Bontnewydd traffic problems survey is launched

[J--M--B]

BBC News

Page last updated at 12:56 GMT, Monday, 1 March 2010

Bontnewydd traffic problems survey is launched

Public consultations have begun on plans to ease traffic congestion at Bontnewydd near Caernarfon in Gwynedd.

The Welsh Assembly Government is asking local residents to comment on one of four possible bypass routes to help cut down on queues in the village.

The study will last 12 weeks and include public exhibitions at Bontnewydd and Caernarfon.

Projected costs for the new roads range from £40m to £86m depending on the route chosen.

An online document on the changes notes the Assembly Government has already looked at a "package of transport measures". ............

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Online document

Astudiaeth A487 Caernarfon i’r Bontnewydd
Ymgynghoriad Cyhoeddus 1 Mawrth hyd 24 Mai 2010

A487 Caernarfon to Bontnewydd Study
Public Consultation 1 March to 24 May 2010

[nowster]

Most interesting. I'd favour the Purple (most expensive) option, of course, as it's the better for gradients.

I might even attend the exhibition on one of the days. I might even find out why the Bontnewydd-Caeathro road is so well specified for a C road.

[Truvelo]

If the bypass gets built I wonder what it would mean for the GSJ in the middle of Caernarfon.

[gazzaman28]

The brown route makes the most sense as the current "unofficial by-pass" is quite a good alignment through Caethro, only really needing to be sorted out between the A4086 and the start of the Port Dinorwic by-pass roundabout. That should be the cheapest option but certainly not a bad one by any means. The only worry is that it will attract development alongside major junctions, always a problem with any new by-pass and IMO local authorities never do enough to prevent it.

[RichardA35]

Nice to see the WELTAG appraisal in use - decide you need a road then assess the different options. The integrated options are now secondary and should (so I'm told) ensure the issues that snookered the A494 at Ewloe are a thing of the past.

[worcsfan]

For those who don't know, the Bontnewydd congestion- considering it is only from Caernarfon and not a major conurbation- is something to behold. I was caught up in congestion once from Llanwnda to the Caernarfon gyratory- never to be forgotten and so out of place up there.

The 'relief road' from Bontnewydd to near Llanrug is another revelation if you are new to the area- a virtual bypass for Caethro on the west-east axis as opposed to the more obvious north-south axis. Love to know why it was built: I seem to remember that until the 90s, there was a Heath Robinson attempt to get traffic to Bangor via Llanrug that was later withdrawn- signposting removed as the road was oh so unsuitable at that point.

[J--M--B]

BBC News

Page last updated at 15:57 GMT, Tuesday, 9 March 2010

Bontnewydd bypass plans in public exhibitions

Plans showing four possible routes for a bypass at Bontnewydd in Gwynedd have gone on public display.

But already there are differences of opinion with a dispute about the route between Bontnewydd and the coast.

A local councillor said the bypass should go the other side of the village and make use of existing roads...........

[nowster]

A local councillor said the bypass should go the other side of the village and make use of existing roads...........

The land to the east of Bontnewydd has less easy gradients. It would also require realigning the existing A487 near Dolydd. The brown route does make use of the existing Caeathro road.

I'm hoping to visit the exhibition this afternoon on my way back to Manchester.

[nowster]

The land to the east of Bontnewydd has less easy gradients. It would also require realigning the existing A487 near Dolydd. The brown route does make use of the existing Caeathro road.

I'm hoping to visit the exhibition this afternoon on my way back to Manchester.

Actually, the land to the east of Bontnewydd has an SSSI, and has more buildings on it.

The most interesting thing is that the Purple route has a free-flow directional GSJ above Y Felinheli. I'll give a more detailed write-up later.

[owen b]

My experience, like others, is that Bontnewydd definitely needs a bypass. It nearly always seems to be slow going and congested whenever I go that way. I really wonder whether Caernarfon needs a full bypass though. It already has what I've always found to be quite an effective throughpass, and I wonder how much through traffic from Bontnewydd to Y Felinheli there actually is? The existing road is very narrow and hemmed in on the north east side of Caernarfon though.

[worcsfan]

The GSJ in Caernarfon is still superb- but you need some relief from St.Helen's Road to the Newborough Street gyratory and then on North Road from the Christ Church roundabout north...the old old story of a great futureproofed road that just moves the bottleneck along.

Even with the proposals on the table, I can see future bottlenecks at Llanwnda [from the south], Caethro [from the east] and Y Felinheli/Faenol[from the north].

It's a long way from a clear drive from the Expressway to Abersoch

[jackal]

My experience, like others, is that Bontnewydd definitely needs a bypass. It nearly always seems to be slow going and congested whenever I go that way. I really wonder whether Caernarfon needs a full bypass though. It already has what I've always found to be quite an effective throughpass, and I wonder how much through traffic from Bontnewydd to Y Felinheli there actually is? The existing road is very narrow and hemmed in on the north east side of Caernarfon though.

The difference in price between the Pink option (Bontnewydd bypass only) and Brown option (cheapest of the Bontnewydd and Caernarfon bypass options) is only £20m, or £40m versus £60m. So the traffic issues in Caernarfon would have to be pretty mild for the full bypass to be unjustified. Presumably that is not the case since the BCR of Pink is 3.36 and that of Brown is 4.62.

A niggle: The WAG report seems to think that S2+1 isn't single carriageway:

As a single carriageway it [the Brown Option] provides less overtaking opportunities than the other three bypass options.

The 2+1 carriageway standard provides safe overtaking opportunities between Llanwnda and Bontnewydd. On the single carriageway sections there are few designated overtaking opportunities.

[nowster]

They say in the document that it's S2+1, but the traffic engineers at the exhibition said that instead of a double white line, there would be a wide hatched area separating the two traffic streams. Whether that comes with a no overtaking restriction is to be seen. The sightlines on the demo video looked particularly good.

I've left my notes in the car. I'll bring the scheme leaflet to the AGM. I've even requested a PDF of the plans to be emailed to me. They'll probably not process that request until next week at the earliest. (They were uncertain about me taking photos, and offered that as an alternative.)

[owen b]

the traffic issues in Caernarfon would have to be pretty mild for the full bypass to be unjustified. Presumably that is not the case since the BCR of Pink is 3.36 and that of Brown is 4.62.

I would have thought (based on that leaflet and my limited personal experience) that if you're going to bypass Caernarfon the brown route would be more than adequate. The most expensive route seems extravagant and introduces unnecessary redundancy into the western end of the Port Dinorwic bypass for not a lot of benefit.

I'm rather surprised that Bontnewydd and Caernarfon are being presented together. While the traffic issues are clearly related, I would have thought that it would make sense to get Bontnewydd done and worry about Caernarfon later. I don't think uncertainty about the future choice of a Caernarfon bypass route would have any significant impact on the Bontnewydd route.

[nowster]

I don't think uncertainty about the future choice of a Caernarfon bypass route would have any significant impact on the Bontnewydd route.

Budgets, perhaps? IIRC, the cost of the Pink route (just the Bontnewydd bypass) was £60M and the Purple one is £80M. Most of that, I suspect, is the cost of admin surrounding the schemes. My notes are not here, but I think the build dates were 2016-2018.

There are two substantial viaducts needed (from the video): one over Afon Gwyfrai west of Bontnewydd (all options), and a bigger one over the Afon Seiont near Pont Rug (all options but the Pink one).

[nowster]

I've found my notes.

Pink route: This is the cheapest option at £40.3M (net benefit £108M). This part is common to all the routes. Starts at the A499/A487 roundabout, swings round the western side of Dinas and Bontnewydd, to rejoin the A487 at a new roundabout about half way between Bontnewydd and Caernarfon. There is a long viaduct taking the road over the Afon Gwyrfai (River Gwyrfai). The whole route is S2+1, with two lanes approaching the roundabouts, switching priorities about half way along.

Brown route: This is the next cheapest at £60.1M (net benefit £250M). The route starts as the Pink route. From the roundabout the road swings southwards to join the present unclassified county road from Bontnewydd to Caeathro, and proceeds along this towards the Llanberis road (A4086). Near the A4086 it deviates to the north of the present road and overflies the A4086 on a viaduct (over the Afon Seiont valley). The junction with the A4086 is using the stubs of the existing roads to form two T-junctions onto the new road. The new road continues northeast to join up with the roundabout on the B4366. From there it follows the existing road to Plas Menai, deviating from it to approach the Plas Menai roundabout with the A487 in a deep cutting. Only this climb will be S2+1. The rest

Yellow route: The cost of this route is £79.4M (net benefit £331M). This follows the pink route initially, then heads off east to skirt the Caernarfon Quarry and the Cibyn Industrial estate. It has a viaduct over the Afon Seiont, and meets the A4086 at a roundabout. There is no junction with the A4085. From the A4086, it continues east then turns north, going slightly to the east of the roundabout on the B4366. From there it continues until it meets the deep cutting planned for the Brown route, and so to the Plas Menai roundabout. The route is S2+1 throughout.

Purple route: The cost of this route is £86.7M (net benefit £327M). This route follows the same path as the yellow route as far as the B4366, at which point it curves northeast to meet the Port Dinorwic Felinheli Bypass at a directional GSJ (with the new bypass taking the main line). There is no access to/from the Caernarfon side of the existing A487.

For local traffic, the Brown route is best, and will be the only route offering property access.

Construction is estimated to be between 2014 and 2016.

There is also a "do nothing" option which involves turning movement restrictions and converting the old A487/A499 ("fingerpost") midi roundabout back into a T-junction.

The mooted "go the other way round Bontnewydd" route is not possible due to SSSIs and similar. The four route options presented carefully dance round ancient monuments, SSSIs and the like.

[jackal]

Brown route: This is the next cheapest at £60.1M (net benefit £250M). The route starts as the Pink route. From the roundabout the road swings southwards to join the present unclassified county road from Bontnewydd to Caeathro, and proceeds along this towards the Llanberis road (A4086). Near the A4086 it deviates to the north of the present road and overflies the A4086 on a viaduct (over the Afon Seiont valley). The junction with the A4086 is using the stubs of the existing roads to form two T-junctions onto the new road.

Interesting that even the cheapest of the full bypass options includes a new GSJ. Are the two T-junctions arranged to create a proper GSJ, i.e. so all movements can be handled with left turns to/from the new road? I expect not, and that there will be needless conflicts.

[nowster]

Brown route: This is the next cheapest at £60.1M (net benefit £250M). The route starts as the Pink route. From the roundabout the road swings southwards to join the present unclassified county road from Bontnewydd to Caeathro, and proceeds along this towards the Llanberis road (A4086). Near the A4086 it deviates to the north of the present road and overflies the A4086 on a viaduct (over the Afon Seiont valley). The junction with the A4086 is using the stubs of the existing roads to form two T-junctions onto the new road.

Interesting that even the cheapest of the full bypass options includes a new GSJ. Are the two T-junctions arranged to create a proper GSJ, i.e. so all movements can be handled with left turns to/from the new road? I expect not, and that there will be needless conflicts.

Yes, it looks as though there will be full left turn only connections (ie. a LILO without slip roads). There may even be proposed "no right turn" restrictions, but I didn't think to ask. It's not an echelon junction.

[nowster]

I've just received through the post the blueprint drawing of the routes, and overlays on aerial photos of the various options. They will be coming with me to Wolverhampton.