Sunday, November 11, 2012

Forty-seventh excerpt from 'Twelve Towers'

He turned as he heard the approach of Fred with the cart. On the cart with him were Siorys and three of the crew. They hefted the prince into the cart, tied him down and drove him to the summer residence of Artfael. Along the way they were joined by the mayor and the chief priest. The mayor and priest remained behind to ensure that the king did not release the son back into the town. The priest confirmed Gwilym’s suspicion of rabies. The king was grateful at the return of his son but devastated by the prognosis. “Rabies?! Is anything to be done?”
The priest related the symptoms, which had become all too common in this district. “He has been possessed by a fiend. It will throw his body around, freeze him up, cause him to spit at people and say terrible things, then kill him when done. It always ends in a terrible death. I’m sorry.”
“You can make his death painless, my lord,” spoke up the mayor. “And kill the fiend before it escapes to another man.”
The priest broke in to argue against this sin. Gwilym motioned to his crew and they set off back toward the town.

The next morning the crew walked over the site, comparing it to the charter, and discussed the scope and the requirements. Then they retired to the nearby tavern where they documented these last two. Next they developed a Work Breakdown Structure and the men volunteered for each activity until they were all accounted for. That took them to the end of the day so Gwilym dismissed the men and asked Fred and Bleddyn to stay behind.
“Bleddyn. Would you please stitch those activities to the hide so that we have a permanent record of the Work Breakdown Structure? Fred, help me write the activities of the Work Breakdown Structure on new pieces of leather so that tomorrow we can figure out how long they take and what they’re waiting on. Leave space for me to write down how long each activity takes.”
The three worked together for two hours, Fred often asking what a word meant while spelling it out to Bleddyn.
The next day, the crew entered the Sleepy Pilgrim’s hall to find that a full bull-hide had been clamped onto the two tables. On the wall was displayed another hide with the Work Breakdown Structure stitched to it. The charter, the scope and the requirements documents were nailed to the walls. The men walked around the room, marveling at this show of organization.
When they had settled down, Gwilym said, “We know WHY and WHERE this tower is to be built. We know WHAT is to be built and HOW it will be built. We know WHO will do what to build it. All we are lacking is WHEN it will be done. When do each of these activities need to be done? What is the most efficient sequence? How can we keep people from getting into each other’s way?”
He directed the men to the Work Breakdown Structure and asked them. “Which is the first activity?”
There was some discussion until the men agreed that staking out the foundation needed to be done first. Fred, who had the duplicate Work Breakdown Structure on the chair in front of him, fished out this activity and placed it on the new hide. Gwilym moved it to the top left of the hide and asked the man who had taken responsibility for it. “Is there anything stopping you from starting this activity tomorrow?”
The man shook his head and Gwilym asked him, “How many days will this activity take?”
“It will take a couple of hours, I expect.”
Gwilym wrote down ¼ in the space left for activity duration. “What’s the next activity?”
“Hey! What about this activity under the deliverable of road that says ‘Clear the site?’ Shouldn’t that be the first activity?” asked one of the junior members of the team.
The rest looked embarrassed and agreed with him.
Gwilym looked at the man responsible for the staking out activity. “Does the site need to be cleared before you stake it out?”
Gwilym moved the first activity to the right and took the clearing activity Fred had fished out for him and placed it to that activity’s left. “How long?” he asked of the responsible person.
“Three days,” was the response. Gwilym wrote this on the leather. “What’s the next activity?”
“Dig the foundation hole.”
“Buy the timber.”
“Measure for timber.”
“Bring up the stones.”
“All sound like early activities” said Gwilym. “Do any of them wait on any other activities?”
“Got to measure for timber and stone before we buy them and bring them up,” replied one.
“No sense bringing the stone up now. It will get in everyone’s way!”
“But if we wait too long we’ll be running short and delaying everything.”
Gwilym raised his hands. “Can we agree that measuring for timber and stone is the next activity?”
All nodded their heads and Gwilym moved this activity into place. “Buy timber?”
Again they agreed and Gwilym placed this next to the previous activity. “How about order stone?”
They nodded and Gwilym placed this activity below the ‘Buy timber’ activity.
This caused some discussion. “Why did you put the activity there?” asked one of the crew.
“This means it can be done at the same time as buying the timber but by a different person at a different place. Now, how long do these activities take?”
The men gave their durations and Gwilym wrote these numbers on the activities.
The team continued in this way, placing and rearranging activities on the bull hide and writing durations on the activities. The intricate structure of the work revealed itself to the team. Some activities were added during this session and other activities were determined to be unnecessary when looked at in the light of the overall project. When this happened, Fred made the appropriate adjustments to the Work Breakdown Structure.
At some points, the men took a while deciding on the duration of an activity. The first time Gwilym saw a man struggling, he asked “What’s going on inside your head right now?”
“Well,” replied the man. “I’m thinking about the last time I did this job and how long that took. It was eight days. But this job is about twice as big so perhaps it’s sixteen. But the weather was horrible last time and this time it looks like we’ll be doing it in June, not December. So I have to make adjustments for that. So I’ll say twelve days.”
Gwilym broke out into a broad smile and turned to the rest of the men. “See what he did there? That’s exactly what I want you to do. If you’ve done the activity before, and remember how long it took, use that as an example for how long this new activity will take. And don’t forget to make adjustments like Frank here did based on the realities. That is called…” he turned to Fred, “Analogous Estimating.”
When the time came to decide how long it took to build the main walls of the tower, the head carpenter talked out loud. “Each log will take an hour of carving to get the notches just right but we can do that with one group of men while the other places the previous log. So the time to do this activity is the time it takes to place each log properly in the tower. That will be pretty quick for the first few logs but will take longer as we have to start using winches to put them in place. So the ground level logs will take one hour apiece because we have to wait for the notches, then the higher logs will take about two hours a piece so that we’re careful not to drop them.”
“Good,” said Gwilym. “How many hours does that make it all together?”
The man calculated in his head. “Four logs per level, four high before we need to start using the winch, so it’s sixteen hours for the first eight feet. That’s two days with expected problems and setting up the winch for day three. Then it’s two hours per log after that, that’s one day per two foot layer. That’s sixteen more days. So a total of eighteen days to raise the logs to the top.”
Fred asked, “That’s different than ‘Analogous Estimating’ right? What do tha call it?”
“He’s using parameters and multiplying them by the number of units. Let’s call it “Parametric Estimating.”
One time the carpenters were arguing about the duration for building the stairs. As usual, Gwilym asked them to state the assumptions they were using to get to their estimates. One was assuming warm weather, the other was assuming cold and rainy weather. Since the stairs looked like they would be built in the early spring, it was unclear which assumption was most likely. Gwilym suggested a compromise. “Let’s assume first that the weather is perfect the entire time. How long would it take to build the stairs?” The two arguing men agreed on twelve days.
“Now we’ll assume it is cold and rainy the entire time, maybe even snow. Then how long will it take?” The men talked amongst themselves for a while and came up with a duration of forty days.
“Now we’ll take the most likely estimate. Assume a typical spring, with some nice days, some rainy, one day of snow. Now how long will it take?” The two men agreed on sixteen days.
“Good!” said Gwilym, writing these three numbers on the wall. “Now we do some mathematics. We take the optimistic estimate, add to it the pessimistic estimate and four times the most likely estimate and divide the result by six. So we have 12, plus 40 plus 4 times 16 equals 116. Divide that by 6 and we get a little over 19. So let’s estimate 20 days for this activity.”
The men appeared impressed. Fred asked him, “What do tha call that one, Gwilym?”
“Three-point estimating,” he replied. “They use that technique for calculating caravan journey times in the east.”
By dinnertime, the men were satisfied that the project had been fully planned. Fred and Gwilym started organizing the activities while the men helped themselves to dinner. “What do tha call this, Gwilym?” Fred asked.
“Sequence Activities,” he replied.
“Nay, not th’whole thing. I mean th’way tha decides one activity comes afore a nother?”
“Oh,” Gwilym thought for a while. “One activity depends on another so we should call it something like Dependency Determination. Does that sound formal enough for your song?”
While they ate, standing around with their trenchers in their hands, looking at the network diagram, Gwilym asked them each to find their own first activity. Then he said, “After dinner, the only people who can work are those who are working on the ‘clear the site’ activity for three days. The rest of you can go home.”
On hearing the expected sounds of disappointment emanating from the team, he said, “Unless you’d rather get in each other’s way and slow down the whole project.”
There was some grumbling until Siorys said, “How about if we all help with the clearing activity?” Then it’ll be done quicker and we can start our activities earlier and still be paid for the day.”
The other men perked up at this suggestion and looked hopefully at Gwilym. He seemed to consider this idea and then agreed to it. The men were all excited now and gulped down their meal to begin working.
As the men rushed out to clear the site and Gwilym stayed behind with Fred to stitch the activities into the bull hide, Fred looked long at Gwilym. “That was thy idea weren’t it? Having them all volunteer to clear th’site together? You made it seem like their idea but tha led them to it.”
Gwilym smiled, winked and touched the side of his nose. Then he looked at the project schedule. He drew arrows connecting all the activities together. Some activities moved in steady series, others were linked to more than one activity resulting in an intricate network of activities.

That evening, Gwilym, Fred and Bleddyn looked over the network diagram and started adding up the durations to try to predict the end date of the project. But as the network increased in complexity due to the multiple pathways he kept losing track. Bleddyn suggested he write the start and finish dates above each activity. So, he started at the first activity writing that as day one and finishing on day three, then went to the four activities that stemmed from this and had them all start on day four. Depending on their durations, they finished on different days.
One of these activities was predicted to take five days and, as he wrote a finish date of day eight, Bleddyn interrupted. “But what about Sunday, Da? The men won’t work on Sunday. Do we have to add a day for that?”
Gwilym thought for a moment, then shook his head. “Right now we’ll just figure out the number of days. Then, when we transfer the work to a calendar, we’ll take Sundays and other Holy Days into account. It’ll be too confusing trying to do it without the calendar.”
The difficulty came in when several activities converged on one and the start date depended on the finish of the last predecessor activity. But the men soon got used to it and were working together in unison adding up the days until they determined the total time required to complete the project.

Fred sighed and said, “That were confusin’. I’m used to addin’ five to four and comin’ up wi’ nine, not eight.”
Gwilym furrowed his brow and asked Fred to explain.
“We said that an activity starts on day four and takes five days. So tha think it will end on day nine. But it ends on day eight.”
Gwilym cleared his brow and smiled. “What’s the answer, Bleddyn?” he asked.
Bleddyn replied, “Sunup to sundown is on the same day even if a day’s work is done. So starting at sunup on day four and finishing at sundown on day eight is five day’s work.” He counted on his fingers: Day four, day five, day six, day seven, day eight. “Notice that the next activity starts on day nine. So if you look at the start of this activity and the start of the next activity, five days have gone by.”
Fred clapped the boy on his shoulder and flashed a broad smile. “Tha were always a clever boy, Bleddyn. Tha take after thy father.”

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