The study of British and Irish roads - their construction, numbering, history, mapping, past and future official roads proposals and general roads musings.
There is a separate forum for Street Furniture (traffic lights, street lights, road signs etc).
Registered users get access to other forums including discussions about other forms of transport, driving, fantasy roads and wishlists, and roads quizzes.
Truvelo wrote: ↑Sat Nov 17, 2018 14:11
Anyway, the plans aren't as impressive as I had hoped. The whole thing is in an open cut with no tunnels whatsoever. What it does provide is a route following the existing line as closely as possible
If you look closely at your linked map you will see a small river runs parallel, to the north. This section has the same issue as at Henlys Corner, that tunnels or even deep cuttings are impractical because of the liability to flooding from the high water table in the locality.
I always thought a low viaduct route astride the river itself would be the most effective solution !
So that’s the reason these sections were never improved.
That's a very flimsy reason if it is the case. I suspect the reason to put the road below ground level is for aesthetic reasons more than anything else and deal with the water table later. Having it raised, either on an embankment or a Westway style viaduct, would turn the locals against it. The 1960's proposals however did had it on flyovers at the Bowes Road and Green Lanes junctions but environmental considerations were a lower priority back then. In a 1962 document I have it suggests work would commence in 1967/1968 at the earliest but it took over 40 years to deliver an at-grade scheme
How would you like your grade separations, Sir? Big and complex.
Truvelo wrote: ↑Sat Nov 17, 2018 21:29
That's a very flimsy reason if it is the case. I suspect the reason to put the road below ground level is for aesthetic reasons more than anything else and deal with the water table later. Having it raised, either on an embankment or a Westway style viaduct, would turn the locals against it. The 1960's proposals however did had it on flyovers at the Bowes Road and Green Lanes junctions but environmental considerations were a lower priority back then. In a 1962 document I have it suggests work would commence in 1967/1968 at the earliest but it took over 40 years to deliver an at-grade scheme
Not particularly flimsy if you live next to it and have to put up with higher flood risk from concrete culverts not being able to process the volumes of water storm events cause.
Bryn Terminally cynical, unimpressed, and nearly Middle Age already. She said life was like a motorway; dull, grey, and long.
These type of conversations make me think, what about the Dutch, who have managed to provide lots of cuttings and tunnels, particularly to keep shipping running on their rivers system, whilst often being at or below sea level. Would seem to suggest that there is an engineering solution to such issues. I expect cost is/was a factor.
Berk wrote: ↑Sun Nov 18, 2018 17:01
If it’s as difficult as that for culverts to process water, they wouldn’t cope with normal rainfall. That sounds to me like a design issue...
This was a well known issue along the route, in particular the A40 Hanger Lane underpass beneath the North Circular, which flooded periodically, sometimes right up to the roof, not only disrupting the traffic for some days but also writing off the roof-mounted M&E equipment more than once. I don't believe it has done so for some years now, but whatever pumping etc provision was originally provided was clearly inadequate. Hence the longstanding "Headlights On" signage at each end of the underpass, only now fading. All the regulars still do it, including a short while ago, amusingly, a 1930s Austin Seven following me with pathetic little yellowed bulbs.
It's true, that someone maybe needs to learn from the likes of Louisiana State Highways (USA's poorest state) in the USA, with their substantial network built in swampland.
Incidentally, mentioned above is that the original property purchase was by London Transport, but I think they were only public transport then, and the North Circular was an MOT trunk road scheme - although the original 1930s concrete bridge parapets had the Middlesex CC logo cast into them.
