Unfortunately, the term "shared" is such an inexact state of being and only through first deciphering how the driveway is actually owned can the mutual obligations for maintenance be precisely determined.
There are numerous slip and fall lawsuits resulting from snow and ice on business premises. This comment briefly discusses each of three legal standards that may apply, depending upon the jurisdiction.
So far this week, snow has closed the Federal Government for three full days. Each day the Federal Government is closed, it costs the taxpayers $100 million in lost productivity. So far that's a cool $300 million.