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A487 Caernarfon to Bontnewydd Bypass

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We are proposing to build a bypass from the Goat roundabout on the A499/A487 junction to the Plas Menai roundabout, around Llanwnda, Dinas, Bontnewydd and Caernarfon avoiding the town centres.


Project status: planned
Region/county: north Wales
Start date: autumn 2017
End date: late 2019
Cost: to be confirmed
Employers agent: EC Harris, Ramboll
Design and build contractors: Balfour Beatty, Jones Brothers (Ruthin)
Designers: WSP and Parsons Brinckerhoff, TACP

Contact Bryn Williams, Public Liaison Officer, on 07786 513571 or via the contact form, to arrange a meeting or ask a question about the project.


Why we are doing it

This project is attempting to address the following issues:

  • Traffic volumes are increasing, causing traffic congestion and increasing journey times.
  • Poor road infrastructure, particularly poor connections to Bangor and the A55, may be hindering economic development.
  • Quality of life in the settlements alongside the A487 is adversely affected by the high volumes of traffic.
  • There is a high risk of collisions in urban areas, particularly with heavy goods vehicles accessing Cibyn industrial estate and vehicles travelling at inappropriate speeds.
  • Vehicles use unsuitable country roads to bypass the A487.
  • Road maintenance is difficult due to high traffic levels and lack of suitable alternative routes.

If we do nothing traffic flows are predicted to increase causing the following problems:

  • longer queues at the A499/A487 Goat roundabout
  • higher volumes of vehicles passing through settlements along the route
  • queues and delays on the A487, particularly at Eagles Junction, St David's and Morrisons roundabouts in Caernarfon, and at Plas Bereton.

Current progress

WelTAG Stage 1 Appraisal was undertaken in 2008. From this, 4 options for improving traffic in the area were considered:

  1. New bypass Llanwnda to Plas Menai.
  2. 'Local' bypasses for Dinas, Bontnewydd, Pont-rug, Crug and a new link to the Cibyn industrial estate.
  3. Conventional rail provision.
  4. A package of measures to include road traffic management, parking, accident remedial measures, bus priority and service levels, cycle provision and pedestrian areas/crossings.

In 2009 we appointed Parsons Brinckerhoff and TACP to undertake the WelTAG Stage 2 Appraisal for the scheme. This involved the appraisal of 4 bypass options through traffic, safety and economic assessments. These 4 routes along with 7 suggested by the public underwent a detailed appraisal including whether they were technically and operationally feasible; their environmental impact and sustainability; whether they were affordable and deliverable; and their safety.

We announced the Purple Option as the preferred route in November 2010. In light of budgetary pressures we carried out a review of options and withdrew the original preferred route and announced the Yellow Option as the preferred route.

The contract for the project was awarded to Balfour Beatty and Jones Brothers (Ruthin) in December 2014. They will be supported by WSP Parsons Brinckerhoff and TACP as their technical and environmental advisors.

The scheme proposals have been developed in consultation with stakeholders and Public Information exhibitions were held in March and July 2015.

We published draft Orders, environmental statement, and other associated reporting in August/September 2016 and held exhibitions in September to explain the proposals to the public.

A Public Local Inquiry into the Scheme will start on 13 June 2017 and is expected to last around 4-5 weeks.

At the Public Local Inquiry an independent inspector will examine the social, environmental and economic issues and hear evidence from technical specialists, supporters and objectors.

The inspector will consider the Scheme and all suggested alternatives and report on the findings.

Why hold a public local inquiry?

At a public local inquiry an independent inspector examines the social, environmental and economic issues and hears evidence from technical specialists, supporters and objectors. The inspector will consider the proposed solution and all suggested alternatives and report on the findings. This will inform the final decision on whether to go ahead with construction.

The plan

The scheme is being developed to meet 5 objectives:

  • reduce journey times between Llanwnda and Plas Menai
  • reduce journey times between Llanwnda and Caernarfon
  • reduce the number of vehicles passing through residential communities including Llanwnda, Dinas, Bontnewydd and Caernarfon
  • reduce accidents on the A487
  • improve the resilience of the network by increasing the amount and/or capacity of alternative routes.

The plan is to build 9.8km 2+1 carriageway (2 lanes in one direction, 1 in the other, switching from one side to another) between the Goat roundabout and Plas Menai roundabout. The route will:

  • create a western bypass to Llanwnda, Dinas and Bonewydd
  • cross the existing A487 south of Caernarfon
  • cross Afon Seiont
  • pass south of the Cibyn industrial estate to form a junction with the A4086
  • cross the B4366.

Preferred route Preferred route

It will involve constructing 22 structures including culverts and 7 bridges. The bridges will be:

  • a crossing over the Welsh Highland Railway
  • a 300m viaduct over Afon Seiont
  • a 280m viaduct over Afon Gwyrfai and its flood plains
  • 4 bridges carrying existing roads under or over the new road.

75% of the cost of the scheme will be spent with local Welsh suppliers.

We will also improve the existing A487 to improve existing junctions.


Public consultation exercise: 2010-2011
Preferred route announced: May 2013
Appointment of contractor: December 2014
Site investigation and surveys: February 2015 - December 2015
Preliminary design: December 2015
Orders exhibition: autumn 2016
Public local inquiry: June 2017
Start of bypass construction: autumn 2017
Bypass opening: late 2019
Completion of existing junction improvements: mid 2020

How we are consulting

Four bypass options were presented to the public as part of a consultation exhibition in March 2010. 972 people attended these exhibitions and 498 completed questionnaires were received. The responses from these questionnaires demonstrated that the public was in favour of a bypass. Further consultations took place towards the end of the year before we announced our preferred route.

We are consulting on the project over the next year in order to define the final designs. The consultation includes public exhibitions and discussion with the project public liaison team. Computer-generated models will be used in the public consultation process.

Public exhibitions have already taken place in March and June 2015. We have held meetings with landowners to understand the likely impact of the scheme of properties and businesses in the area.

Contact Bryn Williams, Public Liaison Officer, on 07786 513571 or via the contact form, to arrange a meeting or ask a question about the project.

Next steps

The inspector will report on the findings of the Inquiry and this will inform the final decision on whether to go ahead with construction.

Document Download

Adobe PDF document
Proposed design plans (File size: 9.5MB)
Adobe PDF document
Scheme assessment report (File size: 6.7MB)