DT
And sorry, really naive question – how does light, or too much light, presumably, affect fish?
JG
Supposedly, if the light penetrates the water, it creates a barrier. The fish will see that as a barrier and will not want to go through and under the bridges. And with some of these, particularly in the shallows, it's their spawning route. And so, if you put a barrier of light there, they won't spawn the way they would normally spawn.
DT
Oh, right.
JG
And you can interfere with the whole breeding cycle of the fish. It's incredible, this side of things. It's not just lighting. We were very, very conscious that we didn't want to disturb the patterns of what was spawning, and just the way they migrate and use a river. So, we've been very careful not to put light into the river.
DT
And you did a luminance study before all of this; what did that inform you? What was its chief finding?
JG
Well, when we started out, we wanted it to be sensory; we wanted to make sure that the lighting fitted, or the brightness of the bridges fitted, within the surroundings. And at that time, we had no real references, or reference information to work with. So, we did the survey, which was basically surveying the brightness of the banks from one end to the other, of where the bridges were going to be. That enabled us then to know how bright all the surroundings are, how bright the landmark buildings like St. Paul's and Palace of Westminster are. We were then able to set a target so that we could say that if we lit our bridge to a certain luminance, you'd be able to see it against this background, but it wouldn't be so bright that you’d overpower the surroundings or, more importantly, you don't overpower any of these landmarks that are so important to London.
Image: Golden Jubilee Footbridges - Illuminated River © Jason Hawkes