If End Time is after Current Time?


I have a table we use as a dashboard in a control room,  which basically lists user entered journey info. A user logs their journey with an estimated end time. I'm trying to change the colour of an entry on the table to highlight 'overdue journeys' - ideally graded orange for say 15 mins over due and red for 30 mins overdue, but I suspect that is way off the complex scale.

I got close using 'display rules' and added a rule  of ' if [estimatedend] is [ later than current time]' then it changed the colour.. woeked perfectly, except, it needs to be other way round which you can't do... so basically every journey is red, as they will always end after current time.   So near but so far!

if the above had worked, then I considered seeing if I could add a EstimatedEnd+1 record that adds an hour to the estimated end time entered automatically, then you could use the above based on the +1 time to give a red colour an hour after. But seeing as the display rules wont work, then I guess this is not worth doing.   

thanks in advance for any thoughts.