Posted on July 15, 2014 @ 08:31:00 AM by Paul Meagher
This is a follow up blog to my last blog, Redundancy Gets the Job Done. I felt it appropriate to
provide an update to the hay making project as I made some pretty strong claims as to the importance of redundant capacity
in getting time-constrained projects done on time.
On monday afternoon we had 900 square bales of hay in the loft of the barn.
We are about 35% done the making hay for the year. We'll make hay again when we have a good stretch of sunny dry weather.
All of our major pieces of machinery (two tractors, balers, rakes, and mowers) functioned without any
breakdowns, however, one piece of machinery we didn't have an immediate backup for was a hay conveyor,
more specifically, the motor on that conveyor because the heavy steel frame is very unlikely to fail.
A bearing in the electric motor driving the conveyor mechanism gave out so we had a critical piece of
equipment down while we scrambled to find a replacement motor. After some trial and error, we got a
1/3 hp motor to work (higher torque than 1 hp motors we tested). It was quite a bit slower than the 3 hp motor that failed, and it heated up alot
while it worked, but it got the job done for us.
So it appears we didn't do a deep enough analysis of the redundancies we should have in place to ensure completion of
the project in a timely manner (we lost a few hours in a very time constrained project). A hay conveyor breaks down so
seldom that we were not thinking about it as possible point of failure in the process. It is an interesting point to ponder
how we can become blinded as to what elements make up the critical path to completing a project. We can be blinded by the
reliability of an element to the extent that we don't consider it something that requires redundant capacity. A more
formalized process of mapping the critical path might have made us more aware of the importance of the hay conveyor in
the process and the consequences of it not working properly. Perhaps we would have had redundant capacity in
We have an old 4 hp motor from an air compressor that we are getting ready to adapt to the hay conveyor. If we can
get that working as the new motor, and fix the bearing on the old motor, then we should have enough redunancy
capacity to keep going through most machinery failures on the next round of hay making.
Googling the term "Redundancy Analysis" reveals that it is mostly used as a label for a statistical technique that
has nothing to do with project planning. Too bad. I think we should appropriate the term for a more useful
role to describe a type of analysis that should take place before projects begin where we examine the critical
path to completing the project and make decisions as to which elements of that path require redundant
capacity. Redundancy analysis can get a bit involved because redundant capacity can also slow down
certain types of projects such as software projects. We might think it is a good idea to have multiple
programmers working on a project, and in many cases it is, however, as the number of programmers goes
up, the amount of communication required to coordinate the coding effort can increase to the extent that
it slows the project down to add more programmers (see Mythical Man Month). Making hay is a different type of project than a software
project. I'll leave it as an open issue as to what features of a project make redundant capacity a good
thing and how much redundant capacity we should have in place for certain projects.
One final observation. Why do most North American families have 2 vehicles? In part is has to do with parents
both working and needing two vehicles, but even in situations where only one parent works outside the home, there
are often 2 vehicles. Transportation is such a critical element of modern living that we probably recognize, at
some level, the need for redundant capacity in our means of transport. Satisfying the need for redundancy, while
having only one piece of equipment, is a large area of opportunity for many entrepreneurs and helps the
environment by not requiring multiple copies of each piece of equipment (current solutions include equipment rental or sharing, farm machinery cooperatives, car sharing, etc...).