The Fun at Junction 41 Ends (For Now)

The trial partial closure of Junction 41 of the M4 in Port Talbot has been lifted, and
a detailed analysis of the impact was recently released by the Welsh Government.
(Pic : South Wales Evening Post)

It's been about a year since I first wrote on the partial trial closure of Junction 41 of the M4 in Port Talbot (Junction 41 Fun). The trial involved closure of the westbound sliproad during peak times (07:00-09:00 and 16:00-18:00 every weekday).

Trunk roads, which includes motorways, are the responsibility of the Welsh Government. The South Wales Trunk Road Agency – working on behalf of Business & Economy Minister, Edwina Hart (Lab, Gower) - recently published a formal report into the trial closure (pdf) and executive summary (pdf), the former including a relatively detailed analysis of the closure's traffic, economic and environmental impact.

If you're really hardcore, the National Assembly's Public Accounts Committee recently published an report into the value for money of the trunk road network (pdf). Knock yourself out; it's too much even for me - but there were relevant recommendations in there on road maintenance and project management if that's what floats your boat.


What did the trial closure set out to do?

Existing problems at J41 were said to include :

• Frequent congestion in both directions near J41.
• The motorway between J38-42 is below acceptable design standards, and the junction itself has "an unconventional layout".
• The frequency of junctions in Port Talbot mean there's a lot of "weaving" - traffic accelerates, decelerates and changes lanes rapidly over a short length of motorway.
• There's poor visibility of traffic joining the M4 at J41 due to concrete barriers along the elevated section.

The report says the trial had three main objectives :

• Improve journey time reliability between J38-42.
• Reduce journey times over the same stretch of M4 during peak times (whilst factoring in the impact of average speed cameras).
• Reduce the accident rate over the same stretch.

It was believed that the trial closure would have a positive economic impact. The quoted figures at the time were a boost of up to £1million to the local economy and increased M4 capacity of up to 11% westbound and 2% eastbound. £600,000 was also made available to Neath Port Talbot Council to undertake works on surrounding roads which would be affected by the trial closure.

A recent FOI request (pdf) showed that hard shoulder running was considered as an alternative, but due to the awkward layout of the motorway it was deemed impractical. Using the hard shoulder as a "run in lane" from Junction 41 westbound to the next off-sliproad was said to be "feasible" if current road design standards were relaxed, but was ruled out due to the accident record.


The Report's Key Findings

The trial closure did improve westbound journey times on the M4 (as desired), and doesn't seem to have
directly impacted Port Talbot town centre. Despite this, there's no reason for Edwina Hart to claim victory.
(Pic : ITV Wales)

Traffic

• Traffic broadly stayed at the same levels, but was distributed over a longer length of motorway, with more traffic joining at Junction 40.
• Average westbound speeds increased from 32mph to 45mph during the morning closure and from 27mph to 43mph during the evening closure; though average speeds overall (in both directions) were kept to under 50mph since the introduction of average speed cameras.
• Journey time reliability "improved considerably" westbound during the closure, knocking up to 34 seconds off usual journey times between Junction 40 and 41. However, over the J38-42 stretch, journey times increased by 18 seconds in the mornings, similarly eastbound journeys – believed to be due to speed cameras.
• As much traffic was diverted onto the A48 through Baglan and Briton Ferry as the Peripheral Distributor Road, with resulting increases in non-M4 journey times of up to 1mins 50 seconds westbound. It's said work to discourage traffic from using the A48 during closures wasn't carried out by NPT Council despite the funding and planning being put in place.
• The average queue length more than doubled at A48 Sunnycroft Roundabout from 9 cars on average to 25 cars during the morning closure, and 10 cars to 24 cars in the evening. There were also major queue increases on Seaway Parade during the evening closure. However, queues on the PDR significantly decreased in the evening.

Environmental

• All of NPT's nitrogen dioxide (NO2) monitors reported increases, with one very close to exceeding the Welsh Government target of 40μg/m3 in a calendar year (and actually exceeded it during the closure period). The Trunk Road Agency claim that because the data only covers 5 months there's a greater margin of error.
• Despite the above, it's estimated the closure resulted in a reduction of 150 tonnes of carbon emissions from westbound M4 traffic.

Economic

• The annual economic impact of the closure was £179,815 per year (the equivalent of 14,559 vehicle hours). This is despite the cost of the closure reportedly being in the region of £800,000.
• Lengthier eastbound journey times (which weren't affected by a sliproad closure) have resulted in a negative economic impact of -£378,355 (30,634 vehicle hours).
• The number of car parking tickets issued at Port Talbot sites declined (with a spike in March 2015), but this was in line with long-term trends. In real terms this amounts to 14 fewer parking tickets issued each day than normal (based on the trend). There's no change to the time when parking tickets are bought either.
• During weekdays, footfall at the Aberafan Shopping Centre has fallen in line with long-term trends at a Welsh and UK level. Footfall at weekends has remained stable. Like car parking tickets, there was a spike in footfall during March 2015. There was no noticeable decline in footfall when the junction was closed, and declines aren't restricted to times when the junction was closed.

The report claims that the closure has met the first two of its objectives and hasn't "adversely affected the majority of key routes through Port Talbot". Data on accident rates are collected by the police and the report says there's usually a 6-month delay in publication, so for the time being it's impossible to tell if the third objective has been met.

What happens next?

If the report's results are to be believed, campaigners' concerns were largely unfounded
- but they might have won by accident.
(Pic : Port Talbot Magnet)

Edwina Hart has come under criticism for how this has been handled, but what I will say that she was right to trial this instead of deciding to close the junction permanently without an evidence base. I don't see why there couldn't have been more detailed computer models before pressing ahead with a real-life trial though.

The evidence suggests the closure hasn't had the negative impact on Port Talbot traders as campaigners claim, as any declines were in line with long-term high street trends.

However, this closure clearly caused serious problems on the A48 through Baglan, underlined by the report's own findings. The Trunk Road Agency say that's because NPT didn't bother to put in measures to deal with the traffic, but as it's (mainly) a residential road, those problems and concerns shouldn't be brushed aside so easily.

The Agency aren't responsible for the A48, but it was going to be the obvious choice for motorists diverted from Junction 41. The road isn't built to cope with those levels of traffic, so by making Junction 41 safer at M4 level, it's made the A48 comparatively less safe and more congested; anyone with half a brain could see that coming.

Considering the ambitions this trial set out with, it's a Pyrrhic victory for Edwina Hart. The closure "works", but the time savings, emissions savings and economic impact are much, much less than the Welsh Government would've anticipated - before taking into account the bad PR caused by the campaign and the Minister's own lack of forthrightness.

Based on the report's findings, the Welsh Government don't have a strong enough case to justify closing the junction permanently, and as she moves towards a post-Assembly life, I doubt the Minister has the fight left in her to trial closing both sliproads and leave a headache for her cabinet successor.

If the closure's lifted for good, campaigners will have ultimately lost the argument, but still won. Politics, eh? That doesn't mean Junction 41 is fine the way it is – it isn't. The only long-term solution is a remodelling of the existing junction to make it safer, which would cost millions and be even more disruptive. It's far from over.