ESTIMATE SHEETS.- After the reviews and revisions, prepare a list of equipment required. The list must include anticipated downtime. Sufficient reserve pieces must be added to cover any downtime.
To aid you in preparing the equipment estimate schedule, use such forms as those shown in figures 9-5 and 9-6. The important information on the forms
Figure 9-6.-Sample equipment estimate (sheet 2 of 2).
includes the sheet number, the name of the estimator, the name of the checker, date checked, battalion and detachment number, location of deployment, year of deployment, project number, and a brief description of the project.
TOA AND EQUIPMENT CHARACTERISTICS.- The table of allowance (TOA) of the Naval Mobile Construction Battalion (NMCB) contains specific information on the quantities and characteristics of construction equipment available to the NMCBs. Table 9-1 contains an abbreviated listing of such equipment.
There are two types of labor estimates: preliminary manpower estimates and detailed manpower estimates.
Table 9-1: NMCB Construction Equipment Characteristics
PRELIMINARY.- Use preliminary manpower estimates to establish budget costs and to project manpower requirements for succeeding projects and deployments. The estimates are prepared from limited information, such as general descriptions or preliminary plans and specifications that contain little or no detailed information. In some cases, you can make a comparison with similar facilities of the same basic design, size, and type of construction. A good preliminary estimate varies less than 15 percent from the detailed estimate.
DETAILED.- Use detailed manpower estimates to determine the manpower requirements for constructing a given project and the total direct labor requirements of a deployment. Take the individual activity quantities from the activity work sheet to prepare detailed estimates. Then, select the man-hours per unit figure from the appropriate table in NAVFAC P-405 and multiply it by the quantity to obtain the total man-hours required. When preparing the activity estimates in the format discussed earlier, you may use a copy of the activity estimates as a manpower estimate work sheet by adding four columns to it with the headings of Activity, Quantity, Man-Hours Per Unit, and Total Man-Days Required. Work sheets, whether on the activity work sheet or on another format, should be prepared in sufficient detail to provide the degree of progress control desired. For example, the work sheets should show the following information:
If the control is to be exercised only on concrete pipe installation without regard to detail, the manpower estimate should show the following information on the summary sheet:
Table 9-2.-Production Efficiency Guide Chart
The man-hours per unit on the work sheet is obtained by dividing the total man-days shown in the detail estimate by the total feet of concrete pipe times the unit to obtain the average man-hours. The man-hours per unit should be used for checking actual progress. You should check manpower estimates against the activity estimate to ensure that no activities have been omitted. NAVFAC P-405 provides labor estimates for the various projects undertaken by the Engineering Aids.
The Facilities Planning Guide, NAVFAC P-437, volumes 1 and 2, is an excellent source for preliminary estimates. Use it to find estimates for a wide range of facilities and assemblies commonly constructed. The P-437 not only gives the man-hours required, but it also gives a breakdown of the construction effort by ratings (BU, CE, UT, and so forth) as well as lapsed day estimates.
You must bear in mind that the lapse time from the P-437 is calculated using the contingency norm of a 10-hour man-day instead of the 8-hour man-day used in the P-405. For example, a specific task from the P-437 requires 100 man-hours (MH) of effort by the Utilitiesman. The optimum crew size is four UTs. This yields the following lapse time:
Using the P-405 and an 8-hour man-day, you will find that the same task yields the following:
In preparing manpower estimates, weigh the various factors affecting the amount of labor required to construct a project. These include weather conditions during the construction period, skill and experience of personnel who will perform the work, time allotted for completing the job, size of the crew to be used, accessibility of the site, and types of material and equipment to be used.
The production efficiency guide chart (table 9-2) lists eight elements that directly affect production. Each production element is matched with three areas for evaluation. Each element contains two or more foreseen conditions from which to select for the job in question. Evaluate each production element at some percentage between 25 and 100, according to your analysis of the foreseen conditions. The average of the eight evaluations is the overall production efficiency percentage. Now, convert the percentage
Figure 9-7.-Production efficiency graph.
to a delay factor, using the production efficiency graph (figure 9-7). It is strongly recommended that the field or project supervisors reevaluate the various production elements and make the necessary adjustments to man-day figures based on actual conditions at the jobsite.
The estimate of average Seabee production used in the NAVFAC P-405 tables falls at 67-percent production efficiency on the graph shown in figure 9-7. As you see, this represents a delay factor of 1.00. A delay factor of 0.66 represents peak production efficiency, equivalent to 100 percent.
In reading the graph, note that the production elements have been computed into percentages of production efficiency, which are indicated at the bottom of the graph. First, place a straightedge so that it extends up vertically from the desired percentage, and then place it horizontally from the point at which it intersected the diagonal line. You can now read the delay factor from the values given on the right-hand side of the chart. Let's look at an example of the process of adjusting man-hour estimates.
Assume that from the work estimate taken from the tables in P-405, you find that 6 man-hours are needed for a given unit of work. To adjust this figure to the conditions evaluated on your job, assume that the average of foreseen conditions rated by you is 87 percent. The corresponding delay factor read from the production efficiency graph is 0.80. You find the adjusted man-hour estimate by multiplying this delay factor by the man-hours from the estimating tables (6MH x 0.8 = 4.8 as the adjusted man-hour estimate).
The man-hour labor estimating tables are arranged and grouped together into the 16 major divisions of work. This is the same system used to prepare government construction specifications. The 16 major divisions of work are as follows:
The activities in the various labor estimating tables are divided into units of measurement commonly associated with each craft and material takeoff' quantities. There is only one amount of man-hour effort per unit of work. This number represents normal Seabee production under average conditions. As used herein, 1 man-day equals 8 man-hours of direct labor. Man-day figures do not include overhead items, such as dental or personnel visits, transportation to and from the jobsite, or inclement weather.
No two jobs are exactly alike, nor do they have exactly the same conditions. Therefore, you, as the estimator, must exercise some judgment about the project that is being planned. The production efficiency guide chart and graph (table 9-2 and figure 9-7) are provided to assist you in weighing the many factors that contribute to varying production conditions and the eventual completion of a project. You can then translate what is known about a particular project and produce a more accurate quantity from the average figures given on the labor estimating tables.