The work of a Plastic, Reconstructive and Hand Surgery on Shabbat

Kvod HaRav,
I am a religious Orthodox Jew living in Australia.
I am a Plastic, Reconstructive and Hand Surgery Registrar. This means that I am currently specialising in this field, and am in training to become a Plastic, Reconstructive and Hand Surgeon. This involves things like limb and digit amputations, time critical hand injuries where vascular supply may be compromised, necrotising fasciitis, and other emergencies.
Until recently I have been (a) a general surgery registrar, and (b) working at a hospital within walking distance of my home.
I have recently been posted to a hospital that is a 35-45 minute drive and well outside walking distance (though still in the same city).
On discussing the issues surrounding Shabbos with people from both here and London, I have hear that some hold that if you are on call, you may either drive or catch a taxi to work if you are called in. I have not had need to use this in the past and therefore am unsure of the Halacha in this instance.
I have asked a Rav here in Melbourne and he suggested I email your organisation.
My question is regarding driving/transport to (and from) the hospital when one is on call for emergencies.
Thanking you very much for your help,
D S