We are about to enter another period of major roadworks at the junction of Heol Isaf and Llantrisant Road.
The following advice is based on information received from Plasdwr:
From w/c 2 March, Plasdwr's contractors (Alun Griffiths) will start the process that will lead to the removal of the current Heol Isaf roundabout and replacing it with a new, four-way signalised junction as part of the infrastructure improvements for Plasdŵr.
While this work is taking place, the two original lanes on Llantrisant Road (on the West side of the exisitng roundabout) will be closed and traffic will use the newly constructed lanes on the northern side of the carriageway, where a temporary mini roundabout will be created allowing traffic to travel as normal along Llantrisant Road.
Traffic travelling from Heol Isaf will be able to use the temporary roundabout to turn right onto Llantrisant Road, heading towards Llantrisant. To head left towards Cardiff, traffic from Heol Isaf will use the newly constructed slip road to bypass the roundabout altogether. There will be no left turn at the roundabout for traffic coming from Heol Isaf.
Other work will include resurfacing the bottom end of Heol Isaf, Llantrisant Road between the roundabout and the garage - and Lantrisant Road to the west of the roundabout. These sections will be done in turn - and each section will take about a week to resurface (so a total of three weeks). It is expected that this work will be undertaken before the contractors remove the existing roundabout.
The roundabout should be removed by the end of April. This will be followed by the installation of the new traffic light system, which will govern the flow of traffic through the new crossroads.
To ensure the safety of road users and contractors, traffic lights may be installed, at various locations, between 9.30 am and 3.30pm. We understand that we will not see any traffic lights in use 24/7 - and no traffic light will be installed until the new slip road is ready for use.
These arrangements are expected to be in place until the new junction is complete in summer 2020.
Updates will be posted on Plasdwr's twitter feed: @plasdwr.
These timescales are correct at the time of writing.
In the meantime, the closure for 11 weeks of Heol Pant y Gored (in Creigiau) will inconvenience residents of Pentyrch and Creigiau - but it will also add to traffic using Heol Isaf, which will be used as part of the network of diversionary routes during the closure. You can read more about Pant y Gored here.
The changes to the Heol Isaf / Llantrisant Road junction will be followed by changes to the Parc Radur / Llantrisant Road junction. Again, the roundabout will be replaced by traffic lights - and it will look like this:
There will be another new junction, at Ty Gwyn. We understand that the new traffic lights will be used to control the flow of traffic into Cardiff during peak hours. So that, once a set volume of traffic has entered Cardiff, over a set period of time, the traffic lights will stay at red to give time for the roads beyond them to clear. In other words, Llantrisant Road will be used as a holding-pen, to control the flow of traffic through Radyr, Danescourt, Llandaf, Fairwater and beyond.
At the same time, a large park and ride facility is to be built near Junction 33 of the M4, with the aim of encouraging commuters out of their cars and onto buses.