3. Crash test configurations

Global NCAP's star rating is not derived from a single crash. It is assembled from a small family of test configurations, each of which loads the occupant compartment in a fundamentally different way. A vehicle that performs well in a frontal offset test may still expose serious head and thorax injury risk in a side pole impact, and vice versa. Understanding what each configuration actually measures — the barrier geometry, the impact velocity, the dummy seating position, and the injury metrics that feed the scorecard — is the prerequisite for reading any Global NCAP result sheet intelligently.

This chapter examines the three configurations that dominate the Global NCAP protocol: the 64 km/h frontal offset deformable barrier (ODB) test, the 50 km/h side impact moving deformable barrier (MDB) test, and the 29 km/h side pole test. For each, we look at the physical setup, the reference frame used for measurements, the dummy instrumentation, and the specific injury criteria that flow into the scorecard.

Reference Frame and Sign Conventions

Before comparing configurations, fix the coordinate convention used throughout this course. The vehicle coordinate system is ISO 4130: X positive forward (toward the front of the vehicle), Y positive to the left, Z positive upward, with the origin at the vehicle's mid-point at ground level. Occupant injury metrics are reported in the dummy's own local frame, but for the purposes of this chapter all impact directions are described in the vehicle frame. A "frontal" impact therefore means the barrier approaches along −X relative to the vehicle; a "near-side" side impact means the barrier approaches along +Y (striking the driver's side in a left-hand-drive vehicle).

Frontal Offset Deformable Barrier (ODB) Test

The ODB test is the anchor of the frontal assessment. The vehicle is driven at 64 ± 1 km/h into a deformable barrier that covers 40% of the vehicle width on the driver's side. The barrier itself is a honeycomb aluminium block mounted on a rigid backing, and its crush behaviour is calibrated so that the energy absorbed by the barrier is repeatable across laboratories. The 40% overlap is deliberate: it concentrates loading on one longitudinal member while leaving the other largely unloaded, producing a yawing, asymmetric deceleration that is far more demanding on the restraint system than a full-width rigid barrier.

The vehicle carries two Hybrid III 50th-percentile male dummies, one in the driver's seat and one in the front passenger seat, restrained by the production seat belts and, where fitted, production airbags. Instrumentation includes head accelerometers (tri-axial), neck load cells, chest deflection potentiometers, and femur load cells. The key injury criteria reported are:

• HIC15 — Head Injury Criterion over a 15 ms window, derived from the resultant head acceleration.
• Neck Nij — combined axial force and bending moment, normalised against injury assessment reference values (IARVs).
• Chest deflection — in millimetres, compared against the dummy-specific limit.
• Femur force — axial compression in kN, per leg.

Each criterion is normalised to its IARV to produce a value where 1.0 equals the reference threshold. The scorecard then maps these normalised values to a point score. A common failure mode in the ODB test is footwell intrusion: if the toe pan collapses rearward, the dummy's lower legs are loaded and femur forces rise even when the upper body is well restrained. When reviewing an ODB result, always check the intrusion measurements alongside the dummy readings — a low HIC with high femur force usually points to structural, not restraint, deficiency.

Side Impact Moving Deformable Barrier (MDB) Test

The side impact test uses a different logic entirely. Here the vehicle is stationary and a moving deformable barrier is propelled into the driver's side at 50 km/h. The MDB has a deformable face made of honeycomb, and its mass and geometry are specified so that the kinetic energy delivered to the vehicle side structure is representative of a typical passenger car striking the door. The barrier's centreline is aligned with the vehicle's R-point (the seating reference point), which places the impact energy directly at occupant chest height.

The critical difference from the frontal test is the absence of a crumple zone. The distance between the outer door skin and the occupant's thorax is typically 150–250 mm, and the door trim, armrest, and inner panel must absorb the barrier's energy before it reaches the dummy. This is why side impact results are dominated by the performance of the side structure, the door trim, and — where fitted — side airbags and curtain airbags.

The dummy in the driver's seat is a WorldSID 50th-percentile male in current Global NCAP protocols, replacing the older EuroSID-2 in many applications. WorldSID provides more biofidelic rib deflection measurement and reports:

• Head HIC36 and resultant head acceleration.
• Thorax rib deflection — measured at multiple rib levels, reported as the maximum deflection in mm.
• Abdomen force — peak force in kN.
• Pelvis force — peak force in kN.

A frequent diagnostic pattern in MDB tests is high thorax deflection with acceptable head and pelvis readings. This indicates that the side structure is deforming into the occupant's chest — often because the door beam is too low or the trim is too stiff — while the head is protected by the curtain airbag. The remedy is structural (raising or reinforcing the door beam, softening the armrest) rather than restraint-based.

Side Pole Test

The pole test is the most localised and arguably the most severe side configuration. The vehicle is propelled sideways at 29 km/h into a rigid pole of 254 mm diameter, with the pole aligned to the driver's head position (the R-point plus a defined offset). Because the pole is narrow and rigid, it concentrates force over a small area of the door and B-pillar, producing a deep, localised intrusion that can reach the occupant's head even in vehicles with curtain airbags.

The pole test is specifically designed to evaluate head protection in far-side and near-side oblique loading, and it is the configuration most likely to expose deficiencies in curtain airbag coverage, B-pillar trim stiffness, and the interaction between the seat and the side structure. The dummy is again a WorldSID, and the reported metrics are the same as the MDB test, with particular weight placed on head HIC and thorax deflection.

Because the pole is rigid, there is no barrier crush to absorb energy — all deformation is in the vehicle. This makes the pole test a direct probe of the vehicle's side structural integrity at head height. A vehicle that passes the MDB test but fails the pole test typically has adequate lower side structure but insufficient upper side structure or curtain airbag coverage.

How the Three Configurations Combine in the Scorecard

The three configurations are not scored in isolation. Global NCAP aggregates them into a single star rating, but the weighting and the pass/fail logic differ by protocol version. In the current protocol, the frontal ODB test contributes the largest share of the adult occupant score, the MDB test contributes a substantial secondary share, and the pole test acts as a gate: a poor pole result can cap the overall star rating even if the frontal and MDB scores are strong. This gating logic reflects the real-world severity of pole impacts and prevents manufacturers from optimising for the more forgiving MDB configuration.

When reading a scorecard, the practical workflow is therefore:

1. Check the pole test result first — it sets the ceiling on the achievable rating.
2. Review the ODB result for structural intrusion and femur loading, which indicate whether the front-end structure is doing its job.
3. Review the MDB result for thorax deflection, which indicates whether the side structure and trim are adequately tuned.
4. Cross-check the dummy type and protocol version, because WorldSID and EuroSID results are not directly comparable.

Practical Verification: Reading a Test Report

Suppose you are handed a test report for a vehicle and asked to verify that the three configurations were executed correctly. The checks are concrete and reproducible:

• ODB: confirm impact speed 64 ± 1 km/h, overlap 40% ± 20 mm, barrier certification within validity, and post-test barrier crush depth recorded. Verify that both driver and passenger dummies are Hybrid III 50th male and that HIC15, Nij, chest deflection, and femur forces are reported per side.
• MDB: confirm impact speed 50 ± 1 km/h, barrier face alignment to the R-point within tolerance, and that the dummy is WorldSID 50th male. Check that rib deflection is reported at the correct rib levels and that abdomen and pelvis forces are included.
• Pole: confirm impact speed 29 ± 1 km/h, pole diameter 254 mm, and pole alignment to the driver head position. Verify that head HIC and thorax deflection are reported and that curtain airbag deployment is documented.

A common failure symptom during verification is a report that lists HIC and chest deflection but omits femur force or abdomen force. This usually means the dummy was not fully instrumented, and the result should be treated as incomplete rather than as a pass. Another symptom is a barrier crush depth that is inconsistent with the recorded impact speed — this points to a barrier calibration issue and warrants a laboratory audit before the result is accepted.

With the three configurations clearly separated in terms of geometry, velocity, dummy type, and dominant injury metric, the next step is to understand how each metric is normalised and converted into points. That conversion is the subject of the following chapter on injury criteria and scorecard arithmetic.