I think an icon like "Vehicle on Hard Shoulder" would be a good one.

In most cases, existing hazards work in these situations. You'll often have a vehicle on the side of the road where they are working, for example. And for construction crews, the construction hazard is probably going to be valid. I do agree that there are instances where those may not work, but we have to consider what makes sense to add or not add. We don't want to end up with dozens of different hazard types, but we also don't want to be too limited either. I'm not really sure whether I think we need another hazard type for workers. I haven't really seen many instances where another hazard type wouldn't be correct and there is always the generic hazard that can include a description.

Keep in mind as well, since it is on your list, that "picking up trash" should never be marked as a hazard. Moving vehicles should not be marked because there is no way to keep track of where that vehicle is at any given time and with about 5 minutes before anyone else sees the hazard appear, that vehicle could be anywhere. The same is true for mowing if it's a mower that travels down the highway (local mowing that cover only a small area can be different).

As far as emergency vehicle icons, I'm assuming you mean for your vehicle display? If not, what do you mean? As far as for your vehicle, that's been requested many times. It's possible they'll add those, but nothing has been said one way or another about them, which is pretty normal.