What's the speed limit here? (M25/M3 junction)

[salenowon]

Coming off the M25 and onto the M3 yesterday the overhead gantry sign was indicating 40 (there were no speed restrictions on previous gantries). Immediately after the overhead gantry are fixed 50 limit signs.

I stuck to 40, assuming the gantry overruled any fixed signs. If this isn't the case surely these overhead gantry signs are completely redundant if any limit they display is immediately cancelled by the 50 limit signs?

Here's the location. You can see the 50 signs in the distance: https://www.google.com/maps/@51.3991786,-0.5390955...

Would you have stuck to 40 or assumed the limit was now 50? If it was 50, why would 40 be displayed immediately before?

[EU_Foreigner]

50 will be the limit as that is the last restriction.

[Hazuki]

I've seen the overhead gantries change whilst passing them. They don't appear to go straight to the speed restriction, they go up in stages from what I've seen.

I've witnessed them go from 40 to 50 to 60 in quick sucession (the entire gantry) with the rest following less than a second later.

[Whoozit]

40 for the 100 metres or so... probably. What were the other signs on the gantry displaying? I know that junction well.

[mudster]

Once you pass the 50 signs, the limit is 50 as others have said.

Is that gantry an old picture, as the displays appear to be MS1's, which only display an advisory limit (no red circle).

[codenamecueball]

mudster said:

Once you pass the 50 signs, the limit is 50 as others have said.

Is that gantry an old picture, as the displays appear to be MS1's, which only display an advisory limit (no red circle).

It's not clear but I can definitely make out a circle where the red LED's would come from.

[salenowon]

Whoozit said:

40 for the 100 metres or so... probably. What were the other signs on the gantry displaying? I know that junction well.

The signs might now be a newer version of those shown on streetview.

Both lanes towards Basingstoke were showing 40 (pretty sure in a circle). Nothing was showing on the London/Richmond side.

It sounds like using them for anything other than showing lane closures is fairly pointless. Surely it would have been more logical to place the gantry after the fixed 50 signs to give them greater control over what is quite a long stretch until the next gantry.

[red997]

quite often on the M25 the gantry speed limits show 40, yet less than 5 metres after are the 50 fixed 'real' signs for the road works section( Nr chorley wood)
brilliant...