Road route to Bahrain.

You can do a search here for visa info.

For the route, head to Salwa, pass through the border. Follow signs for Hofuf. When you reach Hofuf outskirts there is a huge round-about where they are building a new bridge. GO LEFT. This is very important. If you go straight you will end up in the centre of Hofuf and get lost! Going left takes you out by Al Ahsa Airport. At the airport round-about turn right, then first left at the overpass, then next right at the major junction. From here follow signgs to Abqaiq (Sometimes written Baqaiq!), then signs for Dammam. Basically this is all one road with no turns! when you reach the outskirts of Dhahran/Al Khobar you will see an overpass above you with a sign for Bahrain. You will turn right and follow this road to the Causeway.

Note: There are no speed cameras all the way to the border, but occasionally the police will sit under a bridge with a radar trap, especially in Abqaiq!