Page 17 - Industrial Process Plant Construction Estimating and Man Hour Analysis

xxxii Introduction

where F ə ¼allowance multiplier for PF&D, number PF&D¼personal, fatigue,
and delay allowance, percentage standard productivity—time required by a
trained and motivated worker or workers to perform construction task while
working at normal tempo.

H s ¼ T n F ə
where H s ¼standard time for a construction task per unit of effort, hour. The
allowance for PF&D is 15%, which is an allowance multiplier of 1.176.
Definitions for nonrepetitive one-cycle time study are given in Table 2.

TABLE 2 Definitions for productivity analysis
Task/operation Designated and described work sublet to work measurement,
estimating, and reporting.
Normal time An element or operation time found by multiplying the average time
observed for one or multiple cycles by a rating factor.
Element A subpart of an operation or task separated for timing and analysis;
beginning and ending points are described, and the element is the
smallest part of an operation observed by time study. The length of the
element can vary from minutes, to hours, to days, etc.
Rating factor A means of comparing the performance of the worker under
observation by using experience or other benchmarks; additionally, a
numerical factor is noted for the elements or cycle; 100% is normal,
and rating factors less than or greater than normal indicate slower or
faster performance.
Observed time The time observed on the stopwatch/electronic clock or other media
and recorded on the time study sheet or media tape during the
measurement process.
Cycle The total time of elements from start to finish.
Continuous A method of time study where the total elapsed time from the start is
time recorded at the of each element.
Standard time Sums of rated elements that have been increased for allowances.
Allowance An adjustment for work, which includes delays, idle time, and
inefficiency, as well as efficient effort.
Delay One part of the allowance included in the standard time for
allowance interruptions or delays beyond which the worker’s ability to prevent.
Fatigue An allowance based on physiological reduction in ability to do work,
allowance sometimes included in the standard time.
Idle time An interval in which the worker, equipment, or both are not
performing useful work.
Person/man- A unit of measure representing one person working for one hour.
hour