Or you can do this work in code, and put a countdown timer beneath each bus time (such that you walk out the door before time expires and you will make it).
Among this is the time of civil dawn, because at this time I don't want to be riding bike anymore since it's getting dark (and colder).
Next to it is a countdown timer with an offset of minus two hours, since I do ride my bike around 1 to 1.5 hours. So when I see that this timer is reaching 0, I know that I'm at my last opportunity to go for a bike ride that day. Once it reaches 0, it shows the countdown to the correct, non-offsetted time of civil dawn, but in another color, so that I know that I still have time to make a shorter ride.
I barely look at the time of dawn, since the countdown timer is so much more informative for me. It let's me know how many hours or minutes I still have to do things.
Do you mean civil dusk?
Some years ago there was a student union at the university where I was studying. We had a space dedicated to us in one of the buildings near the campus area.
Some of the members wrote a program to retrieve subway departures and show them on a screen in our space.
The authors of said program made it simple but friendly. It would show all upcoming departures from the subway station, with the number of minutes until departures, and color coding.
A countdown with green color coding meant that you were likely to make it since there was a lot time left.
Orange color meant that you’d have to hurry up and go to make it.
Red meant that you’d really have to run, and that even then you might not make it.
Very handy system, especially for late nights when you had to pay attention so that you’d get on the last subway for the night that would take you home.
I loved that student union. Easily the best part of studying at the university for me was being a member of that student union. I have so much in my life to thank for the experiences I made from being a member in that student union :D