) in relation to job (60, 100) (Lay drains)
27-3
23
90
23-7
16
80
23-6
17
70
16-6
10
60
23- -8
15
Duration (40, 60)
50
10-0
10
1 2 3 4 5 6
7
8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Max time available.
Total Float (40, 60)
Max time available (60, 100)
Earliest Start time
40
10
-3 or 15-6 7
Job (40, 60)
30
7.
-2
5
20
5. -2
10
3-3
3
0
Earliest Start time
job (60, 100)
Duration Job (60. 100)
Interfering Floor (40, 60)
These latest times are entered on the network diagram and enclosed in triangles.
The activities with equal earliest and latest event times are the critical operations. The chain of critical operations which runs through the diagram constitute the critical path. This is usually distinguished by a double or thickened line.
The basic techniques so far consi- dered have assumed that the resources are unlimited and available as requir- ed. This will very seldom be the case in practice. Any plan which does not take into account the restrictions im- posed by the availability of resources will be of little practical value.
Resources can be made up of men at varying levels of responsibility em- ployed either on or off the site, plant in the form of excavators, cranes, con- crete-mixers, lorries, etc. and materials such as aggregates, cement, reinforce- ment, pipes, etc.
Any of these resources may not be available when required and will there- fore affect the project duration.
Float
In order to be able to reduce the
effect of fluctuating demand on re-
Fig. 8(b)
Example: Consider job (80, 100) Build manholes in relation to job (100, 140) Finish brickwork to D.P.C.
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33
Earliest Start time Job (100,140)
Fig. 8(c)
Duration Job (80, 100)
Max time available
Earliest Start time Job (80, 100)
Duration Job (100,140)
Free Float Job (80 100)
Example: Consider job (50, 90) Finish excavation to founds in relation to job (90, 100) Start bwk to D.P.C.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
sources, it is important to know the Fig. 8(d)
Far East Architect & Builder July, 1967
Latest Finish
time Job (40, 50)
Duration Job (50, 90)
Earliest Start time Job (90, 100)
Max time available
Duration Job
Independent Floor Job (50, 90)
555