Construction planning

From Wikiversity
Jump to: navigation, search

Construction planning

Construction engineers use various methods of planning a project. Most common is Microsoft Project and Primavera. The Construction Planning Engineers visualize the sequence of Executing a project and present them in a graphical or table , Presentable format.

Gantt and PERT charts are methods used in the programming, planning and control of construction projects. These methods and applications can be used as an efficient and powerful project management tool system. Historically PERT was invented by the US Navy as part of the Polaris mobile submarine-launched ballistic missile project. It was then developed in the ‘50’s, primarily to simplify the planning and scheduling of large and complex projects and was seen as a ‘scientific management’ approach to project management which took on the aspects of Fordism and Taylorism.

The Program Evaluation and Review Technique commonly abbreviated PERT is a model and tool for project management. It is a basic and effective method to analyze the construction tasks involved in completing a construction project, especially the time needed to complete each task, and identifying the minimum time needed to complete the total project. In doing so, decisions can be made instead of it making decisions for the user. The illustration of a PERT chart is a display of interconnected events conventionally represented as numbered circles or squares. These are linked by arrows which either precede or succeed each activity. PERT charts are usually drawn on ruled paper with the horizontal axis indicating time period divisions in days, weeks, months, and so on. Although it is possible to draw a PERT chart for an entire project, the usual practice is to break the plans into smaller, more meaningful parts. This is very helpful if the chart has to be redrawn for any reason, such as skipped or incorrectly estimated tasks. On the Pert chart design these activity boxes can also split and run simultaneously in order to illustrate other areas of work within a project. These boxes contain start and finish dates, durations and earliest and latest start and finish dates. The advantage of this technique as a project management tool can be seen back in the times when computers were not so common. It meant that activities could be programmed on projects of differing magnitude and complexity involving a large number of tasks and dependencies, hence PERT is and was intended for very large-scale, one-time, complex, non-routine projects. It does, however incorporate uncertainty in the sense that it is possible to plan a construction project not knowing precisely the details and durations of all the activities involved such as bricklaying and the installation of windows. In this respect it is seen as an event-oriented technique rather than start- and completion-oriented. However PERT can dictate the critical path of a project which is the longest possible continuous pathway taken from the initial event to the terminal event. It also determines the total calendar time required for the project; and, therefore, any time delays along the critical path will delay the reaching of the terminal event by at least the same amount. Also Lead and Lag Time can be taken into account. These are the times by which a predecessor or successor event must be elapsed in order to allow a sufficient time for the following PERT event to start. Also, a project is to determine the tasks that the project requires and the order in which they must be completed. The order may be easy to record for some tasks (i.e. When building a house, the land must be graded before the foundation can be laid) while difficult for others (There are two areas that need to be graded, but there are only enough JCB’s to do one). Additionally, the time estimates usually reflect the normal, non-rushed time. Many times, the time required to execute the task can be reduced for an additional cost or a reduction in the quality. Critical Path Method (CPM) charts are similar to PERT charts and are sometimes known as PERT/CPM. In a CPM chart, the critical path is indicated. A critical path consists that set of dependent tasks (each dependent on the preceding one) which together take the longest time to complete. Although it is not normally done, a CPM chart can define multiple, equally critical paths. Tasks which fall on the critical path should be noted in some way, so that they may be given special attention. One way is to draw critical path tasks with a double line instead of a single line. Tasks which are on the critical path must receive attention by both the project manager and the personnel assigned to them. The critical path for any given method may shift as the project progresses and this can happen when tasks are completed either behind or ahead of schedule. This causes other tasks which may still be on schedule to fall on the new critical path. In this respect, the Gantt chart evolved with the Critical Path method.

A Gantt chart is a popular type of bar chart that illustrates a project programme. Gantt charts illustrate the start and finish dates of the activities and summary elements of a construction project. The initial format of the chart was developed by Mr. Henry Gantt (1861-1919) in 1910. The method was seen at the time as a revolutionary tool and was overlooked by the PERT method. By the 1980s, the PC eased the implementation and editing of elaborate Gantt charts or programmes. Gantt charts are now used in software applications such as MS Project. This software was primarily intended for project managers and construction planners. Nowadays, the Gantt chart has become a common technique for representing the phases and activities of a project work breakdown structure, so they can be understood by site management and subcontractors.

On a Gantt chart activity elements and summary elements comprise the work breakdown structure of the project such as excavation and concrete pouring. Some Gantt charts also show the dependency relationships between activities like the PERT chart. A Gantt chart used in construction can be a compilation of activities shown in a bar format. These bars can be linked together to show the sequence of activities. The longest sequence of activities is known as the critical path of the programme as described above. The advantage of the Gantt chart over a PERT chart means that a series of activities can be reviewed during a project and also can be used to show current status using percent-complete shadings in a vertical format. A Gantt chart programme can list all the tasks to be undertaken with start and finish dates and durations. Each activity can also have resources and costs assigned to them. The advantage of this means that the progress updating of the programme can be evaluated in terms of value undertaken and work complete on-site.

It can be seen that a Gantt chart has a distinct advantage over a PERT chart in respect that it is easier to be visually represented by showing activity bars instead of activity shapes which can be misleading to the reader. Also a Gantt chart can be represented in a graphical format indicating resources and the critical path. The most commonly used type in the Irish Construction Industry is the Gantt chart which is tried and tested using computer software applications such as MS Project.



BIBLIOGRAPHY

[http://studentweb.tulane.edu/~mtruill/dev-pert.html http://www.mindtools.com/critpath.html http://gates.comm.virginia.edu/rrn2n/teaching/gantt.htm http://www.netmba.com/operations/project/pert/ http://whatis.techtarget.com/definition/0,,sid9_gci331391_top1,00.html]

Books

Project Management Demystified – Geoff Reiss – E & FN Spon Practical Tools, Techniques and MS Project Scheduling – Dick Billows - PMI

THE CONSTRUCTION PLANNING MANAGEMENT METHODOLOGY

A. TENDER STAGE:

At tender stage the Contractor is required to produce the following:-

1. Tender Programme – Fully logic linked and rescheduled to identify the Critical Path, any float and earliest Completion Date. Allowances for Inclement Weather and Industrial Disputes are to be made and clearly identified.

2. Tender Specific Requirements – Information required to be submitted with the Tender includes:

2.1. Tender Programme as item 1 above 2.2. Labour Histograms 2.3. Method Statements 2.4. Cash Flow 2.5. Activity Schedule

3. Tender Planning Notes – All information used to arrive at individual activity duration’s and sequencing of the works (e.g. Breakdown of quantities, Chosen output, Resources, Calculations of duration, Specialist contractors used etc.). This should be produced as a spreadsheet relating to the BoQ.

4. Tender Planning Philosophy – A list of the main programme restraints, milestones and other important factors, including any alternatives considered, which may have an effect upon the programme. For successful tenders this will be expanded into a written narrative explaining the philosophy behind the Tender Programme.

The Contractor will be required to attend a Program Review Meeting with the Architect and Project Manager. This should be attended by the following Contractor’s personnel whom the Contractor proposes to allocate to the project – Project Planner, Project Manager, Site Manager, Contract Administrator, General Foreman and whosoever else the Contractor wishes to attend. The Project Manager and Project Planner will be required to give a presentation of the Tender Program philosophy explaining the logic behind the document.

This presentation will also require the Contractor to demonstrate fully logic linked activities with the Procurement Programme and the Architects/Consultants Design Programme.

The Program is required to address and identify specific programming issues including: the “weathering” of the Building, the early “hand-over” of dedicated areas, the interfaces with the Specialist Nominated Sub-contractors, the co-ordination of the Lift Services, Mechanical Services and Electrical Services Sub-contractors, management of Specialist Contractors/Suppliers (including suppliers and installers of Fittings, Furniture and Equipment) appointed by the Client and other relevant issues that impact on the completion of the project within the defined parameters for quality, time and cost.




B. CONTRACT AWARD – Contract Programme:

The Contractor is required to provide a Project Programmer who will be assigned to the project to fulfil the objectives for the duration of the Contract. The Project Programmer’s prime responsibility will be to ensure that all of the Project Programmer, Programming and Monitoring Objectives for the contract as set out in this document are met.

Prior to the award of the contract the Contractor will be required to prepare the following for acceptance by the Architect and Project Manager:

1. Contract Programme:

1.1. Developed from the Tender Programme on a Gantt Chart in format in sufficient detail to allow for accurate progress monitoring for contractual purposes. The activities on the programme must be fully logic linked and scheduled to identify the Critical Path to the project.

1.2. The programme is to be prepared with the following Key Drivers in perspective.

1.2.1. To record agreed intentions with the Project Manager, Design Consultants and Client.

1.2.2. To identify the project Completion Date, Handover Dates for Separable Parts of the Works, Power-on Dates, Commissioning, Snagging and the like.

1.2.3. To supply a timetable for co-ordinating the issue of design information, the placing of orders / delivery of materials and operations of plant and sub-contractors.

1.2.4. To provide a basis for assessment if interim valuations and ‘payment by results’.

1.2.5. To show the sequence of operations and output required from the Main Contractor and Sub-contractors.

1.2.6. To provide a yardstick for monitoring progress against forecast for individual activities.

1.2.7. To furnish the Client with milestone dates for decision-making and occupancy.

1.2.8. To identify the activities on the CRITICAL PATH for the construction works supported by ‘network logic arrows’.

1.2.9. To discourage changes in design by indicating the natural consequences, while at the same time facilitating amendments and minimising their harmful effects should contingencies arrive.




1.3. The detail to be depicted on the programme should be set out in accordance with the following guidelines:

1.3.1. A ‘broad’ Master Programme. 1.3.2. Intermediate/Section/Phase/Zone Programmes 1.3.3. Detailed Operation Programmes identifying the activity/activities to be undertaken. 1.3.4. Procurement Programme 1.3.5. Outstanding Information

1.4. Each and every activity on the programme is to be detailed to include the following detail:

1.4.1. Activity reference number 1.4.2. Activity name and outline description 1.4.3. Activity duration 1.4.4. Early Start date 1.4.5. Early Finish date 1.4.6. Late Start date 1.4.7. Late Finish date 1.4.8. Free Float for each activity 1.4.9. Total Float for the programme 1.4.10. Critical Activities 1.4.11. Preceding Activities (Precedence Diagram/Network Analysis) 1.4.12. Dependent Activities (as above) 1.4.13. Resources to be deployed on the specific activities

1.5. The programme chart must clearly identify Project Start Date and Earliest Completion Date for the project, including allowances for inclement weather and potential delays due to industrial relations disputes.


2. Contract Specific Requirements:

In addition to that outlined above, documentation to be submitted by the Contractor includes:

` 2.1. Labour Histograms 2.2. Method Statements 2.3. Cash Flow Forecast 2.4. Activity Schedule 2.5. Resource Schedule 2.6. Schedule of Submittals to be provided for the approval of the Client 2.7. Schedule of Samples to be provided for the approval of the Client




3. Contract Project Programmer Notes:

3.1. All information used to arrive at individual activity durations and sequencing of the works:

3.1.1. Breakdown of quantities 3.1.2. Chosen output 3.1.3. Resources 3.1.4. Calculation of durations 3.1.5. Specialist contractor used

3.2. This document should be produced as a spreadsheet relating to the BoQ.

3.3. All major items including Prime Cost and Provisional Sums must be accounted for.

4. Contract Project Programme Methodology:

A list of all programme restraints, milestones and all other important factors, including any alternative considered, which may have an effect upon the programme. This will be summarised into a detailed written narrative explaining the methodology behind the Contract Programme.

5. Procurement and Information Release Schedules:

As appropriate and linked to the Design Programme produced by the Architect and other design consultants.

5.1. These schedules are to be converted into a Gantt chart and are to outline the order of priorities and timetables for document release from the respective designers’ offices.

5.2. Symbols are to be added to the chart to indicate the latest dates by which information must be at hand in order to co-ordinate the supply of materials, labour and sub-contractors’ (on-site and off-site) works. Suitable symbols should identify the following as an example:

5.2.1. Latest date for drawings and details from the consultant

5.2.2. Latest date for bending schedules

5.2.3. Manufacturers drawings to be approved.

5.2.4. Nominations required.

5.2.5. Submittals to be approved.

5.2.7. Structural steel to be delivered

6. Sub-contractors:

Sub-contractors works must be scheduled so that their individual start (ES & LS) and finish (EF & LF) dates dovetail exactly into the overall timetable for the project.


C. CONTRACT PERIOD – Construction Programme:

The Contractor is required to ensure that every member of the Site Team, including specialist contractors and suppliers, must understand and fully commit to the Contract Programme.

Project Programming must be a continuous activity, hence, the preparatory groundwork of the Contract Programme must be extended by the regular preparation of Short Term Programs for both on-site and off-site activities.

The Construction Programme:

The Contractor is required to liaise with the Design Team to ensure that the Contract Programme is to be converted into the Construction Programme for the purpose of continuous programming, co-ordinating, monitoring and re-programming the construction works during the construction period.

1. Continuous Programming, Co-Ordinating, Monitoring and Re-Programming: must be systematically and analytically focused on the following objectives:

1.1. Site management must ‘look ahead’ to foresee future requirements and hence avoid delays

1.2. Review the actual performance achieved:

1.2.1. To ‘track’ performance against programmed activities 1.2.2. To identify and take corrective action for shortcomings, where required 1.2.3. To take advantage of any gains achieved

1.3. To incorporate any design modifications

1.4. To facilitate improved production techniques in the light of more detailed information and/or further investigation

1.5. To be developed by the Contractor in more detail than the Contract Programme to allow for construction management and detailed progress monitoring. Fully logic linked and re-scheduled to clearly identify the critical activities, activity float and projected milestone (e.g. weathering, power on etc.), sectional and contract completion dates. The Construction Programme is required to be a live document which must be continually reviewed, revised and re-scheduled taking into consideration all available information.

2. Short Term Project Programmes:

The Contractor’s Construction Programme will be required to comply with the following guidelines:

2.1. The Contractor is to prepare, at monthly intervals, an update of the Construction Programme specifically focused on the next four/five weeks ahead. The period may be varied to coincide with particular stages of the work – a Staged Possession/Handover Programme.

2.2 The programme is to be a translation of the actual progress achieved coupled with a forecast of work to be done to achieve completion of the project within the contracted time scale for the project (duly amended as approved by the Architect).

2.3. The layout of the updated Construction Programme is to be in the same format and to the same detail as that required for the Contract Programme with the following enhancements:

2.3.1. The time period is to be portrayed in weeks and days as appropriate for a Short Term Programme

2.3.2. Relevant operations are to be translated from previous programmes, together with any work outstanding from the previous periods (clearly identified separately) and any additions or items brought forward for any reason (clearly identified separately). Work packages are to be broken down into scope items/activities to a degree sufficient to reflect effective on-site management and off-site co-ordination of resources.

2.3.3. Particular emphasis should be placed on the maintenance of continuity of work for both labour and sub-contractors.

2.3.4. Every activity is to be systematically checked to ensure that:

2.3.4.1. Essential design and approvals information is or will be available to allow the activity to proceed as planned

2.3.4.2. Sub-contractor activities are proceeding in accordance with agreed time-scales.

2.3.4.3. Any potential bottlenecks or hindrances are to be thoroughly investigated and obviated.

2.3.4.4. Where necessary, proper correction action, redeployment and re-programming of the activity coupled with corrective action to dependent activities should be assessed in order to arrest any potential of ‘spillage’ to activities

2.4. The Contractor will be required to present the updated Construction Programme to reflect the following criteria:-






2.4.1. Each and every activity on the programme is to be detailed to include the following detail:

2.4.1.1 Activity reference number 2.4.1.2 Activity name and outline description 2.4.1.3 Activity duration 2.4.1.4 Early Start date 2.4.1.5 Early Finish date 2.4.1.6 Late Start date 2.4.1.7 Late Finish date 2.4.1.8 Free Float for each activity 2.4.1.9 Total Float for the programme 2.4.1.10 Critical Activities 2.4.1.11 Preceding Activities (Precedence Diagram/ Network Analysis) 2.4.1.12 Dependent Activities (as above) 2.4.1.13 Resources to be deployed on the specific

activities

2.4.2. The status of each activity on the programme with either the status indicated by way of shading to reflect the component of work complete, or lines beneath each activity to record “as built” information (i.e. days work, % complete, comments, A.I.s etc.).

2.4.3. A tabular report recording “slippage” of activities against programme.

2.4.4. A “Jagged Line” programme reflecting the status of each activity at the date of updating the document.

2.4.5. A “Rescheduled” Programme – showing the amended forecast Completion Date and the amended Critical Path for the project.


3. Progress Report: The Contractor will be responsible for making sure that all records, as built information and relevant comments are up to date and readily available. The Project Programmer will agree and record the % complete for each activity with the Project Manager at least once per month. The Project Programmer will then resource and update the Construction Programme accordingly.

4. Change Order Schedule: The Contractor will be responsible for ensuring that a Change Order Schedule is maintained on site to log all instructions, design changes and variations that are issued to him. Prior to the monthly Progress Report, the Contractor will assess the direct time delay associated with each instruction, design change and variation. The Contractor will then incorporate the changes into:-

4.1. The Contract Programme in order to assess the impact, if any, on the agreed Date of Practical Completion of the Project and an Extension of Time should be sought.

4.2. The Construction Programme in order to assess the revisions that have to be made to the programme in order to achieve the previously agreed Date of Practical Completion. 5. Monthly Programme Report: The Contractor will be required to produce a summary report in a tabular format. This report will address the following key issues:-

5.1. Progress to date.

5.2. Analysis of progress.

5.3. Critical Activities to be focused on for the next month.

5.4. Interface with the Design Programme.

5.5. Interface with the Procurement Programme.

5.6. Projected dates for hand over of dedicated areas and dates of Practical Completion for the Contract.

5.7. Substantiated requests seeking an entitlement for an Extension of Time to the Contract Programme based upon known changes/variations.

5.8. Recommendations for reprogramming the Construction Programme for the remaining works within the constraint of the original Completion Date.

6. Revised Construction Programme: Following the review of the Programme Report the Project Manager, in conjunction with the Architect, will decide whether or not the updated Construction Programme needs to be revised and/or accepted as presented.

The Construction Programme must remain a LIVE document throughout the contract.