"Preplanning", perhaps a short version of the term previous planning, consists of preparing plans for how future work is to be performed.  The term "work improvement" is often assumed to relate to improving an on-going operation.  However, work improvement might be enhanced to an even greater extent if proper planning occurs prior to beginning work on future jobs.

Preplans are fairly common on a large-scale operation and on long-term projects. However, they are not used extensively for defining the details of tasks that are performed on day-to-day operations.  When properly employed, preplans can discover potential problem areas that could seriously hamper productive efforts.  If problems are identified before work is begun, corrective measures can be taken at a minimum cost. Preplanning may be considered to be more closely related to management by objective while traditional work improvement methods are more like crisis management or management by exception.

Preplans can be very profitable when properly used.  It is important to enlist the help and support of both supervisors and workers.  The specific goal of preplanning is to make the execution of task operations to go smoothly.  This can be done by focusing on such problem areas as interferences, shortages of materials, pitfalls, etc.  With preplanning, one is forced to anticipate problems and in so doing preventative steps can be taken to avoid them.

There may be a reluctance among some firms to spend money on preplanning.  The costs of adding employees for preplanning is a very direct expense.  On the other hand, the benefits realized from hiring such employees are indirect or even hidden.  A concerted effort to identify the benefits in relation to the costs will often provide convincing evidence of the merits of preplanning.  Procter and Gamble is one firm that has examined these benefits and its managers are now sold on preplanning as they see a great return on the investment.

Preplanning is an unusual discipline.  To be effective at preplanning one must question why tasks are performed in certain ways.  Because of this reasoning, it is often suggested that preplanning positions should be given to younger and inexperienced workers.  The inexperienced workers tend to be more open-minded to different ways of doing things. While serving in the preplanning positions the workers learn a great deal about the construction industry.  Thus, it serves as a training ground as well.

There are many types of preplans.  Different firms develop very unique preplans while others use more widely-accepted preplans.  Only a few types of preplans will be discussed.  The actual format of each can vary.
 

 JOB ASSIGNMENT SHEETS

Job assignment sheets are used to give guidance to workers in a crew as to the specific tasks to be performed.  These are usually prepared by the immediate supervisor.  The job assignment sheet should clearly spell out what is to be done.  Notes should be made on the job assignment sheet indicating how the work was actually performed.  Thus, historical records are immediately established for future reference (estimating) and costing (cost control).
 

BLOCK AND TASK DRAWINGS
(MINI PROJECT)

A block drawing is basically the synthesis (on a single sheet) of all the necessary information needed to complete a task.  This type of synthesis is needed when, for example, the architectural drawings do not show all items exactly as they are to be constructed or they do not include information that is shown elsewhere, such as in the electrical drawings or the mechanical drawings.  Thus, a block drawing could be prepared that will put all of the needed information on one page so it will not be necessary to examine every page in a set of plans.  When information is seemingly hidden in the plans, oversights can easily occur during construction.  By preparing block drawings, the work can be thought through more thoroughly in an environment that is not plagued by the distractions that often occur on a construction site.

It should be clear that every construction firm may not use or develop the same type of block drawings.  In the area of heavy construction, the most common type of block drawings are lift drawings for concrete placements.  These drawings synthesize all facets of the project affecting the placement of concrete.  Thus, the supervisor does not have to rely on a quick examination of the entire set of plans to check or verify the placement of the concrete forms.  The requirements to satisfy the structural, electrical, mechanical, and architectural drawings will all be displayed on a single sheet.  As in the case of lift drawings, a single sheet is often devoted to each "pour".  The block drawing may also address requirements that will reflect the needs of subcontractors and suppliers as indicated in their submittals of shop drawings.

A block drawing will help avoid the problem of a supervisor, such as a carpenter foreman, from having to return frequently to the plans as the work is being done.  The cross referencing in the plans is time-consuming and can result in items being missed and consequently omitted.  This is particularly costly if a concrete blockout for a duct chase or similar penetration is overlooked.  The block drawings should minimize this problem.
 

 MODELS

The term models refers specifically to scale models which are three dimensional representations of an entire proposed project or a particular part of one.  This is not to be confused with architectural models which are frequently used to "sell" projects to clients.  These are working models that are used to effectively plan work procedures and sequences.

Models can be used effectively to convey the spatial relationships of the parts of the project they represent.  They can be used in lieu of "blueprints".

Models have many successful applications and uses.  Some general rules should be followed, however, when using models for preplanning:

Rules in making models:

(1) Build the model to scale (there should be a consistent ratio between the model size and the project size).

(2) Show the scale on the model.  It should be clearly noted what the scale is, but other indicators of scale should also be used.  Use scale figures of people and equipment so that one can quickly establish a visual impression of the scale being used.

(3) Locate the north position

(4) Use color coding to enhance the clarity of the model.  Use different colors for different concrete lifts, different piping systems, etc.

(5) Identify major pieces of equipment, vessels, columns, valves, etc.

(6) Use durable materials so the model will not be damaged through normal use, manipulation and transportation.

(7) Use a level of detail that is useful.  Do not get too detailed.  Costs are directly related to the amount of detail.

(8) Use the proper scale, preferably the smallest possible scale that allows an adequate presentation of the information.

Rules in using models:

(1) Locate "free" areas where no construction activities will take place as these may be a good location for temporary storage, parking, or even the project office.

 (2) Check for clearances and access.  These will change as the project is being built so these changes must be considered.

(3) Look for safety hazards.

(4) Use the model to communicate with subcontractors as to how various tasks will be performed.

(5) Take pictures of the model and use the photographs in the field to communicate with supervisors and their crews.

(6) Use the models to train workers.

Models can be used to represent various types of projects.  They can be used to represent complex concrete placements (different color for each lift), rebar placements, special rigging problems, etc.
 

Advantages of using models:

(1) Communicate information quickly and at a low cost.

(2) All information can be comprehended at a glance.  Since it is easy to quickly grasp what is shown in three dimensions, it will be possible to devote more serious attention to the 4th dimension of time.

(3) They can be used to reduce interference problems.
 

Limitations of using models:

(1) Models can be bulky (they may have limited handling capability and often cannot be shipped).

(2) Models cannot be used well if they are enclosed in Plexiglas.  This is a temptation when the models look too "nice".

(3) Attitude problems may exist among the workers.  People who have mastered understanding drawings feel it is a threat to have an understudy who quickly grasps the information from a model.  The understudy would often require hours of study to extract the same information directly from the drawings.

 (4) There is a shortage of good materials for making models.  This is particularly true of construction equipment.  Good models of equipment with good functioning parts enhance the use of models.  Particular emphasis of scale models should focus on such things as:
    - turning radius
    - swing radius of cranes
    - center of gravity
    - boom reach
    - boom clearance

(5) One representative (Victor Costello) of an oil company (Phillips 66) stated that models were not used extensively.  He said that the problem lies in the shortage of good "model-builders".  Inexperienced model makers go from the design to the model rather than from the model to the design.

Several uses of models have already been mentioned.  Perhaps a little imagination is all that is needed to use models in any construction setting.

Models have been successfully used for concrete placement operations.  The various blocks making up the model represent concrete lifts or "pours".  The model can be used to locate cranes to check for accessibility.  Even the curing requirements between abutting pours can be analyzed for possible problems.  The blocks can be used to check the construction sequence of each of the pours.  The best sequence and the best method of placing the concrete can be determined.  Sequences will be controlled by forming, curing and stripping.  Each of these can be evaluated in the model.

Models using equipment can be used to check clearances, reach limitations, turning radius problems, center of gravity, training, etc.

Full-scale models may also be used.  These are known as "proto-type" models.  They can be helpful to check out difficult formwork installations, complex structural steel connections, etc.

Models are particularly helpful on piping installations such as occur on petro-chemical projects.  Conflicts or interferences between different piping systems can be quickly determined with models while only tedious and laborious study of the drawings might otherwise reveal the problem.  In fact, some firms have the drawings made from the model.  This is the best way to make models.  In that way the model is already being utilized in the design phase.

Models can be used for site planning and layout.
 

 ESTIMATING AND PREPLANNING

Preplanning can be useful when estimating or re-estimating the  costs of a project. Several means are available.

(1) Use the judgment of qualified experts.  Estimates of the time required to perform a task should be made by one who has experience.

(2) Use historical records from past projects to forecast future project costs. Historical data should be up-dated to reflect local conditions.  It is also helpful to recognize how a task, or the conditions under which a task was performed, may differ from the tasks represented in the historical records.  Appropriate modifications might then be made to the data retrieved from historical records.

(3) Computed or engineered standards can also be utilized.  A task could be broken into its basic or elemental motions and these could be summed to determine the actual time completion.  This is similar to the methods-time-measurement (MTM) approach which is an industrial engineering technique which breaks down repetitive tasks into very small units of time.  The MTM approach will be discussed later.  It must be remembered that since the method largely influences the time requirements, care must be used in selecting the correct method.

(4) Computer storage of data can also be a good source of information for estimating. Computers may also be programmed to assess particulars regarding a project. Regardless of the type of approach used, it should be understood that a standard approach is generally preferred.  This is true unless a more economical approach can be established.
 

PURCHASING AND PREPLANNING

Preplanning can be exercised when project materials are being purchased.  It must be remembered that ultimately the cost of the in-place materials is what is of primary importance.

Do not buy random length planking when all rafters are installed on 4 ft. centers.

Know the consequences of buying cheap lumber.  Much material may be lost in waste if the quality is poor.  Worse yet, the consequences of using materials that require their subsequent removal and replacement are extremely costly.

Consider the costs of handling materials when ordering materials in bulk or when materials are to be picked up elsewhere.

Consider the cost and the need of packaging.

Consider the impact of a complete buy-out at project start.  Storage may be a problem along with the possibility of theft, spoilage, handling, etc.  Yet, always remember to get a fixed price early before prices escalate.
 

PREPLANNING THE WORK SITE

The job site should be preplanned with regard to storage, parking, fabrication, and temporary facilities.  Find the center of activity and consider that location for support activities, job office, etc.  Give consideration to winds and their direction, drainage patterns, noise, dust, etc.