When the initial route for the GCC railway was drawn up in 2004, it did not include a rail link onto the island of Bahrain. Instead passengers were expected to get off trains in Saudi Arabia and continue their journey across the King Fahd Causeway by road.

The reason for not including a line to Bahrain was that building a causeway to the island just for trains would not be cost-effective.

But the planned development of the Qatar-Bahrain causeway has given planners new options for connecting Bahrain to the network. Trains could now run onto the island over the Saudi-Bahrain causeway from the west, stopping at Manama before carrying on eastwards across the Qatar-Bahrain causeway to Doha before heading back to Saudi Arabia.

The GCC ministers now have to decide whether to build the line onto Bahrain, a line running along Saudi Arabia’s Gulf coast, which will miss the island kingdom altogether, or both.

Other parts of the route are also open to debate. In the UAE, ministers have to decide whether to approve a new line running from Al-Ain to Sohar Port in Oman, or simply stick with the original proposal to build a line from Fujairah to Muscat.

The Omani government has also still to make a decision on what route the network will take as it heads further south to the Yemeni border – with a coastal or an inland route both viable.

But it is the Bahrain connection that is the most important decision. If the reality of the GCC is ever to match its vision of closer union, it is vital that the members’ transport infrastructure connects all six states, not just some.

For that reason alone, the rail network must extend to Bahrain.