The drawing showed access.
Could the delivery vehicle actually make the turn?
A road line on a general arrangement is not a logistics release. Change four inputs, run the turn, and see where a plausible route becomes a constructability problem.
By Duc Hoang, PMP · August 2026 · 4 min read + interactive screen
The vehicle arrived on Day 9. The gate was wide enough. The internal road existed. Then the driver stopped before the first bend.
The drawing had answered a planning question: is there a route? It had not answered the field question: can this vehicle use that route with its load, clearance and turning behaviour? By then, the lifting window, escort and crew were already committed.
Access is not a line on a drawing. It is a released physical envelope.
The drawing-to-delivery gap
Composite example, not a client route. Concept screening estimate: the open calculation is the source of truth; the plan view explains it.
Clear width between hard obstructions—not the line shown on the plan.
Radius to the inside physical edge of the turn.
Illustrative overall delivery-vehicle length.
A screening allowance; it is not a project standard.
Concept screen
Screen fails
Margin -2.30 m
Loading the concept screen…
The result and assumptions remain available in the controls and metric table.
Screening result: Screen fails; margin -2.30 metres.
Geometry screen
Screen fails
- Available
- 5.50 m
- Required
- 7.80 m
- Margin
- -2.30 m
- Off-tracking
- 3.44 m
Important: This is an illustrative screening model, not a swept-path approval. A positive margin means “investigate further with project data,” not “release the delivery.”
What changed when you moved the sliders
The screen treats the vehicle as a simplified rigid envelope. Effective wheelbase is 52% of overall length; front overhang is 18%; vehicle width is fixed at 3.00 m. Those teaching assumptions are intentionally visible because a hidden vehicle library would imply precision this page does not have.
Rear wheels cut inside
Approximate off-tracking = effective wheelbase² ÷ (2 × vehicle path radius).
The body swings outside
The outside front corner adds width beyond the nominal 3.00 m vehicle body.
- Vehicle path radius
- 12.75 m
- Effective wheelbase
- 9.36 m
- Approximate off-tracking
- 3.44 m
- Approx. rear-wheel path radius
- 9.31 m
- Outside corner swing
- 0.36 m
- Working clearance
- 0.50 m each side
- Required envelope
- 7.80 m
A pass on geometry is only the first gate
The route should be owned and released like any other construction interface. “Shown on the drawing” is not acceptance evidence.
Swept path
- Verify
- Approved vehicle data and route geometry
- Acceptance evidence
- Vehicle-tracking output plus marked pinch points
- Owner
- Logistics / transport lead
Bearing capacity
- Verify
- Axle loads, pavement build-up, culverts and bridges
- Acceptance evidence
- Route bearing assessment and crossing releases
- Owner
- Civil / temporary works
Overhead clearance
- Verify
- Conductors, gates, trees, pipe racks and signage
- Acceptance evidence
- Measured clearance envelope and isolation plan
- Owner
- Electrical + logistics
Road furniture
- Verify
- Barriers, drains, poles, fences and removable items
- Acceptance evidence
- Removal / protection schedule with owners
- Owner
- Site construction
Delivery interface
- Verify
- Laydown, crane position, reversing and egress
- Acceptance evidence
- Approved delivery and lifting sequence
- Owner
- Construction + lifting
Controls
- Verify
- Permits, escorts, traffic windows and emergency access
- Acceptance evidence
- Route permit and traffic-management release
- Owner
- HSE / permits
What the plan review should ask
- Which actual vehicle and load controls the route?
- Where are the inside and outside swept-envelope pinch points?
- What changes between survey, civil completion and delivery day?
- Who signs the route release, against what dated evidence?
- What is the recovery plan if one control is false?
What this model cannot tell you
- It does not model steering geometry, articulation, axle groups or a manufacturer-specific vehicle.
- It does not assess gradients, crossfall, bearing capacity, overhead clearance or dynamic behaviour.
- It does not replace a route survey, vehicle-tracking study, temporary-works design or competent-person approval.
- It does not determine contractual responsibility, delay entitlement or cost.
Further reading
For project work, agree the representative vehicle and movement, then show wheel tracks, the vehicle-body envelope, clearances and route constraints against surveyed geometry. See the Worcestershire County Council swept-path presentation guidance and the UK Health and Safety Executive vehicle-route questions.
The schedule had already assumed the route was ready
Once geometry, structure and controls become explicit gates, they can be linked to mobilisation and delivery instead of discovered by the driver.
Open “Access Was Assumed”