Portishead reopening - speculative / suggestions thread.

[HSTEd]

Massive cost to include a lifting/swinging mechanism for such a small amount of benefit (limited opening times).

If it only has to open for the tall ship festival you could always just hire a crane and forget the lifting mechanism.
Smaller pleasure craft could be served by a drop lock if necessary.

I've been nervous about derailing the thread (I almost didn't mention it at all), but the problem (as I see it) is an hourly train to Portishead is probably not very attractive, and I don't think half hourly is really enough to fully achieve the potential of the line through Clifton Down

EDIT: As for the journey time, its 18 minutes from Bristol Temple Meads to Sea Mills, it will take 7 minutes to get from Temple Meads to Parson Street before you even start down the new line to Portishead. That's something five miles from the line opposite Sea Mills, and given the low speed of the drag, it might end up a handful of minutes faster but not many.

 

[zwk500]

If it only has to open for the tall ship festival you could always just hire a crane and forget the lifting mechanism.
Smaller pleasure craft could be served by a drop lock if necessary.

Drop lock on the tidal Avon? It's a 12m tidal range. Having a crane lift out a section would require a possession to do, which might be feasible if you can always guarantee the appropriate tide at times no trains are running, but of course you can't.

I've been nervous about derailing the thread (I almost didn't mention it at all), but the problem (as I see it) is an hourly train to Portishead is probably not very attractive, and I don't think half hourly is really enough to fully achieve the potential of the line through Clifton Down

Agree, but 1pth is better than no railway and to go higher at Clifton down would required redoubling.
Ideally Portishead would be 2tph, Clifton Down 4tph (2tph to Severn Beach, 2tph round the Henbury Loop to Parkway, IMO). But we are where we are.

 

[John R]

If it only has to open for the tall ship festival you could always just hire a crane and forget the lifting mechanism.
Smaller pleasure craft could be served by a drop lock if necessary.

It would not just be tall ships, or even the Harbour Festival. The Matthew regularly traverses the gorge, and as noted a drop lock seems a challenge given the tidal range (and what would be the capital and ongoing maintenance cost if it).

As an aside, the magnificent dual carriageway Plimsoll Swinging Bridge at the Cumberland Basin is currently a big problem in terms of maintenance or renewal. Nowhere have I seen any suggestion that the problem is solved by closing off access to the docks for taller vessels, so any bridge further down would certainly have to maintain existing access to Bristol Harbour.

It’s a complete crayonista flight of fancy, which a quick visit to the location would quickly dispel.

 

[AndrewE]

As an aside, the magnificent dual carriageway Plimsoll Swinging Bridge at the Cumberland Basin is currently a big problem in terms of maintenance or renewal. Nowhere have I seen any suggestion that the problem is solved by closing off access to the docks for taller vessels, so any bridge further down would certainly have to maintain existing access to Bristol Harbour.

probably something to do with the almost inalienable rights of water-borne traffic... It seems to be even more difficult to extinguish navigation rights than to close a station! (I suspect that the right to navigate tidal waters is enshrined in absolutely watertight(!) international treaties.)

 

[simonw]

I started my interest in railways at sea mills station many decades,ago. Even as a primary school pupil I could see that a rail bridge across the Avon there wasn't going to happen.

 

[zwk500]

probably something to do with the almost inalienable rights of water-borne traffic... It seems to be even more difficult to extinguish navigation rights than to close a station! (I suspect that the right to navigate tidal waters is enshrined in absolutely watertight(!) international treaties.)

It's delegated (secondary legislation) to amend Harbour legislation: https://www.gov.uk/guidance/harbour-orders#harbour-orders-overview. Bristol City Council is, I think, the Harbour Authority for Bristol itself and the Avon (not sure if separate entities are responsible for Avonmouth and Portbury Docks).

It's also unclear if the current navigation clearances are legally protected or would simply be updated if a bridge lower than the current lowest was built. Anybody know of any precedents or have the rather niche legal knowledge? It's all academic anyway, but is interesting to consider as currently there is no crossing between the M5 and Plimsoll Bridges other than the weight-limited and narrow Suspension Bridge.

 

[simonw]

It's delegated (secondary legislation) to amend Harbour legislation: https://www.gov.uk/guidance/harbour-orders#harbour-orders-overview. Bristol City Council is, I think, the Harbour Authority for Bristol itself and the Avon (not sure if separate entities are responsible for Avonmouth and Portbury Docks).

It's also unclear if the current navigation clearances are legally protected or would simply be updated if a bridge lower than the current lowest was built. Anybody know of any precedents or have the rather niche legal knowledge? It's all academic anyway, but is interesting to consider as currently there is no crossing between the M5 and Plimsoll Bridges other than the weight-limited and narrow Suspension Bridge.

I think the height of the m5 viaduct shows that there are restrictions on heights across the river.

 

[zwk500]

I think the height of the m5 viaduct shows that there are restrictions on heights across the river.

The M5 viaduct was built in 1974, construction starting in 1969. When it was planned the docks in Bristol itself were still a working port, and so it would have needed to provide sufficient clearance for boats working to the docks. Although the Matthew is 22m tall, so anything much lower than the M5's clearance (30m above high water) would trap the Matthew in the Gorge unless it did something to it's masts.

 

[simonw]

The M5 viaduct was built in 1974, construction starting in 1969. When it was planned the docks in Bristol itself were still a working port, and so it would have needed to provide sufficient clearance for boats working to the docks. Although the Matthew is 22m tall, so anything much lower than the M5's clearance (30m above high water) would trap the Matthew in the Gorge unless it did something to it's masts.

The Bristol docks effectively closed well before then. I remember it well.

 

[AndrewE]

The M5 viaduct was built in 1974, construction starting in 1969. When it was planned the docks in Bristol itself were still a working port, and so it would have needed to provide sufficient clearance for boats working to the docks. Although the Matthew is 22m tall, so anything much lower than the M5's clearance (30m above high water) would trap the Matthew in the Gorge unless it did something to it's masts.

It's not just the Matthew, I suspect that there are still absolute rights on navigable (including all tidal) waters - but I guess nation states can extinguish them if they want to take the potential economic hit.
(although maybe they are not inalienable: The Tamar bridge is one example where the Admiralty was able to specify the air draught that had to be allowed, which in turn governed how high the bridge had to be.)

The Bristol docks effectively closed well before then. I remember it well.

I lived in Bristol in 1971 to 1976 and I remember boats being unloaded at the sand wharf in the city centre. https://www.flickr.com/photos/fray_bentos/181105368 says active in 1975 (and " The trade continued into the 90s")
and https://www.bristolcivicsociety.org.uk/aiovg_videos/sand-dredging/ isn't dated but shows film of the operation.
I accept that it was the last remaining bit of commercial use, I would have loved to have seen it when it was busier.

 

[simonw]

It's not just the Matthew, I suspect that there are still absolute rights on navigable (including all tidal) waters - but I guess nation states can extinguish them if they want to take the potential economic hit.
(although maybe they are not inalienable: The Tamar bridge is one example where the Admiralty was able to specify the air draught that had to be allowed, which in turn governed how high the bridge had to be.)

I lived in Bristol in 1971 to 1976 and I remember boats being unloaded at the sand wharf in the city centre. https://www.flickr.com/photos/fray_bentos/181105368 says active in 1975 (and " The trade continued into the 90s")
and https://www.bristolcivicsociety.org.uk/aiovg_videos/sand-dredging/ isn't dated but shows film of the operation.
I accept that it was the last remaining bit of commercial use, I would have loved to have seen it when it was busier.

As I said 'effectively'. Not absolutely. They aren't absolutely closed even now.

 

[JKF]

I’d have liked to have seen two trains per hour, one to Temple Meads and one to a new Harbourside station behind the M-Shed - one of the previous proposals was to serve a Wapping Wharf station here, which would serve the city centre a bit better. Unfortunately the metro bus route has killed that off, and the line along the river would also need some serious work - the coal trains that used to run along here had to proceed only at high tide due to the subsidence risk.

 

[Dr A.Johnston]

Hi All

A new series of videos on YouTube looking at Portishead railway - Hope this is of interest to this group.

 

[AlastairFraser]

I don't oppose the Portishead reopening, but what about a foot tunnel under the Avon Pill-Sea Mills as well, to improve connections across the Avon avoiding Bristol city centre?

 

[AndrewE]

I don't oppose the Portishead reopening, but what about a foot tunnel under the Avon Pill-Sea Mills as well, to improve connections across the Avon avoiding Bristol city centre?

a) lots of costs to maintain it and no revenue if people have to walk
b) not a lot of demand either... So an investment basket case!

What size is the coal conveyor-belt tunnel which I think goes/went from Portishead to Avonmouth? Could you re-purpose the conveyor belt for passengers, as was done in coal mines? (only joking!)

 

[paul1609]

The M5 viaduct was built in 1974, construction starting in 1969. When it was planned the docks in Bristol itself were still a working port, and so it would have needed to provide sufficient clearance for boats working to the docks. Although the Matthew is 22m tall, so anything much lower than the M5's clearance (30m above high water) would trap the Matthew in the Gorge unless it did something to it's masts.

The M5 viaduct is on the End to End Trail (Walkers Lands End to John o Groats). It appears to be the in place for suicides in the bristol Area. Theres all sorts of little shrines commemerating people who have taken their life there. Many of them made out of beer cans its all a bit sad really.

 

[AlastairFraser]

a) lots of costs to maintain it and no revenue if people have to walk
b) not a lot of demand either... So an investment basket case!

What size is the coal conveyor-belt tunnel which I think goes/went from Portishead to Avonmouth? Could you re-purpose the conveyor belt for passengers, as was done in coal mines? (only joking!)

It may not be a profitable endeavour, but Bristol in particular is a hotspot for support of parties friendly to improvement of "active travel" infrastructure. I would have thought a cycle/pedestrian tunnel could attract some funding for improving "active travel" infrastructure in the West of England Combined Authority area.

 

[John R]

So firstly, Sea Mills and Pill are in no way opposite each other, so exactly where do you want this foot tunnel?

I’ll assume it’s Pill to somewhere around Portway Park & Ride, as there is no population opposite Sea Mills, so I can’t see what possible purpose that would serve.

One minor challenge of a tunnel between Pill and Portway P&R might just be the presence of an existing cycleway and footpath crossing the Avon just a stone’s throw away. Now admittedly the M5 crossing is not that attractive for walkers, and even for cyclists is a bit of a climb, but then a tunnel will have to have to be around 15m deep, so hardly a level route for cyclists either.

I have no idea how much such a tunnel would cost, but I can imagine there are numerous better things to spend the money on. And bearing in mind that one portal of the tunnel would be in North Somerset, where active travel has an exceptionally bad reputation after the council has spend millions on misguided bus lanes and an atrocious revamp of Clevedon sea front which is universally despised, and going to be partially reversed at even more cost to council tax payers.

 

[zwk500]

It may not be a profitable endeavour, but Bristol in particular is a hotspot for support of parties friendly to improvement of "active travel" infrastructure. I would have thought a cycle/pedestrian tunnel could attract some funding for improving "active travel" infrastructure in the West of England Combined Authority area.

The costs of such a tunnel for comparatively few users when alternatives exist would be extortionate in relation to any proposal within the urban area of Bristol itself. I imagine it'd cost far less to provide a cycleway of a standard that'd make the dutch envious all the way along the gorge on both sides and a connection onto Cumberland Road.

 

[Snow1964]

Portishead station will be quite a distance from the high street and seafront, which isn’t going to make it very attractive for incoming visitors, so traffic will mostly be one-way in the peaks. The original station was right in the heart of the town, but since we aren’t allowed new level crossings it has to terminate 500 metres short.

Strictly there is the option of doing similar to some bits of London DLR, use the wide formation (there used to be sidings), and build short embankment, with bridges over the roads and put station in heart of town (even if 6m higher elevation) possibly on a small viaduct.

Of course what is possible in engineering terms, might not get funding, but a station stuck out on some bleak windswept outskirts is a rather poor substitute to attract trade.

 

[The exile]

Strictly there is the option of doing similar to some bits of London DLR, use the wide formation (there used to be sidings), and build short embankment, with bridges over the roads and put station in heart of town (even if 6m higher elevation) possibly on a small viaduct.

Of course what is possible in engineering terms, might not get funding, but a station stuck out on some bleak windswept outskirts is a rather poor substitute to attract trade.

I know it adds extra distance to walk, but 500m short of a station that was “in the heart of the town” is hardly putting it “stuck out on some bleak windswept outskirts”.

 

[lachlan]

Unless I'm missing something, a pedestrian tunnel wouldn't serve Portishead so while it would do wonders for connectivity in Pill, you'd still have the question of how to improve transport to Portishead.

I know it adds extra distance to walk, but 500m short of a station that was “in the heart of the town” is hardly putting it “stuck out on some bleak windswept outskirts”.

Indeed and the station site is surrounded by housing, allowing easy commuting into Bristol. In the other direction, it will be a short walk from Portishead station to Sainsbury'a, Premier Inn and industrial sites creating employment opportunities in the other direction.

 

[John R]

I know it adds extra distance to walk, but 500m short of a station that was “in the heart of the town” is hardly putting it “stuck out on some bleak windswept outskirts”.

Quite, and it is still an easy walk for a large chunk of Portishead’s population, including all the new Marina development. Which is what is important, as outbound commuter traffic is the key driver of the project.

 

[Snow1964]

I know it adds extra distance to walk, but 500m short of a station that was “in the heart of the town” is hardly putting it “stuck out on some bleak windswept outskirts”.

For those who don't live in the South West, this is a street view of the area, where line formally crossed. Perhaps I was harsh with bleak, but not exactly inviting

Street View · Google Maps

Explore a place in a more immersive way in Google Maps.

www.google.co.uk

 

[John R]

For those who don't live in the South West, this is a street view of the area, where line formally crossed. Perhaps I was harsh with bleak, but not exactly inviting

Street View · Google Maps

Explore a place in a more immersive way in Google Maps.

www.google.co.uk

Have you been there? Do you understand its proximity to the housing nearby? And part of the reason it looks like that is that no development has been allowed because of the rail line and the anticipated link. It’s not typical of the area around it.

 

[AndrewE]

It may not be a profitable endeavour, but Bristol in particular is a hotspot for support of parties friendly to improvement of "active travel" infrastructure. I would have thought a cycle/pedestrian tunnel could attract some funding for improving "active travel" infrastructure in the West of England Combined Authority area.

While I am all for active travel, there must be far more "profitable" ways to spend the transport budget in the area.
One thing which hasn't been mentioned is the tidal range there... If the railway already gets closed because of flooding at Sea Mills, how high will the tunnel access shafts have to be to keep it safe?

 

[DynamicSpirit]

Have you been there? Do you understand its proximity to the housing nearby? And part of the reason it looks like that is that no development has been allowed because of the rail line and the anticipated link. It’s not typical of the area around it.

Correct me if I'm wrong, as I'm just going from Google maps, but it looks to me like you could extend the rail line as far as the Waitrose/B&M car park without needing to demolish anything significant. Then if you can come to an agreement with the retail park to reallocate some of the parking bays as long-stay ones, you have a station very close to the town centre and with ready-made park-and-ride parking too. Could that be workable?

 

[lachlan]

Correct me if I'm wrong, as I'm just going from Google maps, but it looks to me like you could extend the rail line as far as the Waitrose/B&M car park without needing to demolish anything significant. Then if you can come to an agreement with the retail park to reallocate some of the parking bays as long-stay ones, you have a station very close to the town centre and with ready-made park-and-ride parking too. Could that be workable?

I believe the issue comes down to not wanting to close Quays Avenue or build a level crossing and a bridge not being feasible.

 

[John R]

Correct me if I'm wrong, as I'm just going from Google maps, but it looks to me like you could extend the rail line as far as the Waitrose/B&M car park without needing to demolish anything significant. Then if you can come to an agreement with the retail park to reallocate some of the parking bays as long-stay ones, you have a station very close to the town centre and with ready-made park-and-ride parking too. Could that be workable?

Unfortunately not, as the ORR will not permit a level crossing at Quays Avenue, a stance which was confirmed early on in the project design stage. Which seems ludicrous, as trains could be cautioned to cross at 10mph given how close it would be to the terminus, so with a fully barriered crossing, I think the risk could be mitigated. But rules are rules I'm afraid, and far be it for us to question the ORR's approach.

 

[zwk500]

Strictly there is the option of doing similar to some bits of London DLR, use the wide formation (there used to be sidings), and build short embankment, with bridges over the roads and put station in heart of town (even if 6m higher elevation) possibly on a small viaduct.

Of course what is possible in engineering terms, might not get funding, but a station stuck out on some bleak windswept outskirts is a rather poor substitute to attract trade.

Putting the railway on a 6m high deck clearance for 500m will blow an enormous hole in the costs, which are already worryingly high. The station location, while not ideal, is hardly in 'bleak windswept outskirts' when it's opposite the health centre and adjacent to a housing estate.