Method and apparatus for finance-based scheduling of construction projects

• US 20030233303A1
• Filed: 06/17/2002
• Published: 12/18/2003
• Est. Priority Date: 06/17/2002
• Status: Active Grant

• Current Assignee: King Fahd University Of Petroleum And Minerals
• Original Assignee: King Fahd University Of Petroleum And Minerals
• Inventors: Elazouni, Ashraf
• Granted Patent: US 7,644,007 B2
• Time in Patent Office: Days
• US Class Current: 705/36.00R
• CPC Class Codes: G06Q 10/06316 Sequencing of tasks or work
• CPC Class Codes: G06Q 10/10 Office automation; Time management
• CPC Class Codes: G06Q 10/109 Time management, e.g. calendars, reminders, meetings or time accounting
• CPC Class Codes: G06Q 20/102 Bill distribution or payments
• CPC Class Codes: G06Q 40/00 Finance; Insurance; Tax strategies; Processing of corporate or income taxes
• CPC Class Codes: G06Q 40/03 Credit; Loans; Processing thereof
• CPC Class Codes: G06Q 40/06 Asset management; Financial planning or analysis

Abstract

a method and apparatus is disclosed for scheduling construction projects based on the available finance using integer programming. This method renders CPM/PERT schedules of construction projects executable using bank overdrafts of specified credit limits. Conveniently, the method is organized in three stages; input preparation, schedule extension, and model formulation. Input preparation stage supports preparing CPM/PERT schedule and financial data of the project. Schedule extension stage supports developing a scheme for schedule extension. The scheme is a framework of the original schedule that allows a definite extension increment in the critical path of the CPM. Model formulation stage supports building an integer programming model for the scheme and involves the components of formulating an objective function, setting constraints, and searching for a model solution. The model solution determines the activities'"'"' shifts that fulfill the constraints of the specified credit limit while minimizing the schedule extension. A search for a solution of the model is performed. If no solution is found, a repetition of the last two stages of the method is performed after allowing longer extension increment.

Claims

1. - A method for revising a CPMP/PERT schedule of a construction project that determines revised start times of activities and a revised duration for completing said project, such that said project can be adequately financed throughout said revised duration using a bank overdraft of a predetermined credit limit, using integer programming technique, whereby said schedule is rendered executable with respect to the available finance of said predetermined credit limit comprising the steps of:

devising a scheme that allows an extension of said schedule,

formulating a model for said scheme using said integer programming technique,

and providing a processor to solve said model and output an optimum solution.

15. - The method of claim 1 wherein the step of providing said processor includes:

setting said constraints of said model to intercept a plurality of points each one represents a solution of said model,

and applying a searching technique to search for said optimum solution that minimizes the value of said objective function.

16. - The method of claim 1 wherein the result of said optimum solution involves the value of said shift in each of said activities.

17. - The method of claim 1, further comprising if no said optimum solution is found, another said scheme is produced considering larger said extension increment until said optimum solution is found.

2. - The method of claim I wherein the step of devising said scheme involves adding an extension increment to the duration of said schedule to produce an extended duration for said schedule.

3. - The method of claim 2 wherein said extension increment is a plurality of days that are added to the total float of each of said activities to produce an adjusted total float.

4. - The method of claim 3 wherein said adjusted total float allows for a shift in each of said activities such that negative cash flows at the end of periods of said project undervalue said predetermined credit limit.

5. - The method of claim 4 wherein if said shift in each of said activities is within said respective adjusted total float, this causes said revised duration to remain below said extended duration.

6. - The method of claim I wherein the step of formulating said model for said scheme using said integer programming technique involves setting an objective function and a plurality of constraints.

7. - The method of claim 6 wherein said objective function of said model sets a goal of minimizing said revised duration of said project.

8. - The method of claim 6 wherein said plurality of constraints involves constraints of activity shifting, activity sequence, and said predetermined credit limit.

9. - The method of claim 8 wherein said constraints of activity shifting involve modeling of said shift in each of said activities to take up an integer value within said adjusted total float.

10. - The method of claim 8 wherein said constraints of activity sequence establish and maintain the dependency between said activities.

11. - The method of claim 8 wherein said constraints of said credit limit insure that said negative cash flows at the end of said periods undervalue said predetermined credit limit.

12. - The method of claim 11 wherein said predetermined credit limit could be constant of different for said periods of said project.

13. - The method of claim 11 wherein said negative cash flows at the end of said periods include accumulated net cash flows at start of said periods plus disbursements during said periods.

14. - The method of claim 12 wherein said disbursements involve direct costs of material, labor, equipment, and subcontractors;

and indirect costs of overheads, bonds, taxes, and financing costs.

18. - An apparatus for revising a CPM/PERT schedule of a construction project that determines revised start times of activities and a revised duration for completing said project, such that said project can be adequately financed throughout said revised duration using a bank overdraft of a predetermined credit limit, using integer programming technique, whereby said schedule is rendered executable with respect to the available finance of said predetermined credit limit, said computer comprising:

a memory to store the data of said schedule including start times, finish times, total floats, activity sequences, disbursement rates, and financial contract terms,

a work area to devise a scheme that allows an extension of said schedule by adding an extension increment of a plurality of days to said total floats of said activities to produce adjusted total floats that allow for shifts in said activities such that negative cash flows at the end of periods of said project undervalue said predetermined credit limit,

an encoded microprocessor to formulate a model for said scheme using said integer programming technique with an objective function that minimizes said revised duration and a plurality of constraints involves activity shifting that model said shifts to take up integer values, activity sequence that establish the dependency between said activities, and said predetermined credit limit that insure said negative cash flows at the end of said periods undervalue said predetermined credit limit,

a means for searching an optimum solution of said model that determines values of said shifts and minimizes the value of said objective function,

and a control mechanism that, if no said optimum solution is found, devises another said scheme considering larger value of said extension increment, formulates said model, searches for an optimum solution, and repeats until said optimum solution is found.

19. - A computer for revising a CPM/PERT schedule of a construction project that determines revised start times of activities and a revised duration for completing said project, such that said project can be adequately financed throughout said revised duration using a bank overdraft of a predetermined credit limit, whereby said schedule is rendered executable with respect to the available fund of said predetermined credit limit, said computer comprising:

a memory that stores the data of said schedule including start times, finish times, total floats, activity sequences, disbursement rates, and financial contract terms,

and, microprocessor being encoded with programming instructions, said instructions adapted to execute minimum extension of said schedule through shifting said activities to fulfill the constraint that said schedule is executable with said predetermined credit limit.