What is the number of the road to the right? Two of the three numbers are unbracketed.
This is the A5183 approaching the junction from the north - the sign on the A405 approach has a similar treatment.
Originally uploaded to Coppermine on Dec 06, 2008 by t1(M)
If I'm not allowed two entries, can we postpone the A303 one as this one is more topical
Originally uploaded to Coppermine on Apr 25, 2009 by t1(M)
Approaching Park Street roundabout
How Park Street Roundabout could have looked if an alternative route for the M25 was chosen in the 1970s. One of the options was for the motorway to closely follow the A405 and A6 between Park Street Roundabout and Bignells Corner. The M10 would have provided M1 to M25 east movements and there would have been a short section of D4M motorway immediately west of Park Street Roundabout where the M25 merges into the M10 to cater for the additional traffic on the weaving section. There would have been no east facing slips at the roundabout and traffic heading east would use the existing A405. There is however an exit slip westbound from the M25 to the A405. All road numbers shown are from the period. A5 is now A5183 and A405 east of A5 is now A414.
Basic grade separation of Park Street Roundabout as one of the proposals for completing the northwest section of the M25 in the 1970s. Some of the options maintained the M10-A405-A6 route for movements between the M1 and M25 east. In this case all the junctions would have been grade separated to provide a freeflow route throughout.
An online upgrade of the A405 and A6 between Chiswell Interchange and Park Street Roundabout was one of the proposals in the 1970s for completing the northwest corner of the M25. The road however would have been all-purpose although the report states that a motorway would be possible. It would have resulted in flyovers for the A405 and M10 which would have merged above the roundabout making it a three level junction. The route would then be on a new alignment between there and London Colney Roundabout with the existing A405 being used for eastbound traffic joining at the roundabout since there are no east facing slips to the new alignment from the roundabout.