The problem is the duty cycle, not screen real estate - if you show a relative time, it needs to update frequently to remain accurate.
If it's 5:27 right now and the BART comes at 5:38, I need to update once per minute if I'm showing a "+11m" for that relative time to remain accurate. Since the display takes more than 30s to refresh and isn't readable while it's refreshing, that means it's useless > 50% of the time I try to glance at it.
Whereas with my current setup, I only update it once one of the BART arrival times is no longer in the future. So, right now it's showing arrivals at 6:23, 6:29, and 6:44. Which means the display will update at 6:23, 6:29, and 6:44. There's a little extra optimization added to only show BARTs that are at least 5min in the future, since the BART is a 5min drive from the location where the display is. Depending on the BART schedule, all this works out to roughly ~8min update cycle on average, meaning that the display is only unreadable due to refreshing about 6% of the time, which I find to be very acceptable.
Clearly the solution is to have two displays refreshing on a 30 second alternating cycle! Maybe add a third black and white high frequency screen displaying an arrow pointing to the currently active screen. I jest:)
It actually really makes me want to build a Solari board for my local metro station.
If it's 5:27 right now and the BART comes at 5:38, I need to update once per minute if I'm showing a "+11m" for that relative time to remain accurate. Since the display takes more than 30s to refresh and isn't readable while it's refreshing, that means it's useless > 50% of the time I try to glance at it.
Whereas with my current setup, I only update it once one of the BART arrival times is no longer in the future. So, right now it's showing arrivals at 6:23, 6:29, and 6:44. Which means the display will update at 6:23, 6:29, and 6:44. There's a little extra optimization added to only show BARTs that are at least 5min in the future, since the BART is a 5min drive from the location where the display is. Depending on the BART schedule, all this works out to roughly ~8min update cycle on average, meaning that the display is only unreadable due to refreshing about 6% of the time, which I find to be very acceptable.