Oil, gas, power and the emerging low-carbon industries that sit at the centre of Gulf public finance and industrial policy.
The latest disruption is a reminder that Saudi Arabia's ability to produce crude and its ability to move barrels safely to customers are separate pieces of the global oil-security equation.
New trains can lift nameplate output, but customer commitments and realised pricing determine what the expansion earns.
Export capacity leads the headlines; engineering, shipping and local supply determine how widely investment reaches the economy.