materi kuliah crash program

7/21/2019 Materi Kuliah Crash Program

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CRASH PROGRAM


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Construction Management

Construction management is here taken to be the

management of any aspects of the construction industry

It includes aspects of project management and general

management

Management applies to any kind of organisation

It applies to all organisational levels

The aim of managers is to create a surplus

Managing is concerned with productivity; this implies

effectiveness and efficiency


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Crashing of networks

Considerations

Distinction should be made between directcosts (i.e. costs of resources used) and

indirect costs(i.e. time-related costs such as

head office service costs etc.)

Willingness to do crash program ? ( case in one of developing countries)

Purposes

To reducethe normal project

duration to achieve contractual time

requirements.

To optimisethe project cost.


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Crash t ime Normal t ime

Act iv i tydurat ion

Ac

tiv

ityd

irec

tco

st

Time and cost relationshipActivity duration and resources demand are very closely

related. As the activity time changes so will the resource

requirement and hence the direct cost.

Crash point

Normal point


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Crash t ime Normal t ime

Act iv i tydurat ion

Ac

tiv

ityd

irec

tco

st

The relationship is usually simplified asshown below.

Time-cost relationship (cont.)

Crash cost

s lope


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COST SLOPE

Semakin cepat usaha akselerasi, semakin besar

kebutuhan akan sumberdaya tambahan dan

semakin besar pula peningkatan biayanya.

Costslope = c

t= crash cost - normal cost

normal duration - crash duration


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Methods of reducing activity duration

Possible methods of reducing (crashing) of activityduration:

Use of more shifts

Use of overtime

Use of additional equipment

Use of bigger gang size

Restructure organization based on split task( e.g. split task under construction management consultant)

Use of alternative construction method or sequence

Use of alternative materials Use of simple design (re-design) but it needs:

Pro-active monitor (in advance)

Agreement among parties involved

Within budget


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The crashing procedure

Perform the timing calculations for the projectnetwork using the normal durationsto identify thecritical path.

Examine activities on the critical path to select theone which can be shortened for least cost.

Shorten this activity as much as possible. This will bedetermined by the following:

Until the activity crash durationis reached.

Until the project required lengthis reached.

Until another path becomes critical. In this case,several activities need to be shortenedsimultaneously.


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A

B C D E

F

120

20 40 30 50

Example project

60Ac tivi ty N. du rat ion

(days)

C. durat ion

(days)

N.co st C.co st C.co st

/day

B 20 15 1800 2800

A 120 100 12000 14000

C 40 30 16000 22000

D 30 20 1400 2000E 50 40 3600 4800F 60 45 13500 18000

Tot .. dir ect co st 48300 63600

Ind irect co st = 200/day


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A

B C D E

F

120

20 40 30 50

60Ac tivi ty N. du rat ion

(days)

C. durat ion

(days)

N.co st C.co st C.co st

/day

B 20 15 1800 2800

A 120 110 12000 14000

C 40 30 16000 22000

D 30 20 1400 2000E 50 40 3600 4800F 60 45 13500 18000

Tot .. dir ect co st 48300 63600

Example project (cont.)

200

200

300

120

60

600


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Calculations

Act iv ity 140 (days ) 130 (days ) 120 (days) 115 (days ) 110 days)

A

B C D E

F

120

20 40 30 50

60

(200)

(200) (600) (60) (120)

(300)

A

B

C

DE

F

D.cost

Ind.cost

Tot.cost

48300

28000

76300

20*

+600

48900

26000

74900

40*

+1200

50100

24000

74100

115

15*

+1000

+1000

52100

23000

75100

+1000

+3000

+1500

35

55

110*

57600

22000

79600


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110 115 120 130 140

Projectdurat ion

Pro

jec

ttotalcos

t

10000

20000

30000

40000

50000

60000

70000

80000

Min imum cos t


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STUDI KASUS

Seorang kontraktor mendapat pekerjaan membangun

sebuah rumah dengan nilai kontrak Rp. 919.000.000,00

selama 40 minggu. Manajer proyek, yang diangkat untuk

mengelola proyek itu, menemukan sejumlah kesalahan

serius dalam proses estimasi durasi, yang menyangkut

kegiatan-kegiatan vital. Kesalahan ini menyebabkan

proyek dapat tertunda selama 8 minggu. Perjanjian

kontrak memasukkan sebuah klausul denda yang

besarnya adalah Rp. 2.000.000,00 per mingguketerlambatan.

Pertanyaan : Tindakan apa yang dapat ditempuh ?


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Rekapitulasi nilai kontrak sebagai berikut (dalam rupiah) :

Biaya langsung 714.000.000

Overhead cost (4 jt/minggu) 160.000.000

Laba 45.000.000

Biaya Total 919.000.000

Setelah mempelajari permasalahannya, manajer proyek

berhasil mengidentifikasi lima kegiatan yang durasinya dapatdireduksi :

Kegiatan Durasi Normal Durasi minimal Biaya per

minggu (Rp.)

B 5 3 4,5 juta

C 11 9 3,5 juta

E 8 6 4,0 juta

G 11 7 3,0 juta

J 10 8 11,0 juta

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