M275 declassification

[Gav]

https://pure.port.ac.uk/ws/portalfiles/ ... _V_2.1.pdf

it looks like there may soon be another reclassification of motorway to A road

[Bryn666]

Looks more like a consultant writing up a "look what we could do" than a fixed plan.

If they think replacing the M27 junction with a roundabout will make access to their developments better and National England Agency for Highways accept that then it really is true that they have no interest in highways management whatsoever and are just there to line developer pockets.

[Gav]

Looks more like a consultant writing up a "look what we could do" than a fixed plan.

If they think replacing the M27 junction with a roundabout will make access to their developments better and National England Agency for Highways accept that then it really is true that they have no interest in highways management whatsoever and are just there to line developer pockets.

sneaky bit is that the motorway is a rare one in that its managed not by the highways but by the city.

[Steven]

Looks more like a consultant writing up a "look what we could do" than a fixed plan.

If they think replacing the M27 junction with a roundabout will make access to their developments better and National England Agency for Highways accept that then it really is true that they have no interest in highways management whatsoever and are just there to line developer pockets.

sneaky bit is that the motorway is a rare one in that its managed not by the highways but by the city.

It's not that rare. But I do notice that that small stretch of the M27 and the A27 to the east appears to be managed by Portsmouth City Council and not the National Highways Agency for England according to the NSG; but not according to NHAE's network map.

I also note that the "consultants" appear to have done their so-called dilligence via Wikipedia and hearsay; and the report contains untruths and misunderstandings about the legal requirements of motorways.

[c2R]

That's a particularly terrible scheme - part of the whole raison d'etre of the motorway is to service the port. Converting the road to all purpose and replacing a free flowing interchange with a bloody roundabout to serve car-dependent development is exactly what Portsmouth doesn't need!

Even their intermediate proposal of declassification wrong.

[Peter350]

While I’m in no way of approval of downgrading the M275 to all-purpose, I can see why the developers might consider this. Currently the western section of Tipner Lane is only accessible via the motorway and thus prohibited traffic has to use a special access road next to the park & ride. If the island is developed for housing, non-motorway traffic would increase and a better all-purpose route would have to be provided for these vehicles. I guess opening the special access road to all traffic would be a non-starter as it would lead to rat-running through Tipner village.

[ABB125]

What absolute rubbish! Full of grammar and a couple of spelling mistakes.
What's a "light traffic" route?

I do, however, agree that the existing bridge could be reused; barring any structural features which prevent it, it should be possible to sacrifice the hard shoulders and some of the central reservation to provide space for cyclist/pedestrian access, and if needed I doubt anyone would complain if a bit of lane narrowing was done.

[jervi]

Some of the proposals seems a little silly. Surly the best solution for Tipner Bridge is to build a purpose built pedestrian & cycle bridge, do they really think that people are going to choose to cycle if they have to do it next to 6 lanes of traffic?
I do see some reasoning behind making the M27/M275 junction smaller, as it means they could build more houses/development onto the reclaimed land and also put in an intermediate junction on the M275 between the M27 & J1. Reducing the M27/M275 junction would result in a roundabout interchange (as they proposed) as there wouldn't be room for a free flow, and that would effect the very purpose of the motorway being there (for the port).

The additional junctions proposed are not great either, just encouraging car dependency, although an access point is needed somewhere so perhaps tie in access onto the J12 Spur.

[JammyDodge]

A lot of the report is interesting. I think the development of a mass-transit route along the M275 and under the M27 is a good idea
I also agree with the idea of redeveloping the junction with the M27 to unlock land, but I don't agree with the roundabout, as proposed.
I think that compacting the existing large multiplex would be a better option to retain free-flow into the city from the M25, but at lower speeds. With a half-diamond north of the bridge and modification to the trumpet to provide a through route:

[Micro The Maniac]

Quoting from the report,...

Portsmouth City Council (PCC) published proposals in 2020 for development of the Tipner West site located to the west of the existing M275 corridor (fig.1 & 2). The proposal extends the city by 27ha. on land to be reclaimed from Portsmouth Harbour
...
The reclaimed land area incurs on an SSSI, RAMSAR and Special Protected Area, and will probably impact tidal flows in Portsmouth Harbour.

Good luck with that!

On Portsmouth’s west there is a correlation between areas of multiple deprivation and the low number of households having a car.

"We propose to resolve that, by removing car access from everyone, thus lowering the average."

[jnty]

Some of the proposals seems a little silly. Surly the best solution for Tipner Bridge is to build a purpose built pedestrian & cycle bridge, do they really think that people are going to choose to cycle if they have to do it next to 6 lanes of traffic?

A purpose built bridge would be nice, but provided that it's well-segregated with good links I don't see why being near 6 lanes of traffic would be a huge issue for the commuting and utility cyclists this would presumably be targeting. There are busy bridge routes like this elsewhere which work perfectly well, like the Forth Road Bridge prior to the opening of the Queensferry Crossing. Certainly more pleasant than being on most busy urban S2s.

[jackal]

This may be the craziest bit:

the ‘A’ road, can be
developed more intensely to
deliver a welcoming city gateway
with buildings fronting a well
proportioned new street/boulevard.
Both sides of the street become
visually connected (and can also be
physical connected), allows great
intensity and efficiency of land use,
accommodates varying relative
ground levels and allows for repair
and intensification of the urban
fabric on land that is currently
sterilised alongside the existing
route.

The proposal appears to be to insert property frontages along an 80k AADT strategic road, Kingston bypass style. It's like 80 years of highway design never happened. I guess that's what you get when you unleash an architect on your transport infrastructure.

[c2R]

Indeed - it's the entrance to a really busy international port and naval and civilian dockyards. To make the environs of the present motorway actually pleasant would require burying the motorway underground, like the Dublin Port Tunnel.

[Bryn666]

This may be the craziest bit:

the ‘A’ road, can be
developed more intensely to
deliver a welcoming city gateway
with buildings fronting a well
proportioned new street/boulevard.
Both sides of the street become
visually connected (and can also be
physical connected), allows great
intensity and efficiency of land use,
accommodates varying relative
ground levels and allows for repair
and intensification of the urban
fabric on land that is currently
sterilised alongside the existing
route.

The proposal appears to be to insert property frontages along an 80k AADT strategic road, Kingston bypass style. It's like 80 years of highway design never happened. I guess that's what you get when you unleash an architect on your transport infrastructure.

Architects are increasingly trying their hands at traffic engineering with predictable results:

https://goo.gl/maps/9x1MfZeTe2DLE5m88
https://goo.gl/maps/AjMU7ZFHgMpCUHS46

[Owain]

Replace a full-blown GSJ with a roundabout?

Now please do tell me that I'm not right when I say that continental countries do it better.

[SteveA30]

How many bits of motorways are not controlled by NHAE? This would appear to be the trojans horse that developers are using to get their mits on them. It should be nipped in the bud now. They are already inserting rbts all over the place where there should be GSJ's. Removing GSJ's from motorways is just the next step....for them, with council's capitulating as they do.

[SteveM]

Mind you, this from a planning application in 2005, so the idea of downgrading the M275 is nothing new

https://publicaccess.portsmouth.gov.uk/ ... 102303.pdf

[SteveM]

I would have thought that if access to Tipner by 'ordinary' traffic was needed, the most logical thing to do would be to declassify / change to A road the section of the M275 between Tipner and Rudmore, which already has a bus lane instead of a hard shoulder and is wholly Portsmouth CC responsibility. It would be little different in feel to how the M275 already ends, delivering traffic onto the Mile End Road dual carriageway.

[Fluid Dynamics]

Absolute madness, as someone who grew up
In the city and saw it’s road network develop, the architects understand nothing about the city.

I’m not one to usually quote Wikipedia but

Portsea Island has the third-largest population of all the islands in the British Isles after the mainlands of Great Britain and Ireland; it also has the highest population density of any British Isle, and Portsmouth has the highest population density of any city in the UK outside of London.

Most of Portsmouth is an island and only 3 roads give access onto and off the island for a population now of 200k plus.

I also thought the PCC only managed the part of the M275 south of Tipner Bridge so changing the M27/M275 junction would need Highway England consent. I would like to see the traffic modeling for the slip road queues to that roundabout. Makes that roundabout on the Witney bypass look sane.

[Peter350]

Is there anything stopping developers from building in between the slip roads of existing GSJs? Because if not, why couldn’t they just leave the junction alone and build their tin sheds in between the slip roads as illustrated below?

The railway triangle about a mile to the east manages to fit in an industrial estate with a bridge over the eastern side to access it, so this is proof that such an arrangement could work.

Orange - access roads
Brown - areas for residential development