Internet Case - Cranston Construction Company
Cranston Construction Company
The Cranston Construction Company is a small Mississippi construction company that undertakes building projects of a medium-to large-scale nature based on local and statewide needs. Although the company is capable of operating outside of its native state, it usually does not bid on out-of-state business. It maintains an office with a small staff and usually has several construction projects going on at the same time. Cranston has just received the contract for construction of a new humanities building on the campus of Northern Mississippi State University.
Although the university and the State Building Commission are pleased to have completed negotiations for the new building, a significant task lies ahead for Mr. Daniel Cranston, the president of Cranston Construction Company. He must select a project manager and arrange for allocation of necessary resources for construction. He must then work with the project manager to develop a schedule for constructing the building in order to assist in the timely decision-making that involves financial needs and shifting of equipment from other job sites.
Mr. Cranston decides that the detailed planning, layout, and scheduling can be provided by his project manager. The project manager will further be delegated total authority for the construction operations, the execution phase of the project. Based on past experience, Mr. Cranston makes up a job breakdown with approximate costs (shown in Table 1). Since the bid was for over $1 million, these costs represent company targets and are confidential. Although Cranston does not have significant experience with critical path analysis, he also makes up the activity list and time allowances (shown in Table 2). These time allowances represent the span between the earliest date he thinks each activity can begin and the latest date by which each should end.
TABLE 1 Job Breakdown, Humanities Building
NumberActivity
1.Sales tax, bond, and insurance$22,000
2.General conditions25,000
3.Site work8,000
4.Reinforcing steel57,000
5.Concrete footings17,000
6.Concrete grade beams14,000
7.Structural concrete115,000
8.Structural and miscellaneous steel21,000
9.Masonry (includes stone)125,000
10.Roofing and sheet metal and insulation16,000
11.Doors and frames2,000
12.Architectural and miscellaneous metal and accessories5,000
13.Metal windows2,000
14.Lath and plaster24,000
15.Ceramic and marble5,000
16.Millwork34,000
17.Hardware9,000
18.Resilient floor10,000
19.Glazing and store front20,000
20.Acoustic ceiling10,000
21.Painting10,000
22.Elevator19,000
23.Carpet8,000
24.Finish grade and site work10,000
25.Clean up and move out4,000
26.Miscellaneous labor and materials20,000
Total Contract Price$612,000
TABLE 2 Project Activities and Duration
NumberActivityTime Allowed (days)
1.Sales tax, bond, and insurance35
2.Move in, tool house general conditions35
3.Clean, clear, excavate, and grade28
4.Reinforcing steel217
5.Concrete footings35
6.Concrete grade beams35
7.Structural concrete framing and slabs35
8.Structural and miscellaneous steel210
9.Masonry and stone231
10.Roofing and sheet metal80
11.Metal doors and frames203
12.Architectural and miscellaneous metal and accessories266
13.Metal windows231
14.Lath and plaster154
15.Ceramic tile and marble30
16.Millwork234
17.Finish hardware133
18.Resilient floor161
19.Glazing and store front203
20.Acoustic ceiling35
21.Painting161
22.Elevator119
23.Carpet35
24.Finish grade and site work28
25.Clean up and move out49
With these initial efforts, Mr. Cranston calls in Mr. Henry Nolton to discuss his appointment as project manager. After a lengthy discussion, Mr. Nolton accepts the appointment but makes the following statement to Mr. Cranston:
"Your cost targets are probably reasonable; however, your time estimates and activity list do not really provide believable information. According to your figures, the project will be finished in less than 370 days and, therefore, you will not incur any penalty costs. However, if most of your time estimates are close to being correct, then I believe that the project will take longer than 370 days. As an example, let me point out that your duration times look like total time allowances rather than activity times. Take the activity of "architectural and miscellaneous metals." I'd say that this would take about two weeks to complete and could be one of the last items accomplished, probably following completion of all the stairwells."
"Another major problem with your listing is that we'll be using reinforcing steel with all of the concrete work and, since it's a three-story building with a penthouse, we'll be doing concrete activities floor by floor. Thus, in order to schedule and control this job, I need to decide on an activity list which is based on the actual sequence of construction, floor by floor. floor concrete, the middle-floor columns and then the middle-floor concrete framing may be completed similar to the first-floor logic. After framing is complete, middle floor door frames, upper-floor concrete and lath and plaster activities can start. Lower floor masonry and middle-floor door frames must be complete before middle floor masonry can begin. Following lath and plaster, ceramic tile and marble can be placed. After the stairwells are complete, hardware, architectural, and miscellaneous metals can be installed."
"As with the first two floors, upper-floor columns are emplaced following the upper floor concrete work. Next, upper-floor concrete framing can be completed. At this juncture, upper-floor door frames, roofing, and elevator activities can begin. Once these three activities are completed, plus completion of middle-floor masonry, the upper floor masonry, penthouse work, and ceiling work can be started. Following ceiling work, painting can begin and must be finished before tiling and carpeting which follow millwork. The millwork and finish grading start after upper-floor masonry and penthouse activities."
Upon hearing this, Mr. Cranston decides to modify the activity list to make it more useful and more accurate. Working together, Mr. Cranston and Mr. Nolton put together Table 3 which gives all the relevant information.
Table 3. Revised List of Activities and Times
LabelActivity Immediate
Predecessors Duration (days)
ALayout, Excavate, and Grade - 28
BTax, Bond, & Insurance - 21
CMove In Tool House, General Conditions - 7
DGrade Beams A, B, C 11
EFoundation, Concrete footings A, B, C 11
FLower Floor Concrete D, E 10
GLower Floor Columns F 21
HLower Floor Frame G 35
IMiddle Floor Concrete H 12
JMiddle Floor Columns I 23
KMiddle Floor Concrete Frame J 37
LUpper Floor Concrete K 14
MUpper Floor Columns L 23
NUpper Floor Concrete Frames M 37
OUpper Floor Door Frames N 14
PRoof Slab, Beams, Sheet Metal N 21
QElevator N 21
RLathe & Plaster K 21
SUpper Floor Masonry, Interior Doors O, P, Q, II21
TPenthouse Steel, Concrete, and Masonry O, P, Q, II21
UCeilings O, P, Q, II42
VPaint U 42
WMillwork S, T 42
XFinish Grade, Sitework S, T 28
YTile & Carpet V, W 21
ZClean Up, Inspect, and Move Out X, Y, AA, CC, FF, GG2
AACeramic Tile & Marble R 14
BBStairwells H 35
CCHardware, Architectural and Miscellaneous Metals BB 14
DDLower Fl. Door Frames H 14
EELower Floor Masonry & Interior Doors DD 35
FFExterior Doors H 21
GGGlazing & Store Front H 35
HHMiddle Floor Dr. Frame K 14
IIMiddle Floor Masonry, Interior Doors EE, HH 35
1.Acting as Mr. Nolton's administrative assistant, draw a network to represent this project. Then develop a table showing the activities from Table 3, their durations, their earliest start, earliest finish, latest start, latest finish, and slack times. Identify the activities on the critical path.
2.Write a report to Mr. Nolton addressing the problems of project duration and specifying which activities may require the closest management attention. If it appears that the project will not be finished on time, identify the activities which might be considered for crashing if relevant time and cost information could be found.