Deliberately reducing visibility

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.

Moderator: Site Management Team

User avatar
RayF
Member
Posts: 44
Joined: Thu Jul 28, 2005 18:52
Location: Derby

Deliberately reducing visibility

Post by RayF »

As part of the work going on at the A38/A50 junction near the Toyota works south of Derby :

http://www.highways.gov.uk/roads/projects/10421.aspx

tall wooden barriers are being erected on the righthand side of the slip roads onto the roundabout.

I assume that these are to prevent drivers approaching the roundabout from seeing traffic on the roundabout until they are at the end of the slip road and force them to slow down.

Is this a new idea or has it been used elsewhere ?
User avatar
Matthew
Member
Posts: 3395
Joined: Sun Apr 04, 2004 11:11
Location: West Midlands

Post by Matthew »

It's not a new idea, no. Not that I can quite remember when I've seen it, but I know of one on the A1 around Nottingham (is it at Five Lanes End?).

Having said that, I'm suprised this is progressing. Whilst it's a very "fast" roundabout, the visibility looks no better or no worse than any other that-scale junction.
Opinion is purely my own and all those other exceptions and excuses.
User avatar
Matthew
Member
Posts: 3395
Joined: Sun Apr 04, 2004 11:11
Location: West Midlands

Post by Matthew »

Oh, and welcome to SABRE!!!! :)
Opinion is purely my own and all those other exceptions and excuses.
User avatar
PeterA5145
Member
Posts: 25347
Joined: Sun Mar 24, 2002 00:19
Location: Stockport, Cheshire
Contact:

Post by PeterA5145 »

It's also been done on the A303 Countess Roundabout near Amesbury in Wiltshire.

Deliberately restricting visibility seems to me to be a misguided and potentially dangerous policy.
“The human race divides politically into those who want people to be controlled and those who have no such desire.” – Robert A. Heinlein
User avatar
Danno B10M
Member
Posts: 2821
Joined: Mon Nov 15, 2004 17:08
Location: Stafford, mostly

Post by Danno B10M »

PeterA5145 wrote:Deliberately restricting visibility seems to me to be a misguided and potentially dangerous policy.
I quite agree. It's probably down to some road safety bod on the council wanting to slow traffic down.

Some roundabouts in Dundee have tall flowery 'fences' seperating the lanes, so you have to approach the roundabout at <10mph.

The junction between the B5031 and B5030 outside of Rocester is now a roundabout, although not shown on the map. Grass banks have been constructed so if travelling along the 5031 and turning right onto the 5030, then vision is seriously reduced until you're at the junction. It's a pain in the neck. Truck drivers would have no problems though.
You're never late, with a Scania V8
User avatar
M4Simon
Elected Committee Member
Posts: 10121
Joined: Sun Mar 17, 2002 22:35
Location: WGC, Herts
Contact:

Post by M4Simon »

rsorionboy wrote:
PeterA5145 wrote:Deliberately restricting visibility seems to me to be a misguided and potentially dangerous policy.
I quite agree. It's probably down to some road safety bod on the council wanting to slow traffic down.

Some roundabouts in Dundee have tall flowery 'fences' seperating the lanes, so you have to approach the roundabout at <10mph.

The junction between the B5031 and B5030 outside of Rocester is now a roundabout, although not shown on the map. Grass banks have been constructed so if travelling along the 5031 and turning right onto the 5030, then vision is seriously reduced until you're at the junction. It's a pain in the neck. Truck drivers would have no problems though.
10 years ago, the Colney Heath longabout on the A414 was upgraded, which included improving visibility. As a result, vehicle speeds increased, but so did the accident rate. Various signs and marker posts were added to reduce the visibility again, with a corresponding reduction in accidents. Personally, I think this was a sensible thing to do.

Simon
Did you know there's more to SABRE than just the Forums?
Add your roads knowledge to the SABRE Wiki today!
Have you browsed SABRE Maps recently? Try getting involved!

Please contact me if you want to know more
User avatar
A303Chris
Elected Committee Member
Posts: 3587
Joined: Mon Sep 20, 2004 14:01
Location: Reading

Post by A303Chris »

It has also been done on at the A33 / A339 roundabout on the Basingstoke ring road by installing several 6 foot close boarded fences. In My opionion very dangerous and does not seem to enhance road safety
paully
Member
Posts: 1196
Joined: Wed Sep 07, 2005 11:48
Location: Perth

Post by paully »

The Auchenkilns roundabout on the A80 (RIP!) used to have netted screens on approach to reduce traffic speed.
Guy
Member
Posts: 68
Joined: Fri Aug 19, 2005 14:51
Location: Wiltshire

Post by Guy »

A303Chris wrote:It has also been done on at the A33 / A339 roundabout on the Basingstoke ring road by installing several 6 foot close boarded fences.
Obviously a technique favoured by HCC - the approach to M3 J5 on the A287 from the east is the same.
User avatar
highwaymana31
Member
Posts: 3783
Joined: Sat Jan 25, 2003 11:27
Location: Keeping clear of idiots

Post by highwaymana31 »

PeterA5145 wrote:It's also been done on the A303 Countess Roundabout near Amesbury in Wiltshire.

Deliberately restricting visibility seems to me to be a misguided and potentially dangerous policy.
And before the fencing was erected, they rationalised signing, they applied yellow bar markings across the c/way on the approach, they applied anti-skid surfacing, they then put yellow backing around the signs, and still the accidents occurred. Putting up the fencing forces the d/heads to approach at a safer speed
Mr Brown, 1984 was a warning, not an instruction manual

http://uk.youtube.com/watch?v=JCwW_1rswyo
User avatar
sotonsteve
Member
Posts: 6079
Joined: Mon Aug 08, 2005 21:01

Post by sotonsteve »

These fences can also be seen on the A3(M) at junction 3.
Jeni
Banned
Posts: 7313
Joined: Sun Nov 28, 2004 22:28

Post by Jeni »

Oddly, at M5 J5, fences have been errected just before the Southbound slip road merges into the Motorway, stopping you from seeing what is on the Motorway untill you get there!

While I can see the logic on roundabouts, but errecting them approaching a merge is dangerous? You can't see what's coming and so cant adjust your speed accordingly
User avatar
PeterA5145
Member
Posts: 25347
Joined: Sun Mar 24, 2002 00:19
Location: Stockport, Cheshire
Contact:

Post by PeterA5145 »

highwaymana31 wrote:Putting up the fencing forces the d/heads to approach at a safer speed
So would blindfolding them :P

Surely you know in your professional capacity that improving sightlines generally tends to reduce collisions at junctions. You wouldn't deliberately engineer a road with lots of blind turnings just to make people take more care, would you?

It is nonsense to asset that slower automatically means safer.
“The human race divides politically into those who want people to be controlled and those who have no such desire.” – Robert A. Heinlein
boing_uk
Account deactivated at user request
Posts: 5366
Joined: Wed Dec 04, 2002 16:01

Post by boing_uk »

its been used on a few roundabouts in mk, where there was an accident problem because although the visibility to the road on the rght was good, anything approaching from the opposite direction turning right was obscured. Reducing the visibility slowed approaching traffic down and resulted in an instant reduction in the accident rates.

Where used appropriately, reducing the visibility is a very good idea.
User avatar
explo
Member
Posts: 443
Joined: Thu Mar 30, 2006 21:59
Location: Bangor
Contact:

Post by explo »

I've seen this in several places and it is certainly effective if a little annoying at times. I'd use the example of a motorway offslip where long queues develop because of it.

On an amusing aside, I informed my dad one day that there were plans to improve an accident blackspot by reducing the sight lines at the junctions. He clearly misheard me, when he wondered out loud; 'How would reducing the white lines make any difference?'
User avatar
highwaymana31
Member
Posts: 3783
Joined: Sat Jan 25, 2003 11:27
Location: Keeping clear of idiots

Post by highwaymana31 »

PeterA5145 wrote:
highwaymana31 wrote:Putting up the fencing forces the d/heads to approach at a safer speed
So would blindfolding them :P

Surely you know in your professional capacity that improving sightlines generally tends to reduce collisions at junctions. You wouldn't deliberately engineer a road with lots of blind turnings just to make people take more care, would you?

It is nonsense to asset that slower automatically means safer.
The problem with the A303 Countess r/bout is there was plenty of forward/sideways visibility to the r/bout, this led to many RTI's due to people literally hitting the r/bout at an inappropriate speed. As I pointed out, the fencing was the last safety measure to try and reduce the RTI's at this particular location. I wouldn't propose it for many locations, but in this location, it has made a big difference.

At no point did I suggest that "slower automatically means safer", I said it was appropriate at this location.

To quote Chris "Where used appropriately, reducing the visibility is a very good idea." A303 Countess r/bout is one example of this
Mr Brown, 1984 was a warning, not an instruction manual

http://uk.youtube.com/watch?v=JCwW_1rswyo
User avatar
Haydn1971
Member
Posts: 12426
Joined: Sun Apr 10, 2005 14:16
Location: Sheffield
Contact:

Post by Haydn1971 »

PeterA5145 wrote:Deliberately restricting visibility seems to me to be a misguided and potentially dangerous policy.
I've used this technique on several roundabouts, it actually does work and reduces the amount of overshoot accidents... However, it's only really appropriate to do this sort of thing where there is actaully overshoot accidents !!!!!
Regards, Haydn

:: Visit My roads in Sheffield mini site
:: View my photostream on Flickr
Puffin
Member
Posts: 85
Joined: Sat Jul 01, 2006 19:53
Location: London

Post by Puffin »

PeterA5145 wrote:It's also been done on the A303 Countess Roundabout near Amesbury in Wiltshire.
Was the Countess Roundabout meant to be a GSJ? There is space for a flyover/underpass at the roundabout where the carriageways split.
beeeeeeeeeeeeeeeeeeeeeeeeeeeep!
User avatar
Ste_Nova
Member
Posts: 928
Joined: Fri Jun 30, 2006 13:47
Location: St. Asaph, A55
Contact:

Post by Ste_Nova »

Jenehfa wrote:Oddly, at M5 J5, fences have been errected just before the Southbound slip road merges into the Motorway, stopping you from seeing what is on the Motorway untill you get there!

While I can see the logic on roundabouts, but errecting them approaching a merge is dangerous? You can't see what's coming and so cant adjust your speed accordingly
it may work as it will make people have to drive fast in a hope they can just filter in.... like your suppost to, i allways try and join as fast as my car will go so i don't have to make anyone pull out
cb a1
Member
Posts: 5361
Joined: Wed Jun 30, 2004 07:30

Post by cb a1 »

The sketch below is an illustration of a relatively common event I witness on the Dundee Kingsway.

Image

Car A is waiting to turn right and see Car B is turning left. Lorries D and E are stationary and Car A can't see Car C approaching at speed. The Kingsway itself (running right to left in the picture) has a 50mph speed limit. Whilst there is a deflection for the approach to the roundabout, it can easily be negotiated at 30mph.

Car C has good visibility to the right and can see that nothing is coming.

Cars A and C both pull out on the roundabout. Car A starting from 0mph, Car C from 30mph. Car C has to brake very heavily to avoid hitting Car A.

One possible solution here would be to reduce the visibility on the approach for Car C so they slow down.
Education makes the wise slightly wiser, but it makes the fool vastly more dangerous. N. Taleb
We tend to demand impossible standards of proof from our opponents but accept any old rubbish to support our beliefs.
The human paradox that is common sense
The Backfire Effect
Post Reply