Train Graphic
Great Western Passengers' Forum Great Western Coffee Shop - [home] and [about]
Read about the forum [here].
Register and contribute [here] - it's free.
article index - [here]
 tomorrow - MRUG meeting
tomorrow - ACoRP board nominations close
18/10/2019 - TravelWatch SouthWest
18/10/2019 - GWR meet the team - Westbury
19/10/2019 - MRUG/CS "Thank you" BBQ
21/10/2019 - Ticket booking test - BRI
Random Image
Train Running @GWR Twitter Acronyms/Abbreviations Station Comparator Rail news GWR co. site Site Style 1 2 3 4 Chat on off
Next departures • Bristol Temple MeadsBath SpaChippenhamSwindonDidcot ParkwayReadingLondon PaddingtonMelksham
Exeter St DavidsTauntonWestburyTrowbridgeBristol ParkwayCardiff CentralOxfordCheltenham SpaBirmingham New Street
October 15, 2019, 03:07:14 am *
Welcome, Guest. Please login or register.

Login with username, password and session length
Forgotten your username or password? - get a reminder
Most liked recent subjects
[94] London Overground - proposed ticket office reduction of hours
[84] Restoration of original prototype HST to service
[56] Climate Change Emergency - Implications for UK Transport Strat...
[52] IETs into passenger service from 16 Oct 2017 and subsequent pe...
[47] Collapse of Thomas Cook
[44] On crossing borders by public transport - to and within the UK...
News: A forum for passengers ... with input from rail professionals welcomed too
 
   Home   Help Search Calendar Login Register  
Pages: 1 ... 30 31 [32] 33 34 ... 59
  Print  
Author Topic: Great Western Main Line electrification - ongoing discussion  (Read 103068 times)
martyjon
Transport Scholar
Hero Member
******
Posts: 1805


View Profile
« Reply #465 on: November 02, 2018, 05:35:30 pm »

Good picture in this evening's Bristol Post, showing the state of electrification at Hatchet Road (just after Bristol Parkway):

Image from Bristol Post
Incidentally, I can't help noticing that this is another bridge where the height warning is given in US Customary units only - is there a pattern emerging here? https://goo.gl/maps/uEs1mQrrHaC2


Open Top Rail Replacement Services now, might be a first. Luckily there were no passengers on board.
Logged
Bmblbzzz
Transport Scholar
Hero Member
******
Posts: 2255


View Profile
« Reply #466 on: November 02, 2018, 07:11:20 pm »

Full marks to the "huge steel barrier," which worked as intended.

Quote
The bus hit the bridge with such force that the roof of the bus was sheared clean off, and the bus continued on for a few more yards before coming to a stop.
A few more yards? It looks like about three bus lengths from the point where it first hit the bridge.
Logged

Day return to Infinity, please.
stuving
Transport Scholar
Hero Member
******
Posts: 4167


View Profile
« Reply #467 on: November 02, 2018, 08:35:42 pm »

Full marks to the "huge steel barrier," which worked as intended.

The full quote is "An initial inspection of any impact damage to the bridge revealed the bridge came through the experience unscathed - a huge steel barrier at the entrance to the bridge took the full force of the bus's roof, and protected the bridge as intended."

Well, they are still running trains over that "barrier" - it's the the northern, steel, bridge put there some time after the Severn Tunnel and the line from Wootton Bassett were built. That is 15'2" up, which is plenty to take a double-decker under - so it didn't hit it. It hit the brick arch, having failed to move out to the middle of the road, which is why the roof in the picture on Bristol Live lies under the steel bridge. Draw your own conclusions about the reporting!

Logged
BBM
Hero Member
*****
Posts: 527


View Profile
« Reply #468 on: November 02, 2018, 09:29:26 pm »

BBC News has a video of the actual incident involving the bus hitting the bridge:

https://www.bbc.co.uk/news/uk-england-bristol-46077532
Logged
SandTEngineer
Transport Scholar
Hero Member
******
Posts: 3007


Climbing a Pole Somewhere in the far Southwest


View Profile
« Reply #469 on: November 03, 2018, 11:39:42 am »

Full marks to the "huge steel barrier," which worked as intended.

The full quote is "An initial inspection of any impact damage to the bridge revealed the bridge came through the experience unscathed - a huge steel barrier at the entrance to the bridge took the full force of the bus's roof, and protected the bridge as intended."

Well, they are still running trains over that "barrier" - it's the the northern, steel, bridge put there some time after the Severn Tunnel and the line from Wootton Bassett were built. That is 15'2" up, which is plenty to take a double-decker under - so it didn't hit it. It hit the brick arch, having failed to move out to the middle of the road, which is why the roof in the picture on Bristol Live lies under the steel bridge. Draw your own conclusions about the reporting!

Information posted elsewhere suggests there isn't a bridge protection beam there and the bus hit the brick arch after clearing the parallel steel span.
« Last Edit: November 03, 2018, 12:17:54 pm by SandTEngineer » Logged

Out of this nettle, Danger, we pluck this flower, Safety.
[Henry IV, Part 1, Act 2, Scene 3]
Red Squirrel
Global Moderator
Hero Member
*****
Posts: 3186


There are some who call me... Tim


View Profile
« Reply #470 on: November 03, 2018, 12:22:05 pm »

Full marks to the "huge steel barrier," which worked as intended.

The full quote is "An initial inspection of any impact damage to the bridge revealed the bridge came through the experience unscathed - a huge steel barrier at the entrance to the bridge took the full force of the bus's roof, and protected the bridge as intended."

Well, they are still running trains over that "barrier" - it's the the northern, steel, bridge put there some time after the Severn Tunnel and the line from Wootton Bassett were built. That is 15'2" up, which is plenty to take a double-decker under - so it didn't hit it. It hit the brick arch, having failed to move out to the middle of the road, which is why the roof in the picture on Bristol Live lies under the steel bridge. Draw your own conclusions about the reporting!
Information posted elsewhere suggests there isn't a bridge protection beam there and the bus hit the brick arch after clearing the parallel steel arch.

As you suggest there clearly isn't a CPB - this is the view from where the bus entered:

https://goo.gl/maps/e1N696vDEnp

...and this is the view from the other side:

https://goo.gl/maps/QfoiS3VqA312

Edit: corrected Google Maps links

Logged
martyjon
Transport Scholar
Hero Member
******
Posts: 1805


View Profile
« Reply #471 on: November 03, 2018, 01:12:20 pm »

Full marks to the "huge steel barrier," which worked as intended.
The full quote is "An initial inspection of any impact damage to the bridge revealed the bridge came through the experience unscathed - a huge steel barrier at the entrance to the bridge took the full force of the bus's roof, and protected the bridge as intended."

Well, they are still running trains over that "barrier" - it's the the northern, steel, bridge put there some time after the Severn Tunnel and the line from Wootton Bassett were built. That is 15'2" up, which is plenty to take a double-decker under - so it didn't hit it. It hit the brick arch, having failed to move out to the middle of the road, which is why the roof in the picture on Bristol Live lies under the steel bridge. Draw your own conclusions about the reporting!
Information posted elsewhere suggests there isn't a bridge protection beam there and the bus hit the brick arch after clearing the parallel steel arch.
As you suggest there clearly isn't a CPB - this is the view from where the bus entered:
https://goo.gl/maps/e1N696vDEnp
...and this is the view from the other side:
https://goo.gl/maps/QfoiS3VqA312
Edit: corrected Google Maps links

.... and very apt that the second link should show a double decker turning right into the Bristol Parkway Estate.
Logged
ellendune
Transport Scholar
Hero Member
******
Posts: 3332


View Profile
« Reply #472 on: November 03, 2018, 01:48:15 pm »

When approached from the north side there are no white lines on the bridge to point out the need to be in the centre of the road.
Logged
stuving
Transport Scholar
Hero Member
******
Posts: 4167


View Profile
« Reply #473 on: November 03, 2018, 02:00:55 pm »

When approached from the north side there are no white lines on the bridge to point out the need to be in the centre of the road.

That's true - and I'm sure there should be. But look left from the initial Street View and there's a roadside sign, plus a dashed line on the road. However, given that the first bridge hides the second, I'd expect words and arrows on the road too (plus those width lines). Note that from the other side there is no line on the road, though there is the same roadside sign.
Logged
paul7755
Transport Scholar
Hero Member
******
Posts: 4644


View Profile
« Reply #474 on: November 03, 2018, 05:48:58 pm »

Good picture in this evening's Bristol Post, showing the state of electrification at Hatchet Road (just after Bristol Parkway):

Incidentally, I can't help noticing that this is another bridge where the height warning is given in US Customary units only - is there a pattern emerging here? https://goo.gl/maps/uEs1mQrrHaC2
Streetview shows that there are advance signs in both metric and imperialunits on the approach, and also instructions to use the centre of the road.

Paul
Logged
stuving
Transport Scholar
Hero Member
******
Posts: 4167


View Profile
« Reply #475 on: November 03, 2018, 06:03:54 pm »

The rules - Traffic Signs Manual: Chapter 4 - say this about composite bridges:
Quote
COMPOSITE BRIDGES
7.25 Some bridges originally built as arches have been adapted with the addition of girders or beams. Where the arch is the lowest part, the whole structure should be signed as an arch bridge. Black and yellow striped plates (to highlight the profile of the arch) should be suspended from the bridge beam, together with further plates on the arch itself.

The signage it specifies for an arch bridge of this width includes a single chord (as on the north side) plus the roadside signs at the bridge which look right. There should also be advance signs and "route avoiding" arrows on other signs; I din't know if they are present here.

How often do you see an arch-shaped dangly thing under a bridge? Not often! The manual has more to say about them (straight ones are also used):
Quote
7.27 Experience has shown that these suspended plates will themselves be struck from time to time and that rigidly-mounted aluminium substrates are not suitable. Rubber or other flexible material should be used for the backing, suspended by means of chains or hinges fixed securely to the bridge structure by a method agreed with the bridge owner. The plates should not be fixed rigidly by screws or bolts to the face of the bridge, as there is a greater risk than with flexibly-suspended plates of them being dislodged and falling onto vehicles on the road beneath. The use of rubber-backed plates will help to avoid annoyance to nearby residents from the noise of hanging metal plates striking the bridge structure in wind or vehicle slipstream. It is recommended that the yellow parts of the marking should be retroreflective; they may also be fluorescent (see para 7.6). When the signs are lit, the plates should also be lit whenever practicable. This is particularly helpful where a girder bridge is followed by a more restrictive arch bridge.

And finally, road markings, which are in TSM Chapter 5:
Quote
HIGH VEHICLE MARKINGS AT ARCH BRIDGES
22.5 All bridges with a headroom of less than 16'-6"should be clearly signed. (Arch bridge signing is dealt with in Chapter 4, paras 7.16 to 7.19). Road markings, together with appropriate warning signs,can be used in the case of arch bridges to guide higher vehicles to the centre of the road, where the clearance may be greater than at the outside edges.

22.6 The HIGH VEHS marking (diagram 1024.1) is prescribed for use at arch bridges. High vehicles should be guided through the highest part of the arch using this marking and the arrow to diagram 1014, together with edge of carriageway markings to diagram 1010. These should be aligned with the chord marking on the bridge (diagram 532.2) which indicates the available headroom in the central part of the road...

Note: the current chapter 5 is dated 2003, so its references to chapter 4 are out to date - that is now the 2013 edition.
Logged
stuving
Transport Scholar
Hero Member
******
Posts: 4167


View Profile
« Reply #476 on: November 03, 2018, 06:23:03 pm »

Good picture in this evening's Bristol Post, showing the state of electrification at Hatchet Road (just after Bristol Parkway):

Incidentally, I can't help noticing that this is another bridge where the height warning is given in US Customary units only - is there a pattern emerging here? https://goo.gl/maps/uEs1mQrrHaC2
Streetview shows that there are advance signs in both metric and imperialunits on the approach, and also instructions to use the centre of the road.

Paul

For arch bridges the meaning of "advance" is a bit puzzling, since they are doing two things. At the bridge, the main concern is getting vehicles into the right bit of the road. At the last turning, or in advance, the concern is to prevent overheight vehicles going that way and diverting them. So the inserts within advance direction signs are the same as other low bridges, while the markings and the "final warning sign" (use middle of road) are specific to arches. But then, for some reason, single triangular signs at the last turning (with no "route avoiding" message) or further away have a little arch in them. Since that last turn can be miles back (needing a distance label) or right up close (as in Hatchet Lane), they may or may not be "in advance". Anyway, what I meant was something at least half a mile away.
Logged
Red Squirrel
Global Moderator
Hero Member
*****
Posts: 3186


There are some who call me... Tim


View Profile
« Reply #477 on: November 03, 2018, 06:56:35 pm »

Good picture in this evening's Bristol Post, showing the state of electrification at Hatchet Road (just after Bristol Parkway):

Incidentally, I can't help noticing that this is another bridge where the height warning is given in US Customary units only - is there a pattern emerging here? https://goo.gl/maps/uEs1mQrrHaC2
Streetview shows that there are advance signs in both metric and imperialunits on the approach, and also instructions to use the centre of the road.

Paul

Yes, the advanced signs use both sets of units, but the warnings on the bridge itself are in USCS only. Overall, it could be clearer.
Logged
johnneyw
Transport Scholar
Hero Member
******
Posts: 1123


Still want to work on the railways when I grow up.


View Profile
« Reply #478 on: November 03, 2018, 08:32:04 pm »

Good picture in this evening's Bristol Post, showing the state of electrification at Hatchet Road (just after Bristol Parkway):

Incidentally, I can't help noticing that this is another bridge where the height warning is given in US Customary units only - is there a pattern emerging here? https://goo.gl/maps/uEs1mQrrHaC2
Streetview shows that there are advance signs in both metric and imperialunits on the approach, and also instructions to use the centre of the road.

Paul

Yes, the advanced signs use both sets of units, but the warnings on the bridge itself are in USCS only. Overall, it could be clearer.

Is it just me or did the footage remind anyone else of the double decker bus in Live and Let Die?
Logged

Railway rock n' roll rebel. I once bought a return ticket and didn't go back!
stuving
Transport Scholar
Hero Member
******
Posts: 4167


View Profile
« Reply #479 on: November 03, 2018, 08:54:03 pm »

There doesn't seem to be any simple way of finding out where signs are mandatory, but the form they should take if present is prescribed (the word used) in The Traffic Signs Regulations and General Directions 2016. The Traffic Signs Manual generally repeats this in something resembling comprehensible English (which the TSRGD 2016 are not), but are all older than 2016 so may no longer be correct.

In the case of units on bridge signage, I found a Sunday Times report that a 2014 DfT consultation proposed making dual units compulsory on new signs but let old ones stay. That's consistent with the 2013 TSM saying metric is optional, and the TSRGD 2016 only showing the signs with both - but I wouldn't put it any stronger than that. Distances (along the road) are of course still to be given in miles.
Logged
Do you have something you would like to add to this thread, or would you like to raise a new question at the Coffee Shop? Please [register] (it is free) if you have not done so before, or login (at the top of this page) if you already have an account - we would love to read what you have to say!

You can find out more about how this forum works [here] - that will link you to a copy of the forum agreement that you can read before you join, and tell you very much more about how we operate. We are an independent forum, provided and run by customers of Great Western Railway, for customers of Great Western Railway and we welcome railway professionals as members too, in either a personal or official capacity. Views expressed in posts are not necessarily the views of the operators of the forum.

As well as posting messages onto existing threads, and starting new subjects, members can communicate with each other through personal messages if they wish. And once members have made a certain number of posts, they will automatically be admitted to the "frequent posters club", where subjects not-for-public-domain are discussed; anything from the occasional rant to meetups we may be having ...

 
Pages: 1 ... 30 31 [32] 33 34 ... 59
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.2 | SMF © 2006-2007, Simple Machines LLC Valid XHTML 1.0! Valid CSS!
This forum is provided by a customer of Great Western Railway (formerly First Great Western), and the views expressed are those of the individual posters concerned. Visit www.gwr.com for the official Great Western Railway website. Please contact the administrators of this site if you feel that the content provided by one of our posters contravenes our posting rules (email link). Forum hosted by Well House Consultants

Jump to top of pageJump to Forum Home Page