Blackwall Tunnel Closures
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From: JNugent on 25 Jan 2010 18:56 Tom Crispin wrote: > JNugent <JN(a)noparticularplacetogo.com> wrote: >> Tom Crispin wrote: >>> JNugent <JN(a)noparticularplacetogo.com> wrote: >>>> The older tunnel wasn't really built for traffic at 30mph. The bends are/were >>>> necessary because of the geology of the ground and because of the places >>>> where the terminations were needed. >>> No. The bends are there to prevent horses bolting for the light, and >>> because of the geography of the Greenwich Penninsular. >> That's an additional - if far-fetched - reason you are proffering. It does >> not militate against the two I gave (indeed, you support one of them - >> probably both of them). >>> It is ironic that riding a horse through the tunnel is prohibited. >> Not really. The "horse bolting the light" story is highly likely to be an >> urban myth (unless you can find an authoritative source for it), and there >> would be nothing to stop the horses "bolting for the light" on the not >> inconsiderable relatively stretches between the outer bends and the portals. > Horses bolting for the light may be an urban myth, ....but that didn't stop you proffering it as a serious answer. > but engineers > designing bends in tunnels in the hope of preventing horses bolting > for the light is not. In that case, there'll be a reliable contemporary reference for it somewhere. Complete with an explanation of why horses didn't bolt for the light in (much straighter and longer) canal tunnels with towpaths and why the navigators didn't find it necessary to cater for it by building curved canal tunnels.
From: JMS jmsmith2010 on 25 Jan 2010 18:57 On Mon, 25 Jan 2010 23:24:18 +0000, Tom Crispin <kije.remove(a)this.bit.freeuk.com.munge> wrote: >On Mon, 25 Jan 2010 23:06:11 +0000, JNugent ><JN(a)noparticularplacetogo.com> wrote: > >>Tom Crispin wrote: >> >>> JNugent <JN(a)noparticularplacetogo.com> wrote: >> >>>> The older tunnel wasn't really built for traffic at 30mph. The bends are/were >>>> necessary because of the geology of the ground and because of the places >>>> where the terminations were needed. >> >>> No. The bends are there to prevent horses bolting for the light, and >>> because of the geography of the Greenwich Penninsular. >> >>That's an additional - if far-fetched - reason you are proffering. It does >>not militate against the two I gave (indeed, you support one of them - >>probably both of them). >> >>> It is ironic that riding a horse through the tunnel is prohibited. >> >>Not really. The "horse bolting the light" story is highly likely to be an >>urban myth (unless you can find an authoritative source for it), and there >>would be nothing to stop the horses "bolting for the light" on the not >>inconsiderable relatively stretches between the outer bends and the portals. > >Horses bolting for the light may be an urban myth, but engineers >designing bends in tunnels in the hope of preventing horses bolting >for the light is not. I assume that you have a source for this - other than Wikipedia? As others have pointed out elsewhere - why was this technique not used in other tunnels from Roman times onwards. What about canal tunnels? No - I am sorry - just an Urban Myth.
From: JNugent on 25 Jan 2010 19:03 Tom Crispin wrote: > On Mon, 25 Jan 2010 23:22:19 +0000, JNugent > <JN(a)noparticularplacetogo.com> wrote: > >> Tom Crispin wrote: >>> On Mon, 25 Jan 2010 22:05:36 -0000, "Brimstone" >>> <brimstone(a)hotmail.com> wrote: >>> >>>> "Tom Crispin" <kije.remove(a)this.bit.freeuk.com.munge> wrote in message >>>> news:5lsrl5927cjfh5ig17mrhlr1l91sl3gsh8(a)4ax.com... >>>>> On Mon, 25 Jan 2010 19:06:52 -0000, "Brimstone" >>>>> <brimstone(a)hotmail.com> wrote: >>>>> >>>>>> "Tom Crispin" <kije.remove(a)this.bit.freeuk.com.munge> wrote in message >>>>>> news:9torl55uapgit7eo6umctf0e1i1dvmfdoo(a)4ax.com... >>>>>> >>>>>>> I would prefer to dismount and catch a lift than either cycle over >>>>>>> 2.5Km of ramp or be delayed everytime a yacht passes below. >>>>>> What about it it's (say) a frigate or a destroyer? >>>>> I'd still prefer to use a tunnel. But it's only once or twice a year >>>>> that naval vessels moor higher up the Thames than Greenwich, and that >>>>> would be tolerable. Yachts pass beyond Greenwich to St Katherine Dock >>>>> or beyond several times daily. >>>> Why do you object to people using the oldest highway of all? >>> I have no objection at all. My preference would be for a tunnel that >>> would not impede traffic on the Thames in any way or cyclists and >>> pedestrians wishing to cross the Thames. >> Tunnelling is *very* expensive. The only justifications for a road river >> crossing would be that: >> >> (a) a bridge is (completely) impractical because of the width of the river >> (eg, as at Liverpool) or >> >> (b) [impractical] because of the density the riverside built environment (and >> that impracticality would vary with the required clearance height) or >> >> (c) that a bridge would be so aesthetically unacceptable as to make the huge >> expense worthwhile. >> >> None of those would necessarily come into play with a Thames bridge in inner >> London. The most recent bridge was built without too much fuss. Even a lift >> or bascule bridge would be cheaper than a tunnel. >> >>> A bridge lower than 65m is >>> likely to impede both river traffic and cyclists and pedestrians, and >>> would certainly impede either river traffic or cyclists and >>> pedestrians. A 65m bridge with cycleable ramps is wholly impractical. >> Probably. >> But does the bridge *have* to be 65m high? > The Port of London Authority will not allow anything less ....unless it swings or lifts? No problem with that. It already happens with Tower Bridge (crazily). And there are other examples around the country. > Ships of > that height on the Thames are rare, but the QEII bridge already > prevents the Tall Ships Race ever again starting from or visiting the > Pool of London. Boo-hoo.
From: JNugent on 25 Jan 2010 19:03 Phil W Lee wrote: > Tom Crispin <kije.remove(a)this.bit.freeuk.com.munge> considered Mon, 25 > Jan 2010 18:59:59 +0000 the perfect time to write: > >> We have been through this before. A bridge would have to rise or be >> able to be raised to at least 65m to allow the tallest ships that fit >> under the Queen Elizabeth II Bridge. A 1:20 ramp which would allow >> wheelchair access suggests a ramp length of 1.3Km each end. This is >> wholly unrealistic. >> >> The proposed Thames Bridge has a deck height of 15m, and even then the >> spiral ramps need to be around 300m long. The two towers are 80m tall. >> Cyclists will be delayed everytime the deck has to rise to allow >> larger river traffic to pass. >> >> I would prefer to dismount and catch a lift than either cycle over >> 2.5Km of ramp or be delayed everytime a yacht passes below. > > How deep would a tunnel have to be? > I'd have thought a tunnel with ramps would be far preferable to a > bridge with ramps, and wouldn't have to be moved out of the way for > river traffic, or be impassable in high winds. Is Tower Bridge impassable in high winds?
From: JNugent on 25 Jan 2010 19:10
Phil W Lee wrote: > Tom Crispin <kije.remove(a)this.bit.freeuk.com.munge> considered Mon, 25 > Jan 2010 18:59:59 +0000 the perfect time to write: > >> We have been through this before. A bridge would have to rise or be >> able to be raised to at least 65m to allow the tallest ships that fit >> under the Queen Elizabeth II Bridge. A 1:20 ramp which would allow >> wheelchair access suggests a ramp length of 1.3Km each end. This is >> wholly unrealistic. >> >> The proposed Thames Bridge has a deck height of 15m, and even then the >> spiral ramps need to be around 300m long. The two towers are 80m tall. >> Cyclists will be delayed everytime the deck has to rise to allow >> larger river traffic to pass. >> >> I would prefer to dismount and catch a lift than either cycle over >> 2.5Km of ramp or be delayed everytime a yacht passes below. > > How deep would a tunnel have to be? At minimum, it would have to be deep enough to completely clear all mains services, foundations of buildings (which might be quite deep on the riverbank), the sewers and storm drains. And that's only on the approaches. There's also be the little matter of staying far enough under the Thames to minimise risk of the river breaking through. > I'd have thought a tunnel with ramps would be far preferable to a > bridge with ramps, and wouldn't have to be moved out of the way for > river traffic, or be impassable in high winds. The vertical distance between street level and the carriageway of a tunnel at it's lowest point would require very long ramps (including the approaches). |