Abstract:
Road changing i.s the activity of moving operating lines
on a cable yarding operation to permit access to logs in an
unyarded portion of a logging unit. The time required to
perform this activity varies widely and may consume a significant
portion of the total yarding time.
With rising costs in the logging industry, the efficiency
of cable logging systems is constantly under critical
review. Additional research in the area of road changing
has been suggested in several studies (Dykstra, 1974 and
Peters, 1973)
Road changing information was gathered on several yarding
operations in conjunction with detailed production
studies of cable logging systems. On six of the operations
the total time consumed by road changing was noted and
recorded as a delay in the yarding process. On four operations,
road changing was segmented into various activities,
and factors hypothesized to influence road changing time
were identified and measured.
On the four operations studied in detail, two crewmen
timed the road changing operation as the activities involved
occurred at widely separated locations on the logging unit.
The continuous time study method used on the overall production
study (Dykstra, 1975a) was also used during road
changing.
The analysis of road changing involves a descriptive
analysis of all the operations studied and a quantitative
analysis of road changing on the four operations studied
in detail. The descriptive analysis consists primarily of
a comparative investigation of road changing time between
the operations. The quantitative analysis consists of a
regression analysis of the four operations examined in
detail.
In the comparison of road changing times for the ten
operations observed, road changing time varied widely. Even
among similar systems a wide range was observed. This variability
was most likely due to the differences in the road
changing methods themselves, varying characteristics of the
logging units and lengthy delays encountered during road
changing. This could not be confirmed for six of the operations
as road changing was not recorded in detail. However,
among those operations observed in detail, this influence
could be seen.
Following a breakdown of road changing into machine
intensive activities, labor intensive activities and delays,
a large percentage of road changing time is occupied by
delays. Also, the greatest proportion of delay-free time
involved labor intensive activities. This was expected on
the operations where pre-layout of roads was not done. On
the operation where roads were pre-layed, other activities
requiring labor intensive action occurred. Some of the delays
encountered may have been due to characteristics of the particular
yarder being used.
A quantitative analysis was made of four operations.
Road changing time, excluding delays and the time required
to relocate the yarder was used as the dependent variable.
Delay-free road changing time was found to be a function of
the distance from the landing to the tailhold (SPAN) and
groundslope. For two of the operations, identical machines
and methods were used. A combined regression equation was
formed based on the independent variable SPAN. Also, based
on the scatter of observations for these systems, an equa.-
tion using SPAN2 as the independent variable was found to be
a better predictor of delay-free road changing time than SPAN.
