Static vs Mobile vs STLI: Choosing the Right Method for Temporary Traffic Management

Introduction

Choosing the right TTM method isn’t just about preference — it’s about matching method to risk.

AGTTM defines three core categories for worksites:

• Static (longer duration, fixed work zones)

• Mobile (moving or rolling works)

• Short-Term Low-Impact (STLI) (brief, low-risk activities)

Each has different device, control, and documentation requirements.

Using the wrong one can lead to serious safety breaches and audit issues.

Static Worksites

Used when:

• The worksite is fixed for a prolonged time

• Devices remain in place without needing frequent relocation

• The setup involves lane closures, barrier systems, or complex staging

Common examples:

• Road resurfacing

• Signal upgrades

• Excavation

Key requirements:

• Full TMP and TGS

• Device spacing and tapers based on AGTTM Part 3

• Worker protection through engineering or administration

Reference: AGTTM03-21, Section 2.3

Mobile Works

Used when:

• Works move progressively or repeatedly (e.g. 50–200m intervals)

• Workers or plant are exposed to live traffic over a wide area

• Constant relocation of devices would be inefficient

Common examples:

• Line marking

• Guardrail maintenance

• Shoulder sweeping

Key requirements:

• Vehicle-mounted warning devices

• Rear protection (tail vehicle or TMA)

• Advance warning strategies

Reference: AGTTM04-21, Section 2.1

Short-Term Low-Impact (STLI)

Used when:

• The job is brief (typically <1 hour)

• The work is low-risk and outside the live lane

• Workers can self-manage controls (e.g. lookouts, flashing lights)

Common examples:

• Inspections

• Graffiti removal

• Sign cleaning

Key requirements:

• Risk assessment still required

• TMP must specify use of STLI

• Controls must match site risk, not job type

Reference: AGTTM05-21, Clause 2.2

Common Mistakes

• Applying STLI to live lane works

• Using mobile layouts without enough tail protection

• Treating static works as mobile to avoid setup effort

These errors are frequently cited during compliance reviews.

Real-World Tip

If you’re unsure which method applies, ask:

• Will workers remain in one spot for 30+ minutes? → Static

• Is the work moving and visible from afar? → Mobile

• Is it brief, low-risk, and off-road? → STLI

Still not sure? Document the risk and justify your choice in the TMP.

Final Word

The method you choose affects everything: devices, layout, planning level, and safety outcomes.

Start with risk. Choose the method. Then design around it.

Not the other way around.