MASH vs NCHRP 350: What’s the Difference for Work Zone Devices?
If you work in highway construction, traffic control, or public infrastructure, you’ve likely seen specifications referencing either NCHRP 350 or MASH. But what do these standards actually mean — and which one applies today? Understanding the difference is critical when selecting barricades, traffic drums, temporary barriers, or TMA accessories.What Was NCHRP 350?
NCHRP Report 350, published in 1993 by the National Cooperative Highway Research Program, established crash-testing standards for roadside safety hardware. It defined how devices such as guardrails, crash cushions, temporary barriers, and work zone devices were tested for vehicle impact performance. For many years, NCHRP 350 compliance was the required benchmark for:- Temporary traffic barriers
- Impact attenuators
- Truck-mounted attenuators (TMAs)
- Work zone channelizing devices
What Is MASH?
MASH stands for Manual for Assessing Safety Hardware. Published by the American Association of State Highway and Transportation Officials (AASHTO), MASH updated crash-testing criteria to reflect modern vehicles — including heavier pickup trucks and SUVs. You can review the current MASH guidelines through AASHTO’s official publication .Key Updates in MASH Testing:
- Heavier test vehicles (e.g., 5,000 lb pickup trucks)
- Revised impact angles
- Updated evaluation metrics for occupant risk
- More realistic impact conditions
MASH vs NCHRP 350: Side-by-Side Comparison
| Feature | NCHRP 350 | MASH |
|---|---|---|
| Publication Year | 1993 | 2009 (updated since) |
| Vehicle Types | Older vehicle fleet | Modern pickups & SUVs |
| Crash Realism | Pre-SUV era assumptions | Current vehicle weights & geometry |
| Current Federal Adoption | Phasing out | Required for new installations |
Is MASH Required Today?
Yes — for most federally funded highway projects. The Federal Highway Administration (FHWA) issued guidance requiring new permanent safety hardware installations to meet MASH criteria. You can review FHWA policy updates directly at: Federal Highway Administration (FHWA) Safety Hardware Memoranda However, some previously installed NCHRP 350 devices may remain in service if already approved.What This Means for Contractors & Work Zones
If you’re bidding or supplying equipment for public roadway projects, MASH compliance is increasingly required for:- Temporary concrete barriers
- Water-filled barriers
- Truck-mounted attenuators (TMAs)
- Impact attenuators
Common Misconceptions
“If it was NCHRP 350 approved, it’s still fine everywhere.”
Not necessarily. Many state DOTs now require MASH compliance for new deployments.“MASH is just a minor update.”
It represents a significant modernization of crash testing assumptions and vehicle behavior.“All traffic control devices are crash tested.”
Only certain categories (like barriers and attenuators) undergo full impact testing. Cones and standard channelizers typically follow visibility and performance standards instead.Bottom Line
NCHRP 350 laid the foundation for modern roadside safety hardware testing. MASH builds on that foundation — reflecting today’s vehicles and real-world crash conditions. If you’re supplying or installing work zone protection on public roads, assume MASH compliance will be required unless project documents state otherwise. When in doubt, confirm with the project engineer or review the state DOT specifications before deployment.Note: This article is for informational purposes only. Always consult project specifications and applicable state or federal requirements before selecting safety hardware.