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jackal wrote: ↑Fri Feb 24, 2023 09:01
There's no official policy, just the confluence of several factors:
1. Stivichall I assume was for safety reasons as the SLT reduced to a painted line on the slip road with poor compliance.
2. In other cases (like I suspect A1nb to A46eb) they are removed due to poor merge arrangements.
3. They want to use the space for other, more congested movements (e.g., one SLT plus two lanes for other turns becomes four signalised lanes).
4. The designers think two signalised left turn lanes are better than one freeflow one (false for any realistic set of timings at a busy junction - see M40 J9 or M6 J10).
If I were to give one over-arching reason though it would be that many engineers see freeflow as too difficult to do right in the DMRB context and signals as the solution to everything. They'll be on another job by the time its built and worse than the status quo ante.
Sounds about right. But how much would a couple of splitter islands cost at Stivichall? It's not particularly tight or constrained after all
M40 J9 is just perverse, coming not long after they had spent god knows how much adding the freeflow left at J4
jackal wrote: ↑Thu Feb 23, 2023 17:50
The other side of the junction is even worse, with strategic traffic actually reduced to two lanes so they can have their precious development access.
Sorry but you need to explain that a bit more, there has only ever been two lanes around the roundabout.
On the northern bridge there were three lanes; there still are but one is dedicated to the development access now. Compare Google satellite (before) and streetview (after).
Yes you are correct there were 3 lanes on the northern bridge for a few years from about 2016 to 2021. But the inside line was marked for A45W BHAM which is the all-the way around u-turn option with neligible traffic so there were then only two usable lanes for going onto the A46/A45E - which is a good thing as there are only two lanes on the sliproad!
Now, for A46 north-bound traffic, there are two lanes all the way from prior to joining the roundabout, around it, and up the sliproads heading east - there is no "reduction" to two lanes anywhere. But what would help is more drivers staying the same lane all the way around - so many keep switching lanes. Grrrr.
Thanks for that. Seems to be the same proposal as before - a dumbbell to the north with 50mph mainline. Not perfect but does a decent job at a slightly tricky site.
The PEIR mentions the 10 option shortlist:
Option / Brief Description
1 One-way traffic system on Clifford Bridge Road (70mph)
2 Dedicated bypass southbound (free-flow link) with fly-over northbound
(50mph)
3 Signalised T-junction (50mph)
4 Left-in/Left-out (LILO) connection to B4082 (50mph)
5 Compact Grade-separated Junction (fully compact junction) (50mph)
6 Fully Grade-separated Junction (70mph)
7 Left-in/Left-out (LILO) connection to B4082 (tight radii) (50mph)
8 Realignment of A46 Mainline with Left-in/Left-out (LILO) connection to B4082
(70mph)
9 Removal of A46 connection to B4082 (50mph)
10 Removal of A46 connection to B4082, with realignment of A46 Mainline
(70mph)
Following on from the options identification stage, three options were initially
taken forward to the options selection stage, with seven options discounted for
the following reasons:
• Option 1 is highly unlikely to be considered favourably by local road users
and residents and provides no meaningful benefit to the A46.
• Option 2 has insufficient capacity on the southbound free flow link. The
Option also does not fit within the budget.
• Option 3 is not considered practical given the need to have five lanes for A46
traffic at the stop line and the likely safety disbenefits of this traffic merging
into two lanes exiting from the junction. It would also not meet the overall
scheme objectives of having free flowing traffic on the A46, would severely
penalise off-peak journey times and does not fit within the budget.
• Option 4 impacts the existing Western Power Distribution (WPD) electricity
assets which would require relocation. This relocation cost is substantial and
cannot be afforded within the available project budget.
• Option 5 technically complies with the RIS requirement for “grade separation”
; however, compact arrangement is not suitable for traffic flows on
A46 and alignments would encircle Hungerley Hall Farm. It is not affordable
within the project budget.
• Options 9 and 10 do not provide any connectivity with the B4082, plus would
likely result in significant negative stakeholder reaction due the combination
of the removal of the connection to the local network. National Highways want
to meet the RIS requirements as far as possible and Options 7 and 8 are
superior in this respect.
The four options that made it to option selection were 6 (full GSJ), 7 (LILO), 8 (LILO) and the new option 11, which was a 50mph full GSJ.
The LILOs were rejected as they would worsen the local road network, while "Option 6 was discounted within the option selection stage as the newly aligned B4082 would have led to a significant reduction in the River Sowe’s floodplain storage and would have resulted in regular flooding of the road and local area".
From the options considered I can see how the ended up with Option 11.
Over 400 pages of a preliminary environmental report ! On a single junction improvement. And we wonder why it takes us so long and costs us so much to build anything in this country.
It does the job at this location, and given there are major flooding concerns - which will get worse with climate change - it is a good compromise. I know some on here think it's perfectly OK to tarmac over everything as long as the precious metal boxes get more rights than people but in the real world, as you rightly point out, this is fine for what it does.
Bryn Terminally cynical, unimpressed, and nearly Middle Age already. She said life was like a motorway; dull, grey, and long.
It does the job at this location, and given there are major flooding concerns - which will get worse with climate change - it is a good compromise. I know some on here think it's perfectly OK to tarmac over everything as long as the precious metal boxes get more rights than people but in the real world, as you rightly point out, this is fine for what it does.
Not disagreeing with the chosen option, but does anyone believe metal boxes should have rights? Journeys in metal boxes have value because people take them to engage in economic and social activities that they find worthwhile. These benefits have to be balanced against the dis-benefits of course. But people who put more weight on the former aren’t necessarily stupid or wicked.
The higher-speed designs may well have ended up requiring a 50mph limit anyway, since it's going to be little more than a kilometre from the new north-facing slips to the M6 junction.
Just your average mapper, bringing you a map-focused take on today's world
The northbound exit slip as planned still takes traffic on a lengthy journey to get to the B4082. Why not move it further south where the two roads run next to each other or is there an issue with placing it opposite the lake.
How would you like your grade separations, Sir? Big and complex.
Mapper89062 wrote: ↑Wed Oct 25, 2023 14:51
The higher-speed designs may well have ended up requiring a 50mph limit anyway, since it's going to be little more than a kilometre from the new north-facing slips to the M6 junction.
Not seen anything about those, what are the plans?
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Truvelo wrote: ↑Wed Oct 25, 2023 17:48
The northbound exit slip as planned still takes traffic on a lengthy journey to get to the B4082. Why not move it further south where the two roads run next to each other or is there an issue with placing it opposite the lake.
It would introduce another junction which is bad for traffic flow, the extra distance is negligible in the context of the wider network.
Bryn Terminally cynical, unimpressed, and nearly Middle Age already. She said life was like a motorway; dull, grey, and long.
Mapper89062 wrote: ↑Wed Oct 25, 2023 14:51
The higher-speed designs may well have ended up requiring a 50mph limit anyway, since it's going to be little more than a kilometre from the new north-facing slips to the M6 junction.
Not seen anything about those, what are the plans?
I'm sure Mapper is just referring to the new north-facing slips of the junction we're discussing (Walsgrave), which will indeed be 1km from the M6 J2 complex.
It really does make a lot of sense and has come up on various discussions previously (including I think on here), but the reference at the end to "residential development" is somewhat concerning as much of the land between the A46 and the hospital is in Flood Zone 3.
It really does make a lot of sense and has come up on various discussions previously (including I think on here), but the reference at the end to "residential development" is somewhat concerning as much of the land between the A46 and the hospital is in Flood Zone 3.
That'll be what the roundabout on the eastern side is for. New car-dependent housing that breaches the bypass.
It really does make a lot of sense and has come up on various discussions previously (including I think on here), but the reference at the end to "residential development" is somewhat concerning as much of the land between the A46 and the hospital is in Flood Zone 3.
That'll be what the roundabout on the eastern side is for. New car-dependent housing that breaches the bypass.
That is Rugby-council controlled rather than Coventry. And whilst since the eastern bypass was construction back in the '90s(?) and the Coventry side of the bypass has been built on, the Rugby side has remained undeveloped and is indeed green belt.
