Rulers on Australian roads

Generally, this issue broke our brains throughout autotravel for Western Australia.
Well, imagine you are riding on an empty asphalt road through the ideal of endless thickets of bush ... and suddenly, for no apparent reason on the side of the road is a two-meter line. Around there is no longer anything but bushes, asphalt tracks, and you have a machine of this line.
Honestly, my friends and I did not come to the correct answer for yourself, had to ask a local.
It was very unexpected ... Australia never ceases to amaze)
This line needs to measure, you will not believe the depth of the ford !!!
Yes, it is a ford. Ask where the steppe ford?
It turns out that there are sometimes flooded everything. Sometimes. Rarely. But if the river overflowing, then bottled under the full program.
Build a bridge one day no one will be in a year, so in the lowlands along the roads are such
line If the road is flooded, the line shows the mark of the deepest places.
And the drivers decide for themselves - go on, or turn around and go back many hundreds of kilometers
. As a rule, large trucks going up to one and a half meters. Sometimes tied behind a passenger car.
Buses pick up luggage in the cabin, luggage hatches open up and go - stream flows through them

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