The Maintenance Management Improvement (MMI) program performed a work sampling study for North Station Mechanical Maintenance. The team performed this study to determine the validity of in-house studies and to compare current performance against previous studies. The team also did the study to help accustom station personnel to being measured. A consultant performed the two previous studies of working (wrench) time in 1990 and 1991. In addition to comparisons to the previous studies, analysis of the current study proved the validity of the current study.

The results also suggest future studies can be done with greatly reduced efforts relying on 1-day-per-week observations. These studies should give ongoing feedback of performance and better acclimation of personnel to being measured. It is recommended such future studies be done.

Comparison to previous studies shows wrench time being the same despite changes in other time categories. Current wrench time is statistically unchanged at 35.08% or 3 1/2 hours per 10-hour day with a margin of error of 4%. The previous studies place wrench time at approximately 37% for past years. However, travel has improved from 21 to 15% and work assignment from 5 to 2%. But wrench time apparently does not rise because break times and unaccountable times get worse (as do material and instruction delays to a lesser extent). An analysis of the comments and the time of day for each observation indicate that scheduling and motivational concerns might be associated with these results. (For example, most of the unaccountable observations occur at day start, lunch, and day end.)

There are differences in wrench time among the crafts, with machinists being the...