The A38 roundabout now occupies the site of original Stroudwater Navigation Bristol Road lock and bridge.
Work is now under way to cut a new canal channel through the middle of the (large) A38 roundabout as illustrated in the photo above. In addition, two new road bridges will be required - on e at each end of the dotted line.
A new lock will be constructed to the east of the roundabout (photo top right) at a later date.
For more information on the scheme - see the Gloucestershire Highways site.
The photos of the works below were taken in early February, so things will have moved on somewhat since then.