What does this Swiss black on yellow rectangular traffic sign with a symbol looking like a dart mean?

Question

I've seen this traffic sign in Switzerland. What does the second panel from the top mean? The panel is a rectangle, maybe 1½ times wider than high, depicting on the left a symbol that looks like a dart drawn within a rhombus, and on the right the text ►1,8^m◄. The latter may indicate a maximum width but there is a different panel for that, so I expect the meaning to be a bit different.

I could not find this sign on this list of traffic signs in Switzerland and Liechtenstein.

Something is only permitted with AWD when having permission from the municipality of Ennenda, but what?

A few km away I saw the panel again, with the same symbol on the left, but on the right a maximum mass (12 t) rather than a maximum width:

Answer 1

Signals with a black border and black text on yellow ground are military signals, as defined in Art 101.8 of the Swiss Road Signal Ordenance (Signalisationsverordnung, not available in english):

Gelb-schwarze Signale, ausgenommen die Signale «Hauptstrasse» (3.03) und «Ende Hauptstrasse» (3.04), richten sich ausschliesslich an die Führer von Militärfahrzeugen.7 Die Signale haben einen gelben Grund; der Rand, die Schrift und die Symbole sind schwarz. Die Bestimmungen zum Schutze der Signale (Art. 98 SVG) sind anwendbar.

They are only valid for drivers of military vehicles while in active duty.

The meaning of these symbols is the following

^{(Image courtesy of Swiss Army Logistics Base, not available online)}

• Top left: military use [of road] allowed
• Top right: max weight 5t
• Bottom left: max width 1.8m
• Bottom right: trailer allowed

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On how to read the sign post in the first picture in general, the general rule is to read from top to bottom:

• Passage is forbidden for any motorized vehicle
• Motorized military vehicles are allowed to pass if they are less than 1.8m wide
• Permission (for civilians) to use the road with a motorized vehicle can be granted by the municipal council of Ennenda
• In any case you need an all wheel drive to use the road

Answer 2

The pictogram on the road-sign is just the symbol within the swiss armed forces for a Truck driver. That's the reason why you probably won't find it unless you know what you are looking for.

The drivers themselves will get a badge like the one below.

So this sign is an instruction for a military truck driver.