Broadcasting House, Salford Quays & TVC

This really only applies to closet switches in branch offices really (and such places do still tend to be an utter mess, mostly due to low-skilled technicians being given half a description for a given task). Modern managed services/ISP/cloud type providers are dealing with complex, shared platforms, where an error in one part of the infrastructure can have catastrophic consequences for multiple customers. Sloppiness is very much something that cannot be tolerated in such an environment; all it takes is one cable to be run to the wrong port, and depending on the configuration the entire DC (and in some cases, multiple sites) can be brought to a halt.

My racks look like a bloody tornado went off in there. One day I'll tidy them.

(lol)

Are patch bays really used any more? When I've seen them in recent installations they never seem to be used. I imagine modern routers have pretty much removed the need for them.

Although it's still good to be able to over patch a dead router to stay on the air with a key camera chain or source, but that's usually done with a secondary device, such as a relay box, or small router. It's very rare these days to totally lose all of a router, they all (should) have back up control boards. Sometimes cameras and primary sources are interleaved
across several input cards. US broadcasters like to do that I'm told ? Audio departments, particularly in the UK, still like to have acres of patching, despite modern desks having a great deal of routing functionality built in. Folk on the European mainland are a little less conservative, and often raise their eyebrows when they get inside UK sound control rooms.

The fundamental difference also is traditional broadcast kit is wired from the rear, IT kit is wired from the front. So you end up with cables all over the front of a rack. You can often mount the IT kit set back a little,
to ease that problem, but them to run into another issue, that the kit is often too deep for the rack. These days you're forced to have 1 metre deep racks really. I saw some nice racks in The Netherlands recently, they had about 200mm of space 'outside' the rack strip on each side, that allowed for cable tray etc there. All ganged together to form a cold corridor. Made by Minkels http://www.minkels.com/#

Only IT networking equipment is wired from the front, switches / routers etc. Servers and storage are all wired at the back.

Yes, fair enough, good point. Though it's switches and routers that have the 'busiest' wiring

Why do that when, as I discovered on an install last week, you can just bolt your cable tray to the rear rack strip, making it impossible to fit anything to the back.

Yes indeed, but with the wider racks I saw, you have loads of 'volume' on each side outside of the actual
rack mounting area to lose cabling. There's then no restriction of the manner you mention front or back. It is a pain when someone has done that, and you come along later and try and fit something deeper. Of course the drawback is fewer racks than usual in a given area

This was actually one of these wider racks, even had mount points at the top and bottom where you could fix a tray, but no, the IT guys had just stuck it on the rear rails.

What a difference 2 years make.

Probably already mentioned here but here's a large photogallery from TVC https://www.flickr.com/photos/rugbymadgirl/sets/72157633068277331