creating our private taxi-drivers’ Knowledge
What does "in cities we negotiate our way around the landscape half-consciously creating our private taxi-drivers’ Knowledge" mean?

Context:

We learn to ‘feel’ the sky darkening before we arrive at a conscious awareness that it is going to rain; even in cities
we negotiate our way around the landscape half-consciously creating our private taxi-drivers’ Knowledge. We are born with an intuitive understanding.

Question

creating our private taxi-drivers’ Knowledge
What does "in cities we negotiate our way around the landscape half-consciously creating our private taxi-drivers’ Knowledge" mean?

Context:

We learn to ‘feel’ the sky darkening before we arrive at a conscious awareness that it is going to rain; even in cities
we negotiate our way around the landscape half-consciously creating our private taxi-drivers’ Knowledge. We are born with an intuitive understanding.

Answer

In London, black cab drivers must study and learn how to drive in the city including the shortest routes and most efficient way of getting their passengers to their destination. This is commonly referred to as "the Knowledge' - meaning knowledge of how to drive a taxi in London. Drivers must pass a test of the Knowledge before they can get their taxi licence. 
The writer is using the complex Knowledge acquired by taxi drivers as a metaphor.