Common Questions

Which is which, Concave or Convex?

Convex or Concave is always taken relative to the side that the road is to the barrier being installed.

concave

convex

What is NCHRP 350?

The United States of America has a set of tests developed as part of the National Cooperative Highway Research Program(NCHRP), published in 1993 as Report 350, “Recommended Procedures for the Safety Performance Evaluation of Highway Features” which is what has become to be known as “NCHRP 350”.

The crash test procedures required by AS/NZS 3845 are based on the Federal Highway Administration (FHWA) NCHRP 350 report. However, acceptance by the FHWA standard does not imply acceptance by Australian Road Authorities as AS 3845 requires additional aspects to be considered as well as any state Road Authorities specific requirements.

What are NCHRP350 Test Levels (TL) and what are their requirements?

Whilst AS/NZS 3845:1999 adopts the six test levels of TL1 to TL6, from NCHRP 350, it supplements them with a further test level TL0.

Test Level 0 has been discontinued as of AS/NZS 3845:2015 but is still commonly referenced during transition to this standard.

Test Levels for Longitudinal Barriers (TL- 0 to TL- 6)

Test LevelVehicle Mass (kg) and TypeSpeed (km/h)Angle (degrees)Impact Severity (kJ)
0*820 C50209.3
1,600 C5025
1820 C50209.3
2,000 P502534.5
2820 C702018.1
2,000 P702567.5
3820 C1002037.0
2,000 P10025137.8
4820 C1002037.0
8,000 S8015132.3
5820 C1002037.0
36,000 V8015595.4
6820 C1002037.0
36,000 T8015595.4

(Source: AS/NZS 3845:1999 and 3845.1:2015)

LEGEND:
C = small car
P = four wheel drive or utility truck
S = single-unit truck
T = tanker type semi-trailer
V = van type semi-trailer

NOTES:
  1. Refer NCHRP 350 (1993) for Test Level Procedure
  2. TL- 4 to 6: Truck and other heavy vehicles
    TL- 3: High-speed arterial roads
    TL- 2: Local and collector roads
    TL- 0 and 1: Work zones and low speed roads

What is the MASH standard?

The “Manual for Assessing Safety Hardware” (MASH) standard (Publication code MASH-1) was born after a 6 year review of the NCHRP350 standard.

It was released in 2009 by the American Association of State Highway and Transportation Official (AASHTO) and is now the basis of testing procedures for road safety barrier systems in AS/NZS 3845.1:2015.

This rewrite updated the test vehicle requirements, the impact condition criteria, and the evaluation criteria to reflect modern car fleets.

All barrier systems designed from 2011 will be crash tested to the MASH standard.

For further information on changes see FHWA Presentation on MASH (October 2009).

Will barriers require re-testing to the MASH standard?

Typically systems which had been approved to other testing standards such as NCHRP 350 do not require retesting to the criteria of MASH, but this is up to the local state Road Authority on review of their approved barrier systems.

What are MASH Test Levels (TL) and what are their requirements?

The below is the accepted MASH test level conditions and impact severities for Longitudinal barriers.

Test LevelVehicle Mass (kg) and TypeSpeed (km/h)Angle (degrees)Impact Severity (kJ)
11,100 C502518.9
2,270 P502539.1
21,100 C702537.1
2,270 P702576.6
31,100 C1002575.8
2,270 P10025156.4
41,100 C1002575.8
10,000 S9015209.3
51,100 C1002578.8
36,000 V8015595.4
61,100 C1002049.6
36,000 T8015595.4

(Source: AS/NZS 3845.1:2015)