5Technical specifications#
This section provides technical specifications in the following areas:
- 1.Host vehicle.
- 2.Impact Attenuator Unit certification.
- 3.Truck Mounted Impact Attenuator unit.
- 4.Trailer Mounted Impact Attenuator unit.
- 5.TMA repairs, modifications and inspections.
- 6.Traffic control devices.
5.1Host vehicle#
This section provides standard functional specifications for the host vehicle. This includes areas such as seating, seatbelt harnesses, masts, visibility of the host vehicle and standard control panel arrangement.
Individual state or territory authorities may have different or specific registration requirements; therefore, it is advisable that the relevant authorities be contacted prior to modifications being made to any vehicles.
The host vehicle shall conform to the following requirements:
- a)Must comply with the applicable regulatory requirements, such as Australian Design Rules, registration requirements and applicable legislation, including the Transport Operations (Road Use Management – Vehicle Standards and Safety) Regulation 2010. In some cases, a full engineering analysis by a suitable qualified person, supported by testing where applicable, will be necessary before the modified vehicle is accepted. This testing may include determination of front axle loading when the impact attenuator unit is deployed.
- b)Be approved for on road use.
- c)Be a minimum of 15 tonnes GVM (refer to Appendix A of this chapter and use of truck and trailer mounted attenuators (TMAs) at roadworks).
- d)Be a single cab truck with an automatic transmission.
- e)The mounting of any fixtures is to be engineered to 20 times the weight of the fixture.
- f)Be fitted with an Automatic Impact Brake (AIB) system that, in the event of an impact with the rear of the Impact Attenuator Unit, will apply the brakes of the TMA host vehicle automatically. In the event of such incidents, it is critical to have an isolation switch or system which will allow the AIB system to be deactivated: this will allow for the impacted TMA vehicle to be removed from positions or locations that could cause an unnecessary obstruction or blockage to the roadway. As a minimum, the AIB System must apply the brakes on all wheels of the rear axle/s of the host vehicle. The AIB system must only be activated when the Impact Attenuator Unit is fully deployed, and the host vehicle speed is no greater than 40 km/h. It is recommended that the AIB system be fitted so activation of the system is automatic when the Impact Attenuator Unit is fully deployed, and the host vehicle is travelling at a speed no greater than 40 km/h.
- g)Be fitted with an AS/NZS 4192 Illuminated flashing arrow signs approved size ‘C’ arrow board. The arrow board assembly shall be positioned on the truck in accordance with the requirements of the Queensland MUTCD Part 3 and QGTTM.
- h)The arrow board and its mountings shall be engineered to a standard:
- i.that will allow for them to withstand the forces applied during forward travel motion based on maximum speed environment for heavy vehicles when travelling to site; that is, 100 km/h, and
- ii.to withstand a force of 20 times the total mass of the arrow board and its mountings, and
- iii.if the arrow board assembly is designed to lift and lower, it must lift or lower within 15 seconds.
- i)Have an ‘in cabin’ control panel placed in close proximity to the operator and illuminated at night. The panel shall include methods of control for, but not limited to, the following:
- i.activation of communication equipment
- ii.activation of warning lights
- iii.activation of arrow board
- iv.raising and lowering of arrow board if applicable
- v.activation of rear-view camera
- vi.raising and lowering of the Impact Attenuator Unit.
- j)Be fitted with an approved four-point harness seat belts and mountings (a four-point harness seat belt is also required in the passenger seat if the vehicle is used for training or assessment purposes).
- k)Prevention of rearward seat collapse. To reduce the likelihood of rearward seat collapse in the event of a substantial rear impact: The driver’s seat and seat mountings must be of sufficient strength to prevent rearward seat collapse when subjected to a loading of 740 ± 20 daN (daN – decanewton, a metric unit of force equal to 10 newtons), supplemented by a force equal to 6.6 times the mass of the complete seat, or An engineered and certified device designed to restrict rearward seat collapse when the driver’s seat and seat mountings are subjected to the loading described in this point l) must be installed behind the driver’s seat. Reference Appendix B of this chapter for further information on rearward seat collapse.
- l)Be fitted with high strength headboards to prevent debris from crashing through the cabin in the event of an impact. The backs of these headboards are to be blacked out, so as to contrast / highlight the arrow board and other detailing of the vehicle when viewed from the rear.
- m)Be fitted with a minimum of two flashing yellow lamps, positioned on the vehicle in accordance with the requirements of the Queensland MUTCD Part 3 and QGTTM.
- n)Have mounting facilities for signs to be mounted to the tailgate or headboard as required by relevant state / territory road authority technical publications.
- o)As a minimum, be fitted with communication equipment that will enable simultaneous and independent communication to all relevant personnel, for example, two 5-watt 41 channel UHF radios, operating on separate channels.
- p)Be equipped with a warning device of sufficient intensity and volume to be easily heard by workers carrying out their normal duties at least 30 metres from the TMA.
5.2Impact attenuator unit testing requirements#
Impact attenuators units shall meet all mandatory testing requirements of the following:
- AASHTO Manual for Assessing Safety Hardware for all other Impact Attenuator Units (MASH).
Typical form of evidence for compliance would be or may include test specification report of that particular make and model.
5.3Impact attenuator unit test level ratings#
The following table indicates impact attenuator unit ratings.
| Rating | Speed |
|---|---|
| TL2 | 70 km/h |
| TL3 | 100 km/h |
Impact attenuators units shall have their test level rating clearly displayed on both side panels of the unit. The display shall be made up of a panel with black lettering (for example, TL3) on a white 210 mm x 300 mm background.
5.4Truck mounted impact attenuator unit#
Host vehicle shall be as detailed in Section 6.1 of this chapter:
- a)Impact attenuator units shall be assembled and fitted to the host vehicle in accordance with the manufacturer’s specifications.
- b)Flashing yellow light/s shall be fitted to the rear of the impact attenuator unit.
- c)The rear surface of the impact attenuator unit when deployed shall consist of Class 400 retroreflective red diagonal striping at least 100 mm wide on a white non retroreflective background.
5.4.1Truck mounted impact attenuator unit configuration#
In addition to these requirements, the following shall apply:
- a)dedicated yellow flashing light to automatically provide notice of the impact attenuator unit being raised or lowered
- b)automatic impact brake micro switch is to be fitted to the rear of the impact attenuator unit to activate the host vehicle brakes in the event of an impact
- c)in-cabin and external audible alarms to automatically provide notice of the impact attenuator unit being raised or lowered
- d)travel lock system installed that prevents inadvertent deployment of the impact attenuator unit, and
- e)when not deployed, an adhesive type (black on yellow) warning sign stating: ‘Caution: keep clear this unit may lower at any time’ must be visible from the rear of the impact attenuator unit.
5.5Trailer mounted impact attenuator unit#
Trailer mounted impact attenuator units must be equipped with anti-rotational damper systems (designed to restrict gating of the unit into adjacent traffic lanes). Breakaway cables shall also be used to ensure that the electronic braking system is activated, should the anti-rotational damper system fail. The minimum recommended weight for the tow or host truck is 4536 kg gross vehicle weight (GVM). It is important to note that, as the weight of the support or host truck is increased, the ‘roll ahead distance’ upon impact is reduced.
5.6Truck mounted attenuator repairs, modifications and inspections#
- a)All repairs and/or modifications to TMAs and attachments shall be carried out by a competent person.
- b)Following repair or modification, TMAs and attachments must be inspected and have certification documentation prepared by a competent person.
- c)TMAs and attachments must be inspected at least once each year and have certification documentation prepared by a competent person.
5.7Traffic control devices#
All traffic control devices are to conform to the requirements of and installed in accordance with the Queensland MUTCD Part 3 and QGTTM.
5.7.1Vehicle mounted signs and devices#
All vehicle mounted warning devices shall be in accordance with the requirements contained in the Queensland MUTCD Part 3 and QGTTM. This includes all signs, illuminated flashing arrow sign and flashing yellow lamps:
- illuminated flashing arrow sign
- flashing yellow lamps may be used in conjunction with this sign, provided that the lamps are either appropriately shielded or laterally or vertically displaced from the edge of the sign to avoid visually corrupting the arrow shape or its directional effect
- variable message sign
- all variable message sign boards shown in the Traffic Guidance Schemes and used in conjunction with attenuator operations as a minimum shall:
- meet AS 4852.2
- have a display of 1600 mm wide x 1150 mm high as a minimum, and
- display no more than two messages.
5.7.2Advance warning vehicles#
Advance warning vehicles warn and inform of changes to traffic conditions ahead and give motorists time to adjust their driving patterns. Advance warning vehicles shall have 'B' size arrow board or variable message board.
