Published: 9 December 2015 | Category: Technical advice note | Audiences: Road controlling authorities, Road traffic engineers & consultants, Roading contractors
This TAN clarifies issues related to the utilisation of concrete barriers to temporarily detain rockfall/slope debris.
Further to TAN #15-08: Road Safety Hardware Update-Temporary Concrete Barrier TCB-1, this Technical Advice Note clarifies issues related to the utilisation of concrete barriers to temporarily detain rockfall/slope debris.
Concrete barriers have been widely used to detain rockfall and slope debris as a temporary measure whilst permanent solutions are sought. The concrete barriers used take a number of forms (New Jersey Barrier/Transit F-shape concrete barrier and other) and generally have been adopted for detention due to their no longer being compliant as temporary concrete road safety barriers.
A number of operational and safety related issues have been experienced using such barriers for detention. Focusing on the Transport Agency’s adoption of Safe System thinking and focus on Zero Harm, the requirements for concrete barriers to temporarily detain rockfall/slope debris are detailed here.
Concrete barriers used to temporarily detain rockfall/slope debris shall comply with the following requirements:
Where compliance cannot be achieved a departure is required.
This change shall take effect for new installations from 1 July 2016.
Existing temporary barriers shall be replaced as and when required through degradation, damage or impact.
All non-reinforced barriers shall be replaced no later than 1 July 2016, or as soon as reasonably practicable thereafter as agreed with the RCA.
Any concrete barriers/concrete barriers with associated fencing, intended as a permanent solution, will require detailed design and approval.
To facilitate inventory control, from 1 July 2016 all units shall be identifiable and a database of their date of manufacture and source, amount and location of reinforcing, condition, date of placement in current location and inspection dates shall be maintained.
After 1 July 2016, the use of non-reinforced concrete barriers used to temporarily detain rockfall/slope debris will be considered non-compliant practice.
Contact Stuart Finlan of the Highways and Network Operations’ Structures team at stuart.finlan@nzta.govt.nz.
Kevin Reid