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Map of Current and Planned Railways in the Arabian Peninsula
(upload.wikimedia.org)
All lines are currently in service except the purple and yellow lines which are under construction. The UAE portion of the Gulf Railway begun freight service and will begin passenger service between Abu Dhabi and Dubai later this year.
The orange line is a dedicated High Speed Rail with a service speed of 300 km/h (190 mph). The remaining line are shared with freight and have a service speed of 200 km/h (120 mph).
The loss of the Hejaz Railway is still a great tragedy. There are planned railroads that will connect to Iraq, and it is possible to go to Jordan from Saudi Arabia by train, but nothing like what has been lost so far.