Should I use a triangle activity in TILOS?
In TILOS, a triangle is a display type you apply to a normal line activity. It doesn’t change how the activity is scheduled. It shades a triangular area attached to the activity line, showing the part of the time-distance chart the work occupies, so nobody plans other activities there.
This guide walks you through it in five steps, then shows a worked example you can copy.
Step 1: Understand the line activity
On a time-distance chart, a line activity runs at an angle: it moves along the chainage as time passes. Think of a crew paving from km 0 to km 5 over four weeks.
A plain line only says “the crew is here at this moment.” It doesn’t show that the ground behind or ahead of the crew is also tied up.
Step 2: See what the triangle adds
Picture the sloped line as the long side of a right-angled triangle. TILOS shades that triangle on one side of the line.
The shaded area means “this stretch of road, during this period, belongs to this activity.”
Why use a triangle instead of a normal line?
A normal line tells you one thing: where the crew is on each day. It says nothing about the ground before the crew gets there or after it leaves. On real sites, that is often the part that matters most.
Take a simple case. A crew pours concrete at 100 m a day, and each section then needs 3 days to cure. Someone plans road markings to follow 2 days behind the pour, at the same speed.
With lines only, the plan looks fine. The two lines run side by side and never touch, so a reviewer sees nothing wrong. But the markings are always 2 days behind the pour while the concrete needs 3, so the crew would be painting on wet concrete along the whole road.
With Triangle upper and a 3-day time lag, the curing appears as a shaded band behind the pour. The road markings line now runs straight through it, and the problem is obvious at a glance.
So you use a triangle when:
- The work leaves something behind that stops others using the area for a while: curing, drying, settlement, testing or a protected zone.
- The work needs space prepared ahead, such as traffic management, a cleared site or survey set-out.
- Other crews follow on the same stretch, and you need to see how close they can safely get.
- You want one activity to tell the whole story, instead of adding a separate “curing” line after every pour.
If the work leaves nothing behind and needs nothing ahead, a normal line is enough.
One thing to remember: the triangle shows the constraint but doesn’t enforce it. If the gap must drive the dates, also link the two activities with the right lag. The triangle then makes that logic visible to everyone reading the chart.
Step 3: Choose triangle lower or upper
There are two versions, and they shade opposite sides of the line. Ask one question: is the area blocked before the crew arrives, or after it has left?
| Type | What it blocks | Use it for |
|---|---|---|
| Triangle lower | The zone before the crew arrives at each point | Set-up, installing a traffic-management zone, ground kept clear ahead of the work |
| Triangle upper | The zone after the crew has passed each point | Concrete curing, settlement time, earthworks where cut is reused as fill nearby |
An easy way to remember it: lower = before, upper = after.
Step 4: Adjust the size with lags
A plain triangle is rarely the right size, so expect to adjust it in the activity’s Display tab. The Triangle lower and Triangle upper options include:
- Distance lag: extends the blocked area behind the activity line, in distance units.
- Distance lead: extends it ahead of the line.
- Time lag: extends it in time, at the start for a lower triangle or at the end for an upper one.
- Lag date: sets the date the fill begins from.
Step 5: Set it up in TILOS
- Draw a normal line activity, for example “Earthworks km 2–6.”
- Select it and open the Display tab in the Object Properties pane.
- Change the Activity Type to Triangle lower or Triangle upper.
- Add distance or time lags until the shaded area matches the real occupation on site.
- Right-click the activity and choose Save as template, so you can reuse the same look for similar activities.
Worked example: concrete curing
A crew pours a concrete slab from 0 m to 500 m at 100 m per day, so the pour takes 5 days. Each section then needs 3 days of curing, and nobody can work on it in that time.
- Draw the line. Insert a line activity “Concrete pour” from 0 m to 500 m over 5 days.
- Pick the side. Curing happens after the pour, so choose Triangle upper.
- Change the display type. In the Display tab, set the Activity Type to Triangle upper. The area after the crew is now shaded.
- Add the curing time. Set Time lag = 3 days. Each section now shows as blocked for 3 days after its pour.
- Read the result. The section at 0 m is blocked from day 0 to day 3. The section at 500 m is blocked from day 5 to day 8.
- Check the next activity. Draw “Road markings” so its line stays outside the shaded area. If it cuts through, you’re painting on wet concrete, so move it later.
If the crew instead needed traffic cones set out 2 days before reaching each section, you’d use Triangle lower with a 2-day time lag at the start.
Why a triangle? Gantt chart vs TILOS
A Gantt chart shows the pour and the curing as two bars, one after the other. It says the whole 500 m slab is poured on days 0–5 and cures on days 5–8, so road markings can’t start until day 8.
But the slab isn’t poured in one go. The crew pours 100 m a day, so each section starts curing on a different day. A section is free once its last metre has cured.
| Section | Poured | Curing (blocked) | Free from |
|---|---|---|---|
| 0–100 m | Day 0–1 | Day 1–4 | Day 4 |
| 100–200 m | Day 1–2 | Day 2–5 | Day 5 |
| 200–300 m | Day 2–3 | Day 3–6 | Day 6 |
| 300–400 m | Day 3–4 | Day 4–7 | Day 7 |
| 400–500 m | Day 4–5 | Day 5–8 | Day 8 |
The dashed rectangle is what the Gantt chart blocks; the coloured staircase is what’s really occupied.
Step by step: from blocks to a triangle
- Plot each section on the time-distance chart, with distance across and time going down. Each section gets a small pouring block with a taller curing block under it.
- Each section starts one day later than the one before, so the blocks step down to the right.
- Look at all the blocks together. They form a staircase that follows the slope of the pour line.
- Make the sections smaller (50 m, 10 m, 1 m) and the steps shrink too. In the end the staircase becomes a smooth sloped band along the line.
- That smooth band is what TILOS draws with Triangle upper and a 3-day time lag. The triangle is simply the smooth version of the staircase.
- Compare it with the dashed Gantt rectangle. Its bottom-left corner is free ground the Gantt chart still treats as blocked, so road markings can start at 0 m on day 4 instead of day 8.
An everyday analogy
Think of mopping a long corridor. You start at one end and work your way along. The floor behind you is wet, but the first metres dry while you’re still mopping the far end.
A Gantt chart puts one “wet floor” sign on the whole corridor until the very last metre is dry. TILOS shows the wet strip moving along behind you, so people can walk on the dry part straight away.
Other activity types in TILOS
The triangle is one of several display types. Each one draws a different shape around the activity line to show which part of the time-distance chart is busy. You choose them all in the same place: Display tab, then Activity Type.
The blue line is the activity; the shaded area is what it blocks for other work.
| Type | What it shows | Simple example |
|---|---|---|
| Simple line | The default. Where the crew is at each moment; nothing else is blocked | A kerb-laying crew moving steadily along the road |
| Rectangle | A whole stretch is busy for the whole duration | Building a bridge between km 3.2 and km 3.4 over 6 weeks |
| Triangle lower | Area reserved before the crew arrives at each point | Setting up traffic management ahead of resurfacing |
| Triangle upper | Area blocked after the crew has passed each point | Concrete curing behind the pour |
| Parallelogram (time) | The line widened in time: each point is busy for a set time before and after the crew passes | A rolling lane closure put up just before the works and removed just after |
| Parallelogram (distance) | The line widened in distance: the crew takes up a length of route ahead of and behind its position | A paving train or track renewal machine several hundred metres long |
| Parallelogram (working time / calendar time) | A blocked period at the start or end of the line, counted in working days or calendar days | Calendar time for curing, which carries on at weekends; working time for a lag that only runs on shift days |
| Stairs | The line drawn as steps of a set length | Work done in fixed sections, such as 100 m of pipe laid and backfilled at a time |
| Milestone | A symbol at a single point in time | Road opening, possession start, handover |
Back to the corridor analogy: the simple line is the cleaner walking along. A rectangle is a room closed for cleaning. A triangle is the wet floor that follows the cleaner. A parallelogram is the cleaning trolley, which takes up a fixed length (distance) or stays at each spot for a fixed time (time). Stairs are cleaning one section at a time, and a milestone is the moment the corridor reopens.
The exact list can vary by TILOS version, so check the Activity Type drop-down in your copy.
Typical beginner mistakes
- Choosing upper when lower was needed. Ask yourself whether the area is blocked before the crew arrives or after it has left.
- Thinking the triangle changes the duration. Only the activity line drives the schedule. The triangle is a visual reservation of space.
- Leaving the lags at zero. This usually makes the blocked area too small to be useful.
