1) Don't think I've come across any road signs in the UK that can display multiple text sizes
2) The text on the second line looks too close the the bezel of the sign for it to be displayed properly at the edges if it were real
3) The font 'Transport' appears to have been used to make it appear authentic, but in reality signs like this mostly use whatever font they are designed to work with.
4) The lettering looks a bit wobbly, which is what happens on Photoshop when you rotate text (to get the correct perspective).
5) On a busy road such as this, I'm sure a message like that would have created a bit more hype, unless it was only up for literally a couple of minutes.