Unlike some other posters, I realise that you are after advice, not admonishment...
A simple quick step that will calm your dogs down in a short space of time (you will see results the first time you do this);
When you arrive home, do NOT engage your dogs for at least 5 minutes. You will feel a bit at first. This means, not talking to them, looking at them or touching them. If you do this, it will show your dogs (through your ignoring their existence) that YOU are the Alpha dog in your pack. This will go some way to calming their behaviour when you leave the pack, as YOU are the Alpha, and it is you who decides who comes to and leaves the pack.
This strategy may not stop their barking in its tracks, so to speak, but will reduce their anxiety somewhat, because they are being treated like dogs do in a pack, and not like humans pets.
Dogs get separation anxiety, and they bark because they know (through your past behaviour) that when they bark, you will return. They only stop after half an hour because you have not returned, and they are bored of barking! By ignoring them for the magic 5, you will re-enforce that you are not going to come and go because they bark at you.
If you get any guests that come to your house to also ignore for the 5 minutes period, it will help also.
Give it a try, it may help, it might not, but at least I'm trying to give you some positive advice - based on my own experience.