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giblets46 wrote: ↑Sun Mar 17, 2019 18:44
Any route realistically needs to go south of Oxford for the reasons mentioned previously, plus any other route will cause chaos with other routes north of Oxford (eg A40. The southern routes major issue will be politics!
A fully online upgrade of the A34 (including Botley) seems to have been excluded at an early stage, for obvious reasons. But the A34+A420 route to the west is still in the mix, and had the highest BCR (1.3) as well as lowest capital cost (£4.1bn). It's one of only two remaining options:
Oxford sub-option 1 (S1): This route diverges from the A34 at the A415 junction
at Abingdon. From there it travels offline avoiding Abingdon Airfield by passing on
the west, until the route joins the existing A420. The route runs along the A420
until it re-joins the A34 and turns to the north until it intersects junction 9 of the
M40. From this intersection the alignment diverges to the east where bypasses
Bicester between Graven Hill and Ambrosden, passing across the A41 and then
from the A41 to the east-west rail corridor.
Oxford sub-option 3 (S3): [after diverging from the A34 north of Abingdon just
after the A4103 junction] this route passes to the south of Oxford via a new road
but instead of turning north it continues east to junction 8A of the M40. From
this point the route utilises the M40 by turning north to a new junction,
approximately 11km away, before turning north to pass the A41 west of Bicester
and joining the east-west rail corridor.
So essentially the routing will be via either the A420 or M40.
Apropos of nothing maybe, but one of the things announced by the Chancellor in his Spring Statement was £200+M for roads in the Didcot area - dualling of the A4130 at the Milton Interchange towards Didcot then a new bridge over the railway, through the former Didcot A Power Station site and heading up to the A415. This is more about infrastructure for the continued growth of Didcot than anything else, but shows the potential activity on the southern end.
The A43+A420 route is pretty clever- making use of some good standard A420 dual carriageway there, and opening up land around the existing A34 for the creation of some lovely car dependent estates. The Oxford Times contains detail about these in an article from earlier in the month, but the sheer number of popups and adverts that loaded meant I couldn't get to the UR to copy and paste it.
ColinB wrote: ↑Mon Mar 18, 2019 11:01
Sub option 1 is said to be the cheaper option. But they say they costed a D2 route, so I suspect they ignored the need to widen the A34.
The SOBC says this:
The entire length of the Expressway has been coded as a 2 lane dual carriageway, with no at-grade junctions and any local access roads redirected.
Also:
The scheme costs used in the assessment are not based on any design considerations and can only be derived from the length of online upgrade and offline sections of the scheme...
It has been assumed that each new mile of a missing link section generates an additional four ‘lane miles’ to be maintained; each upgraded mile generates an additional two ‘lane miles’.
From this it seems very likely they've provided a rough estimate of the cost of adding two lanes to the entire route, including the A34 section.
Having driven the M1 to A1 section today, it's hard to see how it could be widened. A lot of overbridges are very tight, and especially the newer ones.
The comparison in how we "do roads" between these places and the Peterborough A1(M) is stark.
marconaf wrote: ↑Mon Mar 18, 2019 20:51
Having driven the M1 to A1 section today, it's hard to see how it could be widened. A lot of overbridges are very tight, and especially the newer ones.
The comparison in how we "do roads" between these places and the Peterborough A1(M) is stark.
Well the Peterborough A1(M) is hardly typical of UK motorways but even in comparison with older motorways such as the Darlington bypass you would have to conclude the A14 is closer to the Redhouse to Darrington section of the A1,
On one trip an Astra had lost it - cant understand how it was summer and the road was dry - and the back end had gone through the railings and was hanging over the edge, shades of the final scene in the Italian Job. We had to wait until the passengers were rescued and the car dragged into lane 1 before we were allowed past.
Instead of simply knocking them all down, can’t they make some effort of repurposing the existing ones?? E.g. make one existing carriageway a foot+cycleway, and the remaining one an eastbound carriageway, or similar??
It seems an absurd waste of money to replace structures with only 10% of their working life gone (unless they’ve managed to suffer some severe deterioration).
Aside from A428-A6, which is already three lanes, it's only A6-A600 that's currently around the 60k AADT mark according to sabre maps. This is only a mile and a half long, with two bridges. The rest is 45k or lower so has some space for traffic growth.
So I guess they could do A6-A600 to coincide with the opening of the MK-Abingdon section, then come back later for the rest. Not perfect but there may have to be a limit to mission creep for the 'missing link' to actually be a deliverable project. And it will mean the A421 bridges at least get 25 years of use before replacement.
I think you're right. By 2030 we could have an expressway from Cambridge perhaps all the way to Winchester. But it might be all D2 and hence overloaded over much of its length. In which case I hope the new parts will be designed for ease of widening, but I would not bank on it.
Berk wrote: ↑Mon Mar 18, 2019 22:51
It seems an absurd waste of money to replace structures with only 10% of their working life gone (unless they’ve managed to suffer some severe deterioration).
I'm sure cost benefit analysis is done with any sort of works where replacement structures are required - i.e. does it cost more to build an existing carriageway with new, smaller structure, or is it more cost effective to demolish and replace the existing one. There's examples of both approaches all over the road network - the M20 bypass at Maidstone and M2 Medway viaduct being two examples at opposite ends of the scale for keeping an existing structure. Similarly, widening work on the M1 involved putting a wider tube within some of the underpasses, suchas at Redbourn and backfilling around it to carry the widened road, and further north the A43 was dualled by pushing a new tube under the M1. However equally there's plenty of examples of strctural demolition and replacement - e.g. on the A1 in Yorkshire and on the new A14.
The widening of the A2 through Westfalia in Germany was very interesting to watch in the late 90s, early 00s - they took the original D2 with inermittent hard shoulders and constucted a new four lane carriageway alongside (for three lanes plus continuous hard shoulder). This was done to modern design standards, using cuttings and embankments to give a much flatter and slightly straighter alignment. All the traffic was then moved onto the new four lanes, and the original carriageway was then obliterated, and also flattened/straightend and fully re-built, resulting in a modern D3M with as little disruption as possible.
*Very* long term. The old line is extant between Bicester and Bletchley, though it needs clearance and repair work. However, there are obstructions to the old route around Sandy, and a guided telescope has taken over the track towards Cambridge - plus the Busway occupies the route from Trumpington into the city. So new routes will have to be found, and the process for those will be no easier than for new roads.
Anyway, we probably need both.
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Both are needed in the long term. The existing road is a mess. The section between the A1 and M1 is a busy D2 that degenerates into an S2 urban road takes you through Milton Keynes and through various towns and villages to the M40. At the Oxford end the road is hugely overcrowded and dangeous. Of course Labour will lose few votes in these areas so politically it is seen as an easy target. Note that the railway is going to be more of a freight route rather than for passengers. It will allow containers to get from Felixstowe across the country to the Thames Valley without going through London. There was never that much through traffic on the old Varsity line it was more two branch lines that happened to meet at Bletchley.
It's this sort of short sightedness that really frustrates me. I bet that the housing gets built anyway, even without the road. Traffic on the existing road will continue to get worse (if that's possible...), and noone will switch to cycling as there isn't any NMU infrastructure and the existing road is just far too dangerous to cycle or walk on:
