Activity-on-node logic for a medical office building, 109 ties and thirty-five lags, each justified and tagged physical, crew-flow or procurement, makes up MT381's Unit 4 diagram. Searches like "mt 381 unit 4 assignment example", "mt381 unit 4 sample" and "mt381 unit 4 example" land here.
What a finished MT381 Unit 4 network logic diagram looks like
Four tabloid sheets of a nine-page paper hold the diagram, drawn activity-on-node with one row per building zone, so procurement runs along the top, structure and envelope through the middle, and the three interior levels stack below. Boxes carry an activity code, name and duration; arrows carry the relationship type and any lag. A relationship register follows, all 109 ties in one table: predecessor, successor, type, lag in working days, category and a one-line reason. Seventy-eight are finish-to-start, twenty-one start-to-start and ten finish-to-finish. Thirty-five carry a lag, none is negative, and no activity except notice to proceed holds a date constraint. Every activity apart from the first and last has at least one predecessor and one successor, which the register confirms with a count at its foot.
How a MT381 Unit 4 example is structured
Logic is classified before it is drawn, because the three categories behave differently once the job starts. Eighty-five ties are physical: concrete cannot go onto deck that is not there, and a cover inspection must pass before board hides the rough-in. Eleven are procurement, submittal to review to fabrication to delivery ahead of each installation. Thirteen are crew-flow ties, the drywall, paint and ceiling crews moving from level 1 to 2 to 3, marked preferential so a later update can reorder them without pretending physics changed. Overlapping trades use paired ties instead of one arbitrary lag: framing leads the air barrier by five days at the start and two at the finish, so the barrier crew can neither overtake the framers nor trail far behind. Lags count working days on the standard calendar. The register ends with the two ties the author trusted least, and why each stayed.
Physical, procurement or crew choice
Every tie gets one of three tags. A physical tie survives any update; a crew-flow tie records a decision somebody could reverse; a procurement tie ends when material reaches the site.
Pairs instead of single lags
Steel to deck runs start-to-start plus ten and finish-to-finish plus three. The first tie alone would let decking wrap up before the final bay of steel stood plumbed and bolted.
Cure and bolt-up written as lags
Level 1 overhead rough-in waits three days after the level 2 pour so the slab can take hanger loads. Steel waits five days after the footing inspection for anchor bolts and grout.
No dates forced into the network
Only notice to proceed holds a date. Substantial completion lands wherever the logic carries it, so an upstream slip shows at once instead of vanishing behind a pinned milestone.
Two ties left open to question
Exterior framing starting two days into the level 2 pour, and ceilings moving between floors finish-to-start, are flagged as judgment calls a superintendent might reasonably set another way.
Where marks go in MT381 Unit 4
Trades overlap on real sites, so a diagram linking everything finish-to-start overstates the duration by weeks, and construction sections flag that pattern before any other. The opposite fault costs as much: start-to-start lags chosen to make dates fit, with no stated reason. Instructors typically sample a handful of ties and ask what physical fact each represents. An activity without a successor, often brick veneer or site paving on student networks, can push nothing later and so escapes the float calculation; prompts sometimes include one on purpose. Constraints pinning milestones to calendar dates override the logic and count as errors unless the contract imposes them. Crew-driven ties presented as physical ones mislead whoever updates the schedule next. Negative lags are best avoided, and explained wherever one survives.
Get a MT381 Unit 4 example written to your instructions
Networks start from the activity list and durations built in earlier units, so attach those with the rubric and note whether this section wants a hand-drawn diagram, a precedence layout or a software file. A first network comes back free in 24-48h, every tie carrying its type, any lag, a category and the reason it exists.
MT381 Unit 4 questions, answered
When should a construction network use start-to-start ties?
When a following trade can begin before the leading one finishes, as decking does behind steel erection or brick behind the air barrier. Pair the start-to-start with a finish-to-finish where the follower must also finish after the leader, and state the physical reason for each lag. Overlaps without reasons look like date-fitting to a grader.
What separates physical logic from preferential logic?
Physical logic reflects something that cannot be otherwise: concrete needs deck beneath it. Preferential logic reflects a choice, such as sending one drywall crew from floor to floor. Both belong in the network, but labeling them tells anyone updating the schedule which ties may be changed to recover time and which may not.
Are negative lags acceptable?
Many schedulers avoid them, because a lead lets a successor start before its predecessor finishes without saying what portion must be complete. A start-to-start tie with a positive lag usually expresses the same overlap more clearly. If your course or the specification permits leads, explain each one in the relationship register.