14.9 Marsh and Root Construction have won the contract to widen and resurface a section of road. The site manager has identifi ed the following tasks together with the tasks that must precede them and their anticipated durations:

Activity Description Precedence Duration (days)

A Relocate bus stop – 2 B Install temporary traffi c lights – 1 C Install safety barriers A, B 1 D Plane road C 2 E Lift kerbstones C 3 F Replace ironworks D 3 G Lay and roll tarmac F 1 H Replace kerbstones E 4 I Road painting G 2 J Remove safety barriers I 1 K Remove temporary traffi c lights J 1 L Restore bus stop H 2

(a) Construct a network to portray the project.

(b) Identify the critical path and hence ascertain the minimum duration for these roadworks.

(c) Marsh and Root Construction can earn a bonus of £1000 for every day less than 13 days the completion of the roadworks takes. They can crash the tasks listed below:
Activity Normal duration (days)
Crash duration (days) Crash cost (£)
D 2 1 600 E 3 2 200 F 3 2 300 H 4 2 500 Identify the activities that should be crashed and calculate the extra money they can make as a result.