NT (etc) may NEVER see speed derestriction again.
An Australian Standard, 1742.4 of 1999 effectively governs, for the States and Territories, 'what speed limit (or derestriction) signs may be used, and how they are to be placed and whatnot on the Australian road network.
In AS1742.4 of 1999 (still current) the speed derestriction sign is catalogued as an R4-2. Its meaning; "The Speed Derestriction sign shall be used where permitted by State or Territory regulations, at the end of a linnear speed zone or a general urban speed limit to indicate that no speed limit applies to the road beyond the sign".
(L, P1, P2 license holders remained speed-limited by way of "license conditions", and heavy vehicles owing 'speed limiters' and 'ARR25').
This sign, was adopted into original Australian standards from the United Nations Convention on Road Traffic, "Road Signs and Signals" portion, where it is catalogued as a C,17a - "End of all local prohibitions imposed on moving vehicles".
An update, "DR 07228" which had public comment closure 12 July 2007, which slipped under the radar, has seemingly removed any reference to the speed derestriction sign whatsoever, so it can NEVER be placed on Australian roads again. Well, that is the intention of the contributing public servants who are members of the overseeing AS committee, MS12.
http://www.saiglobal.com/shop/script/Details.asp?DocN=MSWD07228ATCRD
In effect, these employees and their academic supporters have denied elected reps from ever using the sign again.
Or so they may think, we'll see. Perhaps we'll see who really runs this country, our parliament or road agency employees.
Agency staff can take this as a warning of action to come. Not on people.
The speed derestriction sign is gone, removed. It's replacement will generally be the new-ish R4-12, END Speed limit sign". This sign has a white ground, black lettering for the English word "END", a black rim with the ceasing number in black within that circle.
The R4-12 sign shall be used typically when the road ahead is not to a high-standard. Say into a State Park etc. NSW will supplement this sign with ONE or BOTH of the following additional templates vis; "END XX - STATE LIMIT 100 APPLIES - DRIVE TO CONDITIONS"
By design, and by ARR 25, this now 8 year old sign reverts to *your jurisdictions* rural default speed-limit. The speed derestriction fell under, cheekily, ARR25 (3)(b) - another law of this jurisdiction. It's removal ceases to give legal effect where it still remains on a road. The signs, where they remain, *MUST* now be removed.
OPTION: - Might need to adopt a 'rural prima facie speed-limit of 80km/h' once again...... Because this country is PC mad, and that prima facie concept, I suggest, might actually work. Or we ban speeding fines in favour of fines for using too much fuel!
Some quoted examples of the update AS document, that is not yet rubberstamped:-
Draft for Public Comment
Australian Standard
LIABLE TO ALTERATION—DO NOT USE AS A STANDARD
BEGINNING DATE FOR COMMENT: 10 May 2007
CLOSING DATE FOR COMMENT: 12 July 2007
Manual of uniform traffic control devices
Part 4: Speed controls
(Revision of AS 1742.4—1999)
Principal variations from the 1999 edition are as follows:
(a) The Standard reflects the fact that the general urban speed limit in all states is now 50 km/h.
(b) School zones have been transferred from AS 1742.10.
(c) Shared zones have been transferred from AS 1742.13.
(d) The Speed Limit AHEAD (G9-79) sign has been added and becomes an alternative
form of buffer zone.
(e) The Derestriction sign has been deleted.
**********************************************
PREPARATION OF AUSTRALIAN STANDARDS
Australian Standards are prepared by a consensus process involving representatives
nominated by organizations drawn from all major interests associated with the subject.
Australian Standards may be derived from existing industry Standards, from established
international Standards and practices or may be developed within a Standards Australia
technical committee.
During the development process, Australian Standards are made available in draft form at
all sales offices and through affiliated overseas bodies in order that all interests concerned
with the application of a proposed Standard are given the opportunity to submit views on
the requirements to be included.
The following interests are represented on the committee responsible for this draft
Australian Standard:
ACT Department of Urban Services
ARRB Transport Research Ltd
AUSTROADS
Association of Consultants in Access Australia
Australian Automobile Association
Australian Chamber of Commerce and Industry
Australian Historic Motoring Federation
Australian Industry Group
Australian Motorcycle Council
Commonwealth Department of Transport and Regional Services
Department of Infrastructure, Energy and Resources (Tasmania)
Department of Infrastructure, Planning and Environment (NT)
Department of Transport and Urban Planning (SA)
Institute of Public Works Engineering Australia
Main Roads Department, Queensland
Main Roads Western Australia
Roadmarking Industry Association of Australia
Roads and Traffic Authority, NSW
And so goes the speed derestriction sign (//) from AUS Standards. The sign, however, remains a UN Road Traffic - 'Road Signs' usable item for those countries contracting the UN Road Traffic Convention, such as AUS, its removal from AUS Standard 1742.4 of 2008 means the derestriction sign will not be used further*.
The 'replacement' for speed derestriction, in the new Standard, is the R4-12 "END SPEED-LIMIT" sign, which by design, falls back to (defaults) to the jurisdictions rural default speed-limit. This newish sign will typically be posted at the start point on lower quality rural roads.
(*) A State government, could, if it chooses, adopt a geographical 'prima facie' rural speed limit, or other measures to implement much the same effect as derestriction. NO Standards body or public service agency can restrict that, try though such might, as we see here in this 'update'.
Pdf version of AS1742.4 of 2008 costs $84.15.