WAS trawling the web and found this little piece of information
it is well worth having a look if you visit Holland and or pass through
depending where these zones are may effect YOU as well, link is below.
LINK
On this site is also a link which has information in english which
may be of use,
Ah, I’ve seen the signs for these, I wondered what they were, they are brand new. They have a picture of a truck on them, and they flashed a green wavy line of LEDs at me as I approached them… (in my non-compliant truck 
).
Harry Monk:
Ah, I’ve seen the signs for these, I wondered what they were, they are brand new. They have a picture of a truck on them, and they flashed a green wavy line of LEDs at me as I approached them… (in my non-compliant truck
Harry this is somthing diffrent, this means the the traffic lights ahead “should” stay green for you in busy traffic times, to save you wasting fuel and therefore saving the planet! Theres a few on the N65 between Tilburg and Den Bosch I know of.
The milieuzones are signed by a lorry ban sign (red circle, white background with a black truck) with the word “milieuzone” above it.
These milieuzones are town centre based and i know anywhere within the ring road here in Tilburg is covered, so anyone nipping through to Germany or beyond shouldnt have to worry, unless ur looking for a good bar, lol.
Live and learn, thank you!