Given how it was snuck out at 5:34pm on St. Patrick’s day it’s perhaps not entirely surprising that only one media outlet picked up on the production of four chunky documents on Hammersmith & Fulham’s website – Londonist did a slightly pro piece on the 18th but other than that most of the press stuck with their Boris based piece from the 3rd March which as we saw yesterday wasn’t based on the final documentation which was created over a week later.

If you’re thinking they’ve got something to hide, you’d be right.  Let’s look at the four documents:

  1. the Feasibility Study – this is obviously based on the draft study published on the 12th February that prompted my original blogging, but tarted up with some CGI and a lot of guff
  2. the Masterplanning report – what the architects want it to look like, and damn the engineering (apparently there’s GLA involvement in here somewhere)
  3. the Geotechnical Study - a weighty 114 pages of detailed engineering analysis from CH2M-Hill Halcrow, who did the original 1988 London roads plans and presumably dusted a lot of that off
  4. the Economic Impact Assessment – aka ‘the one I haven’t read yet’, but considering it’s from Hammersmith’s Business Improvement District I expect it to be 99% horseshit

First off, the feasibility study cans option 2, the long tunnel from Chiswick to North End Road, although it doesn’t explain why.  The geotechnical study had actually come up with six options, a no-junction and junction option of each of the original 3:

  • 1a – Direct on-route burial of the flyover
  • 1b  – Same as 1a, with a crossing tunnel taking Fulham Palace Road underground round Hammersmith and up Shepherd’s Bush Road
  • 2a – Chiswick to Earl’s Court bored tunnel with cut and cover portions at each end, crossing under the river through the north of Barnes and back under the river south of the current flyover
  • 2b – Same as 2a, with junctions west to the A316 and east to Fulham Palace Road
  • 3a – Chiswick to Earl’s Court bored tunnel with cut and cover portions at each end, crossing under the river through the north of Barnes and back under the river south of the current flyover
  • 3b – Same as 3a, with junctions west to the A316 and east to Fulham Palace Road

Of these only 1a and 3a are in the feasibility study.

1a

Option1a3a

Option3a

 

No reason is given for jettisoning the other four options, although the junctioned ones are excessively costly, the N-S tunnel is stated as not actually doing anything for traffic flow and option 2 is merely a form of option 3 with more disruption within Hammersmith.

Notably none of the options actually matches what LBHF’s survey claims the public actually backed.  A quick look at the punters’ choice shows the following choices for the west portal:

  • 4% support for starting out past M4 J2 in Brentford
  • 3% support for starting at M4 J2
  • 7% support for starting at Chiswick Roundabout
  • 39% support for starting at Hogarth Roundabout
  • 1% support for starting at Hammersmith Town Hall

While for the eastern portal the choices were:

  • The Ark (basically the current flyover end) – 6%
  • Baron’s Court – 7%
  • North End Road – 7%
  • Warwick Road – 22%
  • Hyde Park Corner – 1%

It’s fairly clear therefore that the public survey showed a strong preference for a tunnel from Hogarth Roundabout to Earl’s Court, undergrounding the road for the entire borough.  This explains the bizarre obsession with the long tunnel option 3a, which runs from Sutton Court Road to Earl’s Court.  Why start so far west of Hogarth Roundabout?  Well, as it turns out the architects with their CGI and whizziness weren’t much good at engineering, as the geotechnical survey points out:

The tunnel must have a minimum of one tunnel diameter cover when underneath the Thames; this requires a depth of 36m below the level of the river bed (approximately 6m below ground level (bgl)). Therefore the portal must be a minimum distance of 900m to comply with 4% maximum gradient.

So the portal has to be a long way west of the river crossing.  The alternative, presumably, would be a long detour round the river bank to the north, with a distinct lack of places to use in order to launch tunnel boring machines and pull the muck out of – it helps to have a big piece of empty land.  Halcrow have selected the playing fields of St. Paul’s School in Barnes, which should help the Olympic legacy and means you can probably use barges to cart most of it away, but which also means the tunnel needs to cross the Thames twice, which in turn pushes the portal well west into the middle of Chiswick.  So far, so silly.

Option 1a, on the other hand, is essentially from Hammersmith Town Hall to Baron’s Court, which has at most 1% support amongst the public, with a strong dislike being expressed for the Town Hall as a starting point.  Why start there, then?  Well, it turns out the architects with the CGI and yada yada…

…the length and position of the portals is governed predominantly by the required depth and gradient of the tunnel. The western Open Cut begins 340m from the start of the west Flyover ramp…

In short: due to the need to dive down to get under the London Underground while not tunnelling so far west that the economic case goes out of the window, they’ve unfortunately come up with a location for the western portal that neatly ruins the entire case for the project with the public, who seem to have a total antipathy to any surface trunk roads in the vicinity, and who can blame them?  Worse is to come – far from removing severance, there already is a crossing point at the Town Hall, a subway which is also cyclable, which would be removed and replaced by a 230m long gash with four lanes of traffic in it, forcing anyone from the Town Hall heading for Furnivall Gardens to detour round the eastern end of the trench.  There would also need to be a lane either side for the substantial traffic coming off the A4 and heading for Hammersmith.  My rather shaky art skills suggest that would look a bit like this:

WesternPortalSmall1aHmm.  Doesn’t look much like the artist’s impression, which has a distinct lack of great honking concrete trench full of noise and pollution across the front of the Town Hall:

Furnivall_Architect

Turning to the eastern end of Option 1a the geotechnical document says:

The eastern Open Cut is 360m from the start of the east Flyover ramp; this point on Talgarth Road also has 3 lanes in each direction allowing space for the portal and a lane in each direction for traffic. The portals will consist of an open cut section from the current road level and leading to a depth of the portal approximately 270m. The current roadway is limited in width and the open cut will take the majority of the roadway and is likely to cause disruption to traffic.

Let’s put some visuals around that, shall we?:

EasternPortalSmall1aYes, that’s right, this time the trench fans have put it neatly across Gliddon Road, which is currently a through route from Fulham to Hammersmith, but is now severed by your severance removing scheme.  Furthermore, that’s Baron’s Court tube station in the lower centre, which is now neatly cut off from Hammersmith Road (to the north) and Hammersmith, Ealing and West London College. When I last had to use that crossing in the evening rush hour it was rammed.  So, more severance here too.  Oh dear.  Naturally the council’s image seems to be a completely different scheme, showing the portal a good way west of where it really is, with unrealistically steep ramps and no road down from the gyratory to join the A4 eastbound, which is also at odds with the Masterplan:

Ark_Architect

So, that’s Option 1a for you.  In the next instalments of this thrilling saga of spivs versus engineers we’ll examine Option 3a in similar fashion and then go on to look at whether the finances stack up (they don’t, despite what Boris said).  We’ll also reveal what the real point of this exercise is, so stay tuned.

 

 
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