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 ?

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.

Oh, and welcome to SABRE!!!!

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.

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

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

The Auchenkilns roundabout on the A80 (RIP!) used to have netted screens on approach to reduce traffic speed.

Obviously a technique favoured by HCC - the approach to M3 J5 on the A287 from the east is the same.

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

These fences can also be seen on the A3(M) at junction 3.

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

So would blindfolding them

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.

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.

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?'

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

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 !!!!!

Was the Countess Roundabout meant to be a GSJ? There is space for a flyover/underpass at the roundabout where the carriageways split.

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

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



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.