With excerpts from my Project Management Novel, I will illustrate the many processes of the PMBOK. Here is the twenty-sixth one: Control Schedule. Use this map to see how this process fits into the scheme of processes.
Fred and Gwilym were talking about how to make the most profit on this project. “In th’past,” said Fred. “We had to pay a premium for labor during harvest and plantin’ time. If we had more slack time in th’schedule, we could just let the men go free durin’ these times and save a lot of money.”
“True,” agreed Gwilym. “We need to Control Schedule just like we Control Costs. But how can we build in that much slack time?”
“We can measure it now, using this ‘Earned Value Analysis’ and look at Schedule Variance and compare it to th’Critical Path and see how we are really doin’. Then we can decide how much free time we have.”
“I agree that this Variance Analysis measures the slack time, but it doesn’t build any in,” said Gwilym.
The two men looked over the schedule and discussed different ways to speed up the plan during the cheap labor times.
“Remember how we did Resource Levelin’ to make sure we weren’t overusin’ our people?” asked Fred. “Couldn’t we add more people and raise th’level by one to shorten the timeframe?”
“Yes we could,” agreed Gwilym. “We can often make ten men do a ten day job quicker than five men. Sometimes it works better than others.”
“How does tha mean, Gwilym?”
“Well,” Gwilym thought. “Say we are digging a small hole. One man can dig at a certain speed. Adding another man gets in the way of the first man though they can spell each other and gets it done one and a half times faster. That’s not too efficient. But putting logs in place means that one man doesn’t have to keep moving from one end of a log to another and use levers and pulleys to put the log where it belongs. Three men moving logs is better than three times as fast as one man doing it. It’s probably ten times as fast.”
Fred was nodding all through this. “Aye! And layin’ foundations is th’same. Tha needs one man to bring th’rocks to th’other man laying them or he falls behind quickly. And we can use a lower cost laborer to bring th’rocks to th’higher priced mason. But can we lay rocks from more than one place at th’same time?”
“What do you mean, Fred?”
“Well. Say we have th’wooden walls of th’tower built. And we’re layin’ rocks around th’outside. Could we have one pair of men working on one corner, goin’ around th’tower and another pair working th’opposite corner and they meet each other’s walls about th’same time? Or would that cause problems if they are not at th’same level?”
Gwilym thought for a moment, then smiled broadly. “It could work! The masons first string around the tower already to ensure the level and build the rock up to that level. So, we could have as many as four masons working at the same time, one starting at each corner and building up a level to the next man’s corner. Then they lay the next string, that works better with four men, then go to the next layer.”
“Even better,” said Fred. “We could have one laborer for every two masons. They always work faster than th’masons because all they do is bring stones, the mason needs to select th’right stone and mortar it into place.”
“So let’s get this straight. With four masons and two laborers we could do the stone cladding at four times the pace of what we had scheduled? That’s amazing! We could clad this tower in 30 days rather than 120. And that is right on the critical path so every day we save is a day off the tower!” Gwilym was getting excited.
But Fred was shaking his head. “That might be too fast, Gwilym. We have to think about giving th’mortar time to set. Maybe we should only use two masons and one laborer. Can’t build it so fast it comes crashin’ down.”
Gwilym nodded in agreement, then said. “I like the term, though. ‘Crashing.’ That’s what we did to the schedule. Crashed a huge part of it by adding resources efficiently. We’ll halve the time of a major part of it by increasing our resources by one mason but all the men will be working for regular pay, not harvest pay.”
“There are other ways to speed up th’schedule,” said Fred. “We could do some of th’jobs at th’same time or almost th’same time rather than wait for one to finish.”
“We already do that. We’re building the roads while we build the tower. We gather supplies while we dig foundations.”
“Aye, but there are other jobs we could do in parallel. They’re a little riskier but we could do them. What about claddin’ th’lower stories of th’tower in rock while we are buildin’ th’higher stories. And even completin’ some of th’inner work while we build th’structure?”
Gwilym considered this. “You’re right about it adding risk. That’s the main reason we have always waited until the structure is complete before we work on the inside and outside. We’ve already run the cladding and inside work in parallel before when we’ve needed to catch up on the schedule because of bad weather. But what about running all three in parallel?”
“We will get in each other’s way when we’re tryin’ to lift th’logs up high,” said Fred.
“And if we drop a log in the process, we’ll destroy whatever work we’ve done below and probably kill some men.”
“When’s th’last time we dropped a log? I thought that finished with Tarrant,” said Fred.
“It’s still too risky to build inner work made of wood underneath a moving log. I won’t do it. But rock cladding should survive a falling log. Maybe a few rocks will need to be replaced. But we can’t risk men’s lives. How about this? We build the first couple of stories of log tower. Then we start cladding it in rock. But we stop work whenever we raise a new log in place. That only takes a few minutes each time. The men can stagger their breaks to fit that schedule. Then, once the tower structure is complete, we start work on the inside.”
Fred was looking at the schedule. “That will take a lot of time off th’schedule.” Do we call this crashing as well?”
Gwilym thought for a moment. “It’s different. Instead of adding resources, we’re moving deliverables and tasks to run in parallel. It’s like the tracks of a cart. Let’s call it ‘Fast Tracking’ instead. And let’s always think of the risks involved when we do it. Makes no sense to be gold-foolish while being copper-wise. I’d hate to save a couple of days and bring on a disaster that costs us weeks.”