Key information about road safety changes at main Cynon Valley route

Important measures to promote and improve road safety will be introduced on the A4059 between Abercynon Roundabout and Cwmbach. This follows a review of the road traffic conditions along this route, which was undertaken by officers in response to an increase in high-severity collisions in recent years. 

It is estimated the changes which will improve road safety and only add on average 25 seconds to thejourney time in each direction, over the distance of Cwmbach to Abercynon – depending upon the time of day.

 

In December 2024, the Council announced the review had been undertaken and that officers were developing road safety proposals at key sections of the A4059 – the main road through the Cynon Valley. Public notices have since been published detailing proposals for change. The Traffic Regulation Order process has recently been completed.

 

The road safety review was informed by the latest road collision and casualty data along with road traffic speeds. There have been several severe and sadly fatal collisions over the past five years – a high proportion of which saw speed as a contributing factor.

 

Council-commissioned automatic traffic counters also recorded the speed of motorists within the National Speed Limit sections of the A4059 over a seven-day period last year. Motorists’ average speed was 48mph, which is below the posted speed limit. However, there were 15 instances of motorists travelling at 100mph or over, with one vehicle recorded travelling at more than 127mph.

 

Changes to be implemented on the A4059 in the weeks ahead

 

Generally, there will be a 10mph speed limit reduction compared with current levels. The A4059 from Abercynon to Mountain Ash will become 50mph (currently National Speed Limit), with a shorter 40mph section at the Quarter Mile junction (currently 50mph). Mountain Ash Comprehensive to Cwmbach will become a 50mph route (currently National Speed Limit), with the 30mph and 40mph sections through Mountain Ash being unchanged. These zones will be clearly signposted.

 

In addition, the Council will be resurfacing the carriageway and renewing the coloured surfacing at Quarter Mile Junction, in addition to the new 40mph speed limit being introduced. During the review, officers explored the possibility of constructing a roundabout at this location, but traffic modelling has indicated that this measure would cause severe traffic congestion at peak times due to uneven traffic flows.

 

Further planned improvements include additionalcoloured surfacing at more of the junctions along the A4059 route to raise awareness and improve safety, and the renewal of cats’ eyes from Abercynon Roundabout to the Ysbyty Cwm Cynon Roundabout.

 

To coincide with the speed limit changes, an average speed camera system will begin monitoring vehicle speeds along the route. It will be installed in two sections – Abercynon Roundabout to Mountain Ash (near Cross Valley Link junction), and Mountain Ash Comprehensive School to Cwmbach (near the petrol station). These are intended to tackle those motorists who break the speed limit considerably, and will be installed at a point in the future.

 

A spokesperson for Rhondda Cynon Taf Council said: “Residents are being reminded about these key, permanent changes on the A4059 between Abercynon Roundabout and Cwmbach – which are being introduced in the coming weeks to promote road safety. Motorists will notice new average speed camera equipment and signage being installed soon, and the new speed limits that are being introduced will be clearly visible and shown. 

 

“These measures are aimed at targeting the minority of motorists who choose to travel at dangerous speeds on this route, rather than most road users who won’t be affected by the changes. In fact, our recent speed monitoring exercise saw an average speed of 48mph along this route – which is below the 50mph speed limit being introduced. The current 50mph zone around Quarter Mile junction will reduce to 40mph, noting the challenging road layout for motorists turning right to enter the A4059.

 

“Based on previous monitoring, it is estimated that around 85% of drivers won’t see any impact to their current driving speeds. In addition, journeys on the A4059 are estimated to become only 25 seconds longer on average in each direction over the whole length from Cwmbach to Abercynon following the changes – while the road safety benefits will be significant.

 

“Thanks to road users for your cooperation as these important measures, supported by South Wales Police and GoSafe, are introduced. They are aimed at ensuring all motorists travel at a responsible speed, for the benefit of the thousands of people who use this arterial route regularly. Please take extra care while getting used to the new arrangements.”

 

A spokesperson for GoSafe, the Wales Road Casualty Reduction Partnership, added: “GoSafe’s primary objective is to make Welsh roads safer for everyone. At locations with high numbers of serious and fatal collisions, it is only right that we work in partnership with the local highway authority, police service, and other agencies, to achieve significant safety improvements. 

 

“We fully support the efforts of Rhondda Cynon Taf Council to make the road safer. We’re confident that these measures will deter people from driving at dangerous speeds and reduce the number of people killed or seriously injured.”