Mapper89062 wrote: ↑Thu Jul 20, 2023 16:54
https://highwaysengland.citizenspace.co ... e%20V5.pdf
It was rejected because of its cost, disruption to road users during construction and poor value for money (some of the low BCR no doubt coming from the high cost but I suspect also partly because it doesn't fit with the service area and other development).
Edit: from reading the TAR, another disadvantage is that it makes access between the M42 and the NEC and motorcycle museum worse. This is another example of development being allowed to mess up a strategic junction with direct access - I note that the Belgium and Bratislava junctions have no such construction directly off them.
Actually there was no BCR for the whirlpool (option 3D) because it was rejected at an early stage. Costs were calculated but benefits were not. The appraisal was largely qualitative and came down to a critical mass of the designers feeling uncomfortable about a large freeflow junction, which for most of them would be a completely alien concept, having spent their working lives with roundabouts and signals. (See
TAR from p. 61.)
For instance, for traffic they rated the whirlpool the same ('best') as the South Junction (2A and 2K) options, which are basically similar to what's being built, even though it's obvious that a full freeflow junction will be vastly better for traffic than roundabouts.
For safety, they rated the interchange as worst due to 'safety issues from GD04 assessment regarding impact to road workers' - apparently the fact that it removes conflicts between millions of vehicles per year is irrelevant compared to a very occasional and speculative risk maintaining freeflow links (how does the rest of the world manage?). The
SAR explains that the preferred option has 'an increase in the number of conflict points associated with the introduction of additional roundabout junctions, which also gives rise to a predicted increase in accident numbers' (p. 46). It was actually projected to result in 133 additional casualties during the assessment period. No equivalent safety assessment was ever undertaken for the whirlpool because it wasn't allowed to get that far - but you can be sure it would remove conflict points rather than add to them. Nevertheless it was rated as least safe and the roundabout-based 2K as most safe.
Four stakeholders (Birmingham Airport, NEC, NMM, Jaguar LR) didn't like the whirlpool, mostly due to disruption during construction. This was treated as an important selection criterion - a hundreds of millions of pounds investment at a nationally important interchange guided by the whims of a motorcycle museum. Given the treatment of the other criteria, one also wonders what kind of advice HE were giving the stakeholders about the options - the airport and JLR at least would have greatly benefited from a freeflow junction.
Perhaps most tellingly, there was no economic appraisal of the whirlpool. The TAR (p. 69) outrageously conflates economic value with construction cost: 'significantly exceeds budget thus providing limited return in value for money'. How can you calculate value for money when you have a numerator but no denominator?
I could go on, but in short, no the whirlpool wasn't rejected due to a poor BCR, but because the poor decisions of the design group prevented it (or any other sensible design) from getting far enough to get a BCR.
