I did the 15km ride in my city to reach the factory.
I can tell you that it is very stressful to ride a bike on a busy road with no bike lane, filled with trucks driving at 70kmh (because this road is the one that trucks must take as they are not allowed to cross through the city). Then imagine doing it at 7 in the morning in winter, when it is still night and some ice patch.
Even if you make it alive, then comes the issue of shower availability. That's what is blocking me from riding the 35km from my current job: I have no access to a shower at work.
My city has the most extensive bike lane network in France, except for the place where workers are working. If you work in the city center, you are fine and it is pleasant, but then you are part of the lucky workers enjoying the benefits of living in a city.
Well I have been cycling on the roads since I was 12 and I have cycled to work all my career but the last 2 years so I know what a busy road is. It is hard to talk about safety / how stressful riding a bike is because it is totally personal. I am used to traffic in a way I am not hyper anxious on the road while my gf is literally frightened in the traffic and it is not entirely corelated to the actual danger.
For a 35km bike ride (used to do that), you definitely want a shower. For a 10km mostly flat ride? Take it easy and you should be fine just with a short cleanup and possibly t-shirt swap in the bathroom.
I've been known to ride with studded tires in the winter, works really well. It is actually safer to ride a bicycle with studded tires than a car with winter non studded tires on black ice in winter. It means a bit of investment in a dedicated bike/wheelset though. Same for riding in the dark. Blinky 5€ lights won't do but reflective wearables and decent bright front and rear lights can do a lot to increase visibility and safety.
Marking a bike lane or better create a separate bike lane secures people riding bicycle and convince them to take their bike
I grew up a in a village and sometimes took my bike to the next village, not many people did that. 5 years ago they created a separate bike lane. Now, every time I go back to my village I see at least one bike riding it, when before it was non existent.
My city has the most extensive bike lane network in France, except for the place where workers are working. If you work in the city center, you are fine and it is pleasant, but then you are part of the lucky workers enjoying the benefits of living in a city.