A new 1.5 mile spur was to be built onto the existing Inverclyde route, and the Glasgow Central-Paisley line would have been upgraded to triple track, with the additional benefit of increasing capacity on the Ayrshire and Inverclyde routes.
A new 1.5 mile spur was to be built onto the existing Inverclyde route. An element of the project that did go ahead was upgrading the Glasgow Central-Paisley line to triple track to increase capacity on the Ayrshire and Inverclyde routes.