Sometimes, though, too much in-depth information is bad, and you have to moderate accordingly. This is a problem not exclusive to the BBC. Every program concerning something factual has to be balanced accordingly and this program managed to find that.
'Dumbed-down' is a subjective term used by people who disagree with the content of a program. It is neither reflective nor indicative of modern society. The program makers were well aware of the vast fount of knowledge there is out there concerning CrossRail, and they made a program which was a bite-size, easy-to-grasp for the layman (like me

) refresher, or starter, on the vast engineering feat needed to essentially 'thread' a new railway through a pre-existing metropolitan landscape. I thought adding the 'personal' touch of interviews with owners of buildings situated on the course of the railway, as well as the engineers involved (particularly those involved with the 'Eye of the Needle' section) gave the layman an insight into railway engineering. I certainly did not find it 'dumbed-down'. I found it balanced, concise and well-made.
'One of the biggest engineering projects' maybe, but if you don't add the personal touch to a program, no-one is going to care if you try and build a new Monorail above the streets of London. You go from a generic program to a more esoteric one, and that does not generate more audience figures, which is ultimately the goal of program makers.