No Bill,
I am quoting the St Ives Park and Ride. en route to Cambridge, before the Bus route was extended to start from Peterborough, to join the Guided Bus way at St Ives.
The buses, usually double deckers, are identifiable by the guide wheels, mounted horizontally immediately behind the front wheels
We just followed the signs into the Park and Ride car park.
En route from St Ives to Cambridge, the busway does not share any public roads, but crosses several roads, with the crossings controlled by traffic lights. The bus slows on the approach, until the change to green for it.
I fear that you inadvertently strayed onto the start of the busway, rather than the entrance to the car park..
In Cambridge you also get bollards that rise out of the road, allowing only certain vehicle tom access certain areas. You cannot fail to see those since, there are at least two in each lane, and are about 100 mm diameter and at least a metre high..
Howard