As a planet, let's choose which side of the road we will drive on and stick with it. 6 PM would be 1800 hours. This won't happen anymore. And let's scrap daylight savings time altogether. Farmers ignore it.
Cows ignore it.
So should we. Let's make that standard world-wide. Wailing sirens in this country alert you to an approaching police car or fire engine. A better idea would be to digitally sample a screaming female voice, then program it into all emergency vehicles around the globe. Nothing like the internationally understood screeching human to alert you to imminent danger.