Flood depth markers

Submitted: Friday, Oct 31, 2014 at 08:52
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Having just returned from an 18,000km trip to the northern end of that big hunk of dirt that stops the NT & SA from blowing away (oops) I can now reflect on aspects of the trip. One such item of interest is the use & placement of roadside advisory signs.
We came across a number of speed advisory signs that didn't make sense, to us at least. A slight bend on bitumen that had a speed advisory sign of 70km..now this corner was so slight it could have been traversed at 90/100km in the wet with complete safety but a little further along a bend that tightened up considerably & in the wet would have been a handful at 60km had no sign. I guess the local/state engineers have guides to refer to but the consistency often seems hard to fathom.
Flood depth indicators are a real case in point. Some are placed in the middle or near by of the bridges/culverts/floodways, others at the entrance to the bridge/culvert/floodway & others are marked "deepest point" which is the one I prefer. We took a photo of one floodway with it's marker on the entrance & by line of sight to the base of the marker on the other side estimated the deepest point to be at least 500mm below the base of the markers at the entrance. This could have a profound effect on the safe crossing of this floodway by a motorist.
Is this type of advisory signage supposed to be uniform across all borders & if not maybe it should.
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Reply By: Member - Rosss - Friday, Oct 31, 2014 at 09:29

Friday, Oct 31, 2014 at 09:29
Back in the 70's and 80's when we were playing with cars we had a formula for all the advisory speed signs, Double it and add 10, but they seem to have the limits a bit tighter now because even with the handling of todays cars you wouldn't get around them.
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Reply By: Member - Alan H (QLD) - Friday, Oct 31, 2014 at 09:40

Friday, Oct 31, 2014 at 09:40
We have seen ideal flood signs but can't quite remember where and are very rare.
What was used was depth marks painted on the road so that when the waters edge touched a certain mark on the road you knew exactly the depth at the deepest point of the crossing ahead of you. This way you did not have to drive into a flooded crossing to reach the flood sign to see how deep it was.

Understand it is slightly more work than just putting in a couple of posts but surveying equipment these days should make this simple task.

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Follow Up By: Member - Munji - Friday, Oct 31, 2014 at 12:58

Friday, Oct 31, 2014 at 12:58

Any chance you could research this further, since you made the observation, and get back to us all so we can go on our next trip full of understanding of the markers etc
Thanks in advance
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Follow Up By: OBJ - Friday, Oct 31, 2014 at 13:07

Friday, Oct 31, 2014 at 13:07
There are such road markings at Silverton, out of Broken Hill NSW. As you come past the Penrose Park turnoff, the road dips (floodway, I think), and the depth is painted there. Or it was when I was there about 2 years ago.
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Follow Up By: allein m - Friday, Oct 31, 2014 at 16:15

Friday, Oct 31, 2014 at 16:15
The one at Silverton was over 5 feet couple of years ago and some local detectives in a brand new Mitsubishi Pajero decided to try there luck crossing it

they were lucky to get out of the windows before the car was washed away
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Reply By: Member - Laurie K (WA) - Friday, Oct 31, 2014 at 13:02

Friday, Oct 31, 2014 at 13:02
It would be interesting to know the depths written on the markers ….. eg, if the lowest depth marked is 1 metre, then the the deepest part of the road ahead of you is going to be presumably 1 metre lower than that.

I think :-)

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Reply By: Steve in Kakadu - Friday, Oct 31, 2014 at 13:17

Friday, Oct 31, 2014 at 13:17
If I get what you are saying, I think if you look at the photo you will see that the depth mark on the marker at either end of the flood way will read the depth in the middle of the floodway at road level.

For example if the middle of the flood way is 1 metre deeper than the road markers at each end, the level at either end will start at 1 metre at ground level giving you the deepest point of the flood way.
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Follow Up By: Member - batsy - Friday, Oct 31, 2014 at 14:41

Friday, Oct 31, 2014 at 14:41
Steve, the post had .2m on the bottom which was about 100mm above the ground. The depth at the deepest point would then have been at least 500mm lower.
Discussing this topic with a today he suggested that it was not unrealistic that the sign/signs had been interfered with. I think that may be possible in the odd case but highly unlikely in most instances.
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Reply By: Ron N - Friday, Oct 31, 2014 at 13:59

Friday, Oct 31, 2014 at 13:59
All road signs are nothing more than "advisory signs" - and the information provided is to be taken with a grain of salt - as the installation of said signs is usually down to the skills of the lowest IQ roadworks employee.

We were running my 100 tonne float from Brisbane to Kalgoorlie with a 75 tonne Cat excavator on board in the early 1990's. We had sheafs of permits, instructions, and detailed itemisations of every bridge, every potential obstruction, and the precise routes, as part of the deal.

We were running over height at 4.7M and I was escorting as we left Forbes. Suddenly a steel bridge with overhead trusses loomed into view, with a sign stating "Max height - 4.6M".
I yelled over the 2 way for my driver to pull up, fast! - as confusion reigned supreme in my mind. We had permits to pass through this bridge! - yet there was inadequate clearance!

Cursing the DMR of NSW, and their disorganisation, we realised we could pull a guard off the roof-mounted airconditioner, lower the float height on the suspension hydraulics, and gain the necessary clearance to squeeze under the 4.6M clearance.

We spent a good half-hour doing this, and then jumped in our vehicles and sneaked forward cautiously to see if we were going to fit.
To our utter chagrin, the clearance between the excavator roof and the trusses, was about .8 of a metre!!
The bridge clearance was more like 5.3M, rather than the 4.6M advertised!!

Since that day, I have always taken every road advisory signpost, depth gauge, height indicator, and speed advisory sign on curves, with a very large dose of salt. Some are downright dangerous, some are downright laughable.

Cheers, Ron.
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Follow Up By: Allan B (Member, SunCoast) - Friday, Oct 31, 2014 at 19:17

Friday, Oct 31, 2014 at 19:17
Ron, I have always understood that a sign declaring "Maximum Height - 4.6m" meant that it was the highest load that could safely pass, and that the actual clearance was some nominal amount above i.e. 5.3m.

If they said "Maximum Height - 5.3m" when the actual clearance was 5.3m some fools with a 5.3m load would proceed, with dramatic outcomes. Mind you, that still happens occasionally at a bridge under a rail line at Palmwoods near here. And elsewhere too!

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Follow Up By: Allan B (Member, SunCoast) - Friday, Oct 31, 2014 at 20:37

Friday, Oct 31, 2014 at 20:37
Actually Ron, I just took a look and the bridges around here have a sign "Clearance x.x Metres" whatever that means in real terms. But I would expect it to mean that a vehicle of x.x metres height could safely pass under the bridge.

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Follow Up By: Ron N - Saturday, Nov 01, 2014 at 02:44

Saturday, Nov 01, 2014 at 02:44
Allan - Yes, it appears that the old signage indicating "maximum headroom" is being standardised Australia-wide simply with "clearance" and the figure for the maximum vehicle height that can safely fit under.

However, even that system can become confusing as quite a number of bridges are slanted, with less clearance one side than the other.
I'd presume the authorities are operating on the basis of the lowest height clearance available.

In my case with the bridge at Forbes, the issue was that we were 4.7M high and we had been given full permission to proceed under the bridge, but it initially appeared that there was 100mm less height clearance than we had been authorised to travel at.
As you say, the clearance measurement and the actual height measurement could quite often likely be at substantial variance.

Cheers, Ron.
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Follow Up By: Member - Bruce C (NSW) - Saturday, Nov 01, 2014 at 09:56

Saturday, Nov 01, 2014 at 09:56
On the subject of bridges.

Another issue is where the road surface has been built up due to re surfacing and no one has remembered to replace the sign with the new dimensions.

Does not happen, I hear you say. Think again.

There is one famous bridge down near Melbourne which has caught many an unwary traveler heading for the Tasmanian ferry.

A chap I came across tried to take his 5th wheeler under it and shaved the top off the fifth wheeler. Yes his mind was elsewhere at the time, however a fellow whose position shall remain nameless said that a few weeks previously a brand new police communications unit had done exactly the same thing writing off about $300 dollars worth.

The chap said that it seems the road had been resurfaced many times but no one thought to make up a new sign indicating the new reduced height.

The thing that annoys me a lot of the time is that an important road sign has been erected but a bush has been allowed to grow in front of it and so it obscures the sign.
I see it all the time when traveling the Pacific highway from Coffs south to Newcastle.

The simple, inexpensive fix does not seem to be of any importance. In such cases why bother to put up the signage in the first place.

I was once fined (1973) for going through a stop sign which was obscured by a branch of a tree. I could have gotten off I think but it would have cost me more to attend the court in Newcastle as I lived in Sydney. The copper was hiding in the park opposite the offending stop sign so he was more than well aware of the problem but used it to his advantage. It was a rainy night with street lights reflecting off the wet road and also reflecting off the leaves on the branches, making visibility of that sign and road markings virtually impossible.

I did not see the stop sign until the white bar painted on the road went under the front of the car. I was looking for road signage at the time and therefore would have seen it were it visible.

I started to explain to the copper and then thought and said "Ah what's the use". He was obviously getting his quota for the night otherwise he would have strolled over and broken the branch off and the community would have been done a valuable service.

It would have taken many months if not a year for that branch to obscure that sign so there was plenty of time for someone to fix the problem. Why didn't the police make the council fix it, is my question.

Cheers, Bruce.
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Follow Up By: Member - Bruce C (NSW) - Saturday, Nov 01, 2014 at 14:56

Saturday, Nov 01, 2014 at 14:56
I meant to say $300,000 worth of Communications Vehicle.
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Reply By: The Bantam - Friday, Oct 31, 2014 at 14:46

Friday, Oct 31, 2014 at 14:46
There is a document that is an obligatory standard......"The uniform code of traffic signage", no I don't have a copy.

All signage and road markings are suposed to conform to this code......hmmm yeh...good luck with that.

Its not a new issue, that outsde of the big cities sign mantenance and complinace is a bit....um....variable....but in these days of cost cutting, its hardly surprising that some signs may not be ....accurate.

Another interesting fact is that there are a whole pile of "requirements" that apply to roads and all about them that did not apply in the past.

SO..here we are traveing along a road that was built under the old regs largely unchamged since the 70's give or tale the odd guide post replacement and slash of spray seal............yeh that is Ok I supose.....200meters down the road, there was some sort of damage that meant the road had to be rebuilt......and to current standards.......so you end up with this section of road in the middle of nowhere that has guard rails, wider verges and enough butimen to mark a continuous white line down both sides as well as a line of dots up the middle.

rebuilt sections of roads may also have signs that where errected under the current rules and regulations..where those sections either side may have signs errected under the old rules...and will be maintained under those rules till the road is "substantially rebult".

On the matter of flooding depth.......say there is a crossing that is exactly as discribed on the signs......beauty.

NOW some sort of damage occurs in the wet season....after the waters have gone down a bit.........the hard working council crew goes out and patches up as best they can with the materials they carried 136Km from town pluss anything they found on site....while keeping an eye out for happy & snappy the local crocks..........and remembering there is a whole line of people wanting to get to where ever they have not been for 12 weeks

The road surface may not be perfectly aligned with what was there in the past and they may have neither the time nor the materials on hand to update all the depth markers on the whole crossing.
Don't worry, it will wash away next wet season and they will fix it again....they might bring an extra truck load of rock this time.

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Follow Up By: Alloy c/t - Saturday, Nov 01, 2014 at 10:20

Saturday, Nov 01, 2014 at 10:20
It is actually the 'Manual for Uniform Traffic Control Devices' and it runs to several hundred pages and generally has several amendments added every year ,it is the 'bible' that traffic control personnel are required to use when putting out their signage , trouble is that it is impossible in a lot of cases to actually place the signage according to the bible due to geographic and flora intrusions.
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Follow Up By: The Bantam - Saturday, Nov 01, 2014 at 11:16

Saturday, Nov 01, 2014 at 11:16
Like most things they probably changed the name while I was not watching to align with international standards or because the line markers complained that they where being discriminated against.


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Reply By: Member - Scott M (NSW) - Friday, Oct 31, 2014 at 18:06

Friday, Oct 31, 2014 at 18:06
My experience .... it pays not to ignore those little red flags on sticks up around the corner country - or the "obstruction ahead" signs - they can mean anything - in the main benign, however the odd one is a doozy - like washout and no shoulder on the road.......
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Follow Up By: MUZBRY- Life member(Vic) - Saturday, Nov 01, 2014 at 09:08

Saturday, Nov 01, 2014 at 09:08
Gday Scott
I saw those little red flags on the Merty Merty rd in September. Well worth taking note of as there are big holes in the road.
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