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DEPARTMENT OF MATERIALS
AND CONSTRUCTION
Construction Methods Improvement by
Time-Lapse Movie Analysis
J O H N W. F O N D A H L , Associate Professor of Civil Engineering, Stanford University
Constant and systematic methods improvement is an area for possible cost reduction that construction contractors cannot afford to overlook. The details of daily operations, including selection of methods, tools, and sizing of crews, are often delegated to the craft foreman. I t is proposed that construction management should assume more responsi- bility for the development and use of improved procedures. The use of time-lapse movies for analysis of operations is suggested as an addi- tional technique besides the uses of stop-watch time studies and cost accounting data. The advantages of this technique are discussed. An actual example involving erection of tubular metal falsework for an elevated freeway structure is used to illustrate a movie analysis study. Both equipment and procedures are described.
- THE AWARD of construction con- Every contractor treads a narrow tracts for public works in the United path. His prices must be low enough States is based solely on price com- to obtain a share of the work availa- petition. Detailed plans and specifica- ble but high enough to make a sufl^- tions are made available when the cient profit to justify remaining in project is advertised. Each eontrac- business. Success demands an active tor who bids is offering to build the and continual search for methods to same structure, to meet the same reduce costs. There are many areas standard of quality for materials and that offer possibilities for cost reduc- workmanship, and to complete the tion, and all are important. One of project within the same time limit, these is the improvement of field By law the award is made to the low- methods. Such improvements can be est responsible bidder. Hence the dis- of the more spectacular type that re- tinguishing factor between the ser- suit from a novel approach to a con- vices offered by one contractor and ventional problem, the discovery of a those offered by another is the total new technique, or a major equipment price quoted. modification to meet job conditions.
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Almost every issue of construction trade magazines contains examples of ingenious solutions that have given one contractor a competitive edge over others for a specific job. The possibility of these solutions makes construction works the exciting and challenging business that it is. However, a less spectacular type of methods improvement offers even greater possibilities for cost savings. It consists of systematic and sus- tained efforts to accomplish the rou- tine and detailed steps of each opera- tion in a more economical manner. In view of their importance, the treat- ment accorded these efforts by con- struction management generally falls short of what seems justified. Man- agement seems content to pass the responsibility for details on to the craft foreman or the worker himself. Once the general plan of operations has been determined and the major equipment has been selected, it is usually the foreman who chooses the tools, sizes the crew, schedules the daily routine, and selects the pro- cedures to be followed. This delega- tion of management control is ap- parently based on the assumptions that the foreman has gained such a degree of "know-how" from past ex- perience that he is the one best quali- fied to make these decisions and that he will be motivated to draw on the best practices he has learned. These assumptions are questionable. There are about as many ways to perform an operation as there are foremen that can be assigned to do it. The foreman is generally a temporary em- ployee drawn from the union hiring hall. His experience and ability may vary greatly. Often he does con- tribute or develop better methods than those used previously by his em- ployer, but unfortunately these usually leave with him at the end of the job.
A better situation would be for management to retain a greater share of responsibility for detailed per-
formance as well as for over-all plan- ning. The systematic and continual effort to improve methods should be conducted by permanent and dedi- cated personnel. The best practices that foremen and workers bring to the job should be retained and used by other crews on future jobs. More sophisticated procedures for analyz- ing operations and evaluating meth- ods should be developed. When im- provements have been developed, better ways of "selling" them to the foreman or worker who will execute them are required. To justify much special attention and analysis, an operation should be a repetitive one. Highway construc- tion offers greater opportunities for profitable study of methods than perhaps any other type of construc- tion. The highly organized and mechanized paving spreads give proof that this opportunity has been appre- ciated by the industry. On the other hand, the structures contractor is inclined to feel that most of his opera- tions are unique on each job. This is not as true as often imagined. A l - though an over-all operation may in- volve conditions that are not likely to be found in the same combination again, the individual steps required to accomplish the operation are likely to be very similar to the correspond- ing steps of many past and future jobs. So it is these steps, or sub- operations, that should be subjected to systematic analysis. U n f o r t u n a t e l y the contractor's principal formal tool for evaluating his work is not a very effective one for sub-operation analysis. A good cost accounting system is invaluable for control purposes. However, the unit costs obtained are generally for unique operations composed of many steps. To obtain costs for these sep- arate steps is beyond the capabilities of a cost accounting system. Such a system is based on the time distribu- tions made on foremen's report cards at the end of each day. A too detailed
166 M A T E R I A L S A N D C O N S T R U C T I O N
devote his efforts to improved docu- mentation. Figure 1 shows the field equipment used for a study. The 16-mm camera was tripped by a solenoid actuated by the small, tran- sistor timing circuit housed in a box mounted on the camera base plate. Power was supplied by a small 24-v storage battery hung from the tripod in a carrying case. The storage bat- tery may be recharged nightly or less frequently as required. The camera may be removed from the tripod and held by the operator to obtain close-
Figure 1. Field equipment for time-lapse movies, including electronic timer and battery power supply.
up pictures or to get into tight quarters. The timer will continue to operate from the power supply hung from the operator's shoulder. The office equipment for analysis work includes a conventional film viewer, or editor, equipped with a frame counter (Fig. 2). This enables the analyst to observe single frames as long as he wishes and to advance or reverse the film as slowly as he de- sires. Having selected cycle end points he may take frame counter readings at the beginning and end of each operation step and obtain time data. Other types of equipment are available for group presentations. Specially equipped stop-motion pro- jectors permit observation of single frames without film damage and allow films to be advanced or re- versed a frame at a time as well as at varying continuous speeds. These may range from simple hand-crank projectors to more elaborate, auto- matically controlled ones such as those sometimes used by football coaches to analyze plays.
A D V A N T A G E S O F M O V I E A N A L Y S I S
It was indicated that this approach can have several advantages over the more conventional stop-watch study for analyzing construction operation. Some of these advantages may be described as follows:
- Most construction operations in- volve crew activity and one or more pieces of equipment. The simulta- neous activities of each man and piece of equipment is important to record. Crew balance studies often indicate the most significant oppor- tunities for improvement. Data for such studies require about as many stop-watch observers as crew mem- bers ; however, a movie study permits a single observer to record all of the simultaneous activities accurately. By repeated observation of a cycle on film, the analyst may follow the ac-
FONDAHL: CONSTRUCTION METHODS IMPROVEMENT 167
Figure 2. Office analysis of films by means of standard editor with frame counter.
tivities of one man at a time and construct an accurate crew activity chart.
- Construction cycles are more likely to be irregular than regular making time studies difficult for even experienced i n d u s t r i a l engineers. Contractors generally must use per- sonnel that are not highly trained in time-study techniques. Because a film may be observed as many times as desired, away from the job, it is simple for even the amateur to draw useful data from irregular cycles. 3. Construction operations are in- fluenced by changing work conditions, weather, and surroundings to a con- siderable extent. Complete docu- mentation of the important condi- tions, or even a recognition of which conditions are important, is difficult. Where data will be used by others who have never seen the job, the conditions cannot be fully appreci- ated. A movie record gives a complete and easily understood documentation of work conditions.
- Proposed improvements, sup-
ported by arrays of stop-watch data, are difl!icult to "sell" to the foreman in the fleld. A graphic presentation, such as that which is possible by looking at a film strip, is easy to ap- preciate, encourages participation in further method improvement sugges- tions by the foreman, and allows him to evaluate more intelligently the changes from a practical standpoint in advance of their trial.
5. The movie studies are an eco- nomical means of data procurement. At 3 -sec intervals a 100-ft roll of film permits a single operator to re- cord completely a total of 314 hr of continuous operation. Data for a number of cycles of several steps of one operation can usually be obtained on a single film.
TUBULAR FALSEWORK ERECTION
As an illustration, a movie analysis study of a highway structures opera- tion will be described—the erection of tubular metal scaffolding as false- work for an elevated freeway struc-
FONDAHL: CONSTRUCTION METHODS IMPROVEMENT 169
time. The pictures showed the men and equipment involved. Knowing labor classifications and rates and knowing equipment use rates, costs were developed. To appreciate the relative importance of the costs of the various sub-operations, these costs were developed for a block of work common to all operations. In the ex- ample cited, a given number of square feet of supported roadway soffit was the common denominator. Table 2 shows sub-operations grouped in de- scending order of importance. Know- ing the relative importance of the sub- operations, the appropriate amount of attention may be directed towards each.
Having used the films to analyze the operations, improvements are sought. The common-sense questions of Why?, Where?, What?, How?, and When? asked about the details shown may suggest changes in even the simplest tasks. For example, the sub- operation "distribute sand for sills" is about as basic a job as can be en- countered. I t is accomplished by com- mon laborers and wheelbarrows mov- ing sand from a pile at the edge of the roadway site to sill locations marked by string lines. Foreman di- rections such as "a couple of you men take a wheelbarrow over and move some of that sand" gave a work cycle in which one man stood idle at the sand pile while the other wheeled and dumped the sand and then returned to help fill the wheelbarrow again. The formal approach of a crew bal- ance study is not required to suggest that costs might be reduced by send- ing one man to do the same job instead of two. Not only are costs cut in half because the crew is cut in half but costs are further reduced, as shown by other filmed cycles, because one man working alone fills the wheel- barrow faster than two men chatting with each other as they work to- gether. But this is only one possible improvement. Another detail noticed was that the wheelbarrows being used
were of the ly^-cu f t garden variety. A laborer could just as easily wheel 5 or 6 cu f t per trip i f given a proper- ly sized piece of equipment. When this film was shown at a meeting of job superintendents and foremen, one of the men observed that an entirely different approach had been used on his last job. A special chute had been provided for the tailgate of the truck, and the sand had been dumped direct- ly along the sill lines upon delivery to the site. Another point that came up for discussion at this meeting was "Why do i t at all?" Under some con- ditions a careful grading job might permit the omission of sand bedding. Another alternative is the use of small, individual pads under each tower leg instead of continuous sills. This affects both the distribution of sand bedding and the more costly crane operation of handling the heavy timbers used as sills. There are good reasons for adopting one alternative over another, but these can be profit- ably documented for future reference to insure that an alternative is not blindly used when the reasons for it are absent. This simple example would hardly justify much formal attention. But, as is the case with practically all operations filmed, it is effective in making job management conscious of several points. First, there are num- erous possibilities for cost reduction through measures that are properly management functions, including giv- ing specific directions as to the manner in which a task is to be per- formed, sizing the crew properly, and selecting the best tools to furnish the workmen. Second, there is more than one way to accomplish even a simple task. I t is only by the continual at- tempt to seek out the best, retain it, and see that it is used until a better procedure is developed, that real cost reduction can be achieved. Third, there are possibilities on many small, routine tasks of cutting costs not by 5 or 10 percent but in half, or to a
170 MATERIALS AND CONSTRUCTION
fourth or even to a tenth of their present level. Or stated conversely, where management does not assume its proper responsibilities, costs of many sub-operations can increase in the order of magnitude of 100 to 1,000 percent without the reasons being readily apparent even to those in charge of the work. The same contractor that erected the falsework in the foregoing ex- ample was concurrently performing a similar freeway job in another city. Many of the corresponding operations were handled quite differently. Even on the same job, the same operation is performed by different methods from time to time. This is the natural result of the fact that management has turned over the selection of detailed methods to temporary em- ployees with different backgrounds of experience. The sub-operations them- selves are often quite similar in scope from job to job. In the case of erect- ing tubular metal falsework, the procedure for aligning and plumbing a tower, for installing caps on top of it, or for doing practically any of the 33 sub-operations of Table 1 is little affected by whether the job is in San Diego or Philadelphia. More- over, these are operations that will be repeated by the same contractor and by different contractors many millions of times. More attention to detailed performance seems justified. Incidentally, comments on the ex- ample used for illustration are not a reflection on the abilities of the contractor doing this work; rather, the reverse is true. This company is one of the biggest and best in the United States. Its work receives more detailed planning and is in the hands of more competent supervision than the vast majority of similar jobs. In general, its procedures could serve as models to guide others. So i f there are opportunities for method im- provements in its work, as it would be the first to agree, then there are
even greater opportunities for most other organizations. More important examples than falsework operations can receive similar analysis. For example, building form panels in the yard, erecting and stripping box girder forms, erecting and stripping column forms, handling and driving piles, and placing concrete are all operations that involve greater costs and also have repetitive sub- operations.
SUGGESTED PROGRAM
A systematic procedure for man- agement control of job-level opera- tions might include the following steps:
- Analyze operations and attempt to develop the best methods for their performance. Draw on job personnel assistance at all levels in evaluating procedures. Just as safety meetings can create safety consciousness, meth- od study sessions can create con- sciousness of method improvement opportunities. Films can often be used for both of these purposes simultane- ously, inasmuch as a revised method cannot be a better one unless it is also a safe one.
- Maintain a record of the best methods to be used with appropriate documentation of the reasons why it is considered best. (Table 3 gives a sample for the sub-operation discussed.)
- Go over these methods with supervisory personnel, and workers also when practical, at the beginning of a job to obtain their cooperation in the use of methods.
- Prepare pre-plans of work in order to assure that the proper tools and materials are available, the per- sonnel is instructed as to how to ac- complish the work, the crews are sized correctly, and units of work are performed at the proper times.
- Encourage job personnel to chal- lenge the "best" ways that have been
172 MATERIALS^ AND^ CONSTRUCTION
ACKNOWLEDGMENT
This work was made possible by a research contract awarded to the Civil Engineering Department at Stanford University by the Bureau of Yards and Docks, U. S. Navy. The purpose was to investigate and develop possible cost reduction tech- niques for construction operations.
The use of time-lapse movies for methods analysis is only one of several areas of study undertaken under this contract. For assistance on the tubular scaffolding example, the author is indebted to Henning Jakobsen, a former graduate student in the construction engineering pro- gram at Stanford.
