Whilst in theory you're probably right - I think the risk to established heritage lines is very low as they are part of the area's tourist offerings, so it's a bit paranoid to claim that lines like Swanage are 'under threat' from the road builders.
Some of the smaller, more marginal heritage lines are likely to fall by the wayside - the 400 yards of track and a couple of decrepit Mk1s and some industrial diesel shunters, but then again there have been no shortage of other heritage schemes which have failed and most of those have failed due to being a poor offering with little appeal.
Not being paranoid, I leave that to you. A question was asked I smiple answered with examples. I lived in the nearby hamlet of Aurn and Ridge for many years. Dorset Council highways department has been ant-rail for many years. What grants that have come from DCC to the railway come through Purbeck Council who are nomore. Back in the late 60's and 70's The council highways department supported the closing of a number of lines in the county to allow road inprovments. This included the Swanage line as well, had the money been around after the line closed. The by-pass would have been built in the 70's. As it was there was only enough funds to buy the trackbeds at the time.
The other lines being the Bridport line, the trackbed through Bridport is now the bypass. The old S&D line from Broadstone to Blandford used for MOD traffic to Blandford Camp, Highways wanted the line closed to remove a number of S bend bridges along the route. And then there is Poole to West Moors along the old line of the corkscrew, again used by the MOD for traffic to West Moors Oil depot. Again highways wanted the line closed for road inprovements. The section of line between Poole and Broadstone is now the Broadstone Way, The bridge over the Leigh road was removed to allow the road to be widen. The last section of track bed from Canford bottom is now under the Ferndown bypass. The line had it remained open would be very useful today with all that new housing.
The Highways department has not had its way all the time.
Take a look at a map of Poole and Borunemouth, You will see two major roads, the Dorset Way (A3049)from the Bakers Arms to Alderney roundabout, the other being the Wessex Way (A338) from Ringwood to Westbourne. These two roads were ment to linkup. You can still see land corridor to this day, Bouremouth West Station was in the way so it was closed. Where the council come unstuck when BR built a depot on the trackbed. The Wessex Way was to have used the track bed as far as the old Junction towards London. The road would have crossed over the line passed through the northeast corner of the industrial estate on Dalling Road then along the land corridor across Tabot Heath which is now a SSI. to link up with the Dorset Way
Back at the start of the 1990's, Swanage was aready an established heritage line running between Harmans Cross and Swanage with the line being extended towards Norden, the railhead had aready had reached Corfe Castle. Things looked very rosely and things were runnng well. Yet the railway come within days of being wound-up in the High Court and put into Liquidation. The general manager at the time had been out of his depth, rather than admit that there were major problems instead buried his head in the sand. Bills went unpaided, Letters unopened and the debt mounted every higher. It was only when one of the creditors contacted the chairman, that things come to light on how bad things were. It was a number of years before the railway was back on a firm footing. That process was Operation Millstone, which it was. It took another four more years to complete tha last mile of track to Norden before the line could open between Harmans Cross and Norden.
As you can see even a established heritage line can be at risk. Which is why Swanage was one of the first line to release an appeal due to the virus lockdown. The line having been that close to being would up before, they have have no wish to get that close again.
Absolutely correct. There is no chance of a by-pass along that route now. Congested as Corfe Castle is there would be outrage if a new road were cut through the area, as any by-pass along the trackbed would only be yards from the village. Better to have a regular rail service and encourage beach traffic to use the park and ride at Norden, or set one up further away even at Wareham.
There is still a great deal of support for a by-pass for Corfe in the area. The cars are not the problem, it is the heavy goods vehicles that are the trouble, shaking the foundations of the buildings they pass. The trackbed is far further away than a few yards from the buiildings plus there is thick line of trees as well.