When you click on the calendar there is a button below for 'Full Day' that is ticked. If you then untick that you can enter a time range to view the map. Two thoughts:
Could we have a 'live' view button (to set the times for, say, the next hour). This is for when we have major works with a changing TM plan. Recently we've had resurfacing works on a major roundabout with night-time closures. The works have been done on quadrants of the roundabout, so on some days two lots of closures/diversions are showing (the first up to 06.00hrs and the second from 19.00hrs). This is, of course, confusing unless the viewer has the ability to work it through themselves.
Can the functions to change times be made more obvious? eg visible when 'today' is visible rather than have to go through the calendar and untick a box before it is available.
Those people I have shown the time range option to are always happy to find they can view works at the specific time they want to travel.