Watchet was chosen as the WSR line's terminus, as it had been since the Middle Ages an important regional port on the Bristol Channel.

The commercial aim of the WSR in choosing Watchet as its terminus was hence to provide a wider and cheaper distribution route for goods from the port.

From the planning stage, the harbour was to be served by a network of tracks, reached by way of a steep incline down from the goods shed.

The compact area available and the steep access inclines restricted the maximum shunting length to six railway wagons.

On the mainline access track from the northeast, there was a goods loop and sidings to allow easier shunting and composition of outbound freight trains from the harbour.

The harbour was also linked to the independent West Somerset Mineral Railway, which brought iron ore from mines in the Brendon Hills southwest of the town, with the mineral railway tracks running further inland, roughly parallel with the mainline as far as Washford.