What are these criss-cross patterns close to Cambridge Airport (UK)? To the immediate south of the runway at Cambridge airport, there are a large number of possibly-concrete things embedded in the grass.

I'm not sure whether they are have any aviation-related function, but they are mostly either parallel or perpendicular to the runway.

The question is - what are they?

Aerial view here.
In 2017 there was a major archeological dig in the area of Hatherdene Close and Coldhams Lane at the south end of the Cambridge airport.  The "criss-cross patterns" are additional exploratory trenches as part of a "Preliminary Archaeological Investigation".

Welcome
to the public consultation on the emerging development proposals for the creation of a new
neighbourhood at Land North of Cherry Hinton



Anglo-Saxon artefacts unearthed on Cambridge building site







The area is also the subject of a Planning Document. I had a quick read through the document and I found a reference to "Preliminary Archaeological Investigations", which are the trenches seen in the aerial photo.  

LAND NORTH OF CHERRY HINTON Planning Document