What you referred to as the police post is actually an opening to give natural light. It is directly over the underpass walkway and it provides natural light to the underpass walkway. It would be great if you can stop by it one day to walk through the underpass for your viewers. Thanks.
With regards to Amasaman interchange, when you coming from Pokuase towards Nsawam, the ramp you see is the entrance ramp for the third tier interchange which would take you over the other lanes towards Amasaman township where Melcom is.