Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Understanding SAE J850: Fixed Rigid Barrier Collision Tests for Historic Reference
Introduction and Purpose
SAE J850-2015, Fixed Rigid Barrier Collision Tests, is a recommended practice that establishes standardized procedures for conducting barrier collision tests on automotive vehicles. Originally issued in 1963, this document was stabilized in 2015 and is retained for historical reference only, as it has been superseded by more representative test methods. The standard aims to ensure that test results from different facilities can be compared by defining requirements for test sites, barriers, impact conditions, and instrumentation.
⚠️ Historic Status: SAE J850 is no longer maintained for current vehicle testing. Engineers should refer to newer SAE standards for up-to-date crash test methodologies.
Key Specifications for Barrier Collision Tests
The standard outlines critical parameters for fixed rigid barrier tests. The table below summarizes the primary requirements.
| Parameter | Specification |
|---|---|
| Barrier Face | At least 3 m (10 ft) wide × 1.5 m (5 ft) high |
| Barrier Surface | Faced with 1.9 cm (0.75 in) plywood |
| Barrier Rigidity | Face motion < 1% of vehicle permanent crush |
| Impact Speed (typical) | 48 km/h (30 mph) |
| Vehicle Acceleration | Not to exceed 0.3 g |
| Lateral Alignment (flat) | ±76 mm (±3 in) |
| Lateral Alignment (pole/offset) | ±25 mm (±1 in) |
| Approach Surface | Level, paved, friction coefficient 0.7–0.8 |
Proper alignment and speed control are essential for repeatable test conditions. The barrier must be massive enough to limit motion, and the approach path must minimize uncontrolled variables.
Instrumentation Considerations and Frequently Asked Questions
Accurate measurement is critical in crash testing. SAE J850 requires instrumentation compliant with SAE J211/1 (electronic) and SAE J211/2 (photographic). Key instrumentation includes vehicle accelerometers, anthropomorphic test devices (ATDs), transducers for restraint loads, and contact recording systems.
🔍 Design Insight: The standard emphasizes that instrumentation should not introduce resonances within the frequency range of interest. Data acquisition systems must meet the stringent requirements of SAE J211 to ensure fidelity.
Frequently Asked Questions
Why is SAE J850 considered outdated for current testing?
The standard was stabilized because newer test methods better represent the impact conditions for modern vehicles on the road. SAE J850 remains useful for historical reference and understanding the evolution of crash testing.
What is the typical impact speed specified?
The standard recommends 48 km/h (30 mph) as a typical speed, but other speeds may be used for special studies.
How should the test vehicle be accelerated?
The vehicle should be accelerated at a rate not exceeding 0.3 g to avoid inertial effects influencing the vehicle attitude or occupant reactions. It should hit the barrier at essentially constant speed.
What alignment tolerances are required for the lateral impact point?
For a flat barrier, the lateral alignment should be within ±76 mm (±3 in). For pole or offset barrier fixtures, a tighter tolerance of ±25 mm (±1 in) is necessary for meaningful comparisons.
