These days most of the employers are asking operators to go for medical test that he/she is fit to work at heights and while operating heavy goods and controlling cranes/ forklifts.
Crane/Forklift medical in your own convenient time* for bulk booking medicals can be done on your own site.
Documents requirement for D4 Test:
Medical Form (specific to your medical)
Photo ID
Your driving glasses/contact lenses & prescription
Details of any ongoing medical conditions plus any medication you are taking