This feature briefly describes Cork Corporation's proposals for the grade separation of the Kinsale Road Roundabout.
The Kinsale Road Roundabout is a five-arm signalised junction and is located approximately 3 km south of Cork City at the junction of the N25 South Ring Road, the N27 Airport Road/Frankfield Road and the South City Link Road. The South Ring Road has been constructed on a phased basis over the last 10-12 years. The completion of the downstream crossing, the Jack Lynch Tunnel, has led to a marked increase in traffic using the South Ring Road which in turn has led to increased delays at the Kinsale Road Roundabout. The South Ring Road is currently a dual 2 lane carriageway with a number of at-grade and grade-separated interchanges located along its length. Cork Corporation, in conjunction with The National Roads Authority is currently carrying out road improvements on the South Ring Road which will upgrade the carriageway between the South Douglas Road Interchange and the Kinsale Road Interchange from a dual 2 lane carriageway to a dual 3 lane carriageway. During the morning peak period significant queues develop on all approaches to the Kinsale Road Roundabout, particularly on the Airport Road, Frankfield Road and the South Ring Road in both directions. During the evening peak period queues are generally concentrated on the approaches to the roundabout from the South Ring Road. Recent traffic counts have shown that there are in excess of 85,000 vehicles using the roundabout daily. The straight-through movement between the east and westsidesoff the South Ring Road was the highest recorded traffic movement at the roundabout and represents approximately 40% of the total traffic using the roundabout.
The need for the scheme therefore is to alleviate the congestion at the roundabout.
In the determination of a preferred scheme solution a number of options were developed and evaluated in terms of environmental impact, safety, constructability, cost, aesthetics, disruption to traffic during construction and landtake. These options included:
Having compared and evaluated the four options it was considered that a flyover carrying the N25 South Ring Road over the existing roundabout was the most suitable solution.
It is proposed to construct a flyover carrying the N25 South Ring Road over the existing roundabout thus removing the traffic that wishes to travel east/west along the South Ring Road from the other traffic movements on the roundabout.
The flyover will be formed using reinforced earth embankments and a central bridge structure crossing the roundabout. The reinforced earth type embankment has been adopted because of the limited space required to construct it and it involves least disruption to traffic during construction. Several span options were considered for the flyover structure.
Slip roads will be constructed to provide access to and from the South Ring Road to the roundabout. The junction of Frankfield Road and the Airport Road will be improved. The dedicated westbound slip road from the junction of the Frankfield Road and the Airport Road will be realigned southwards to facilitate merging with the westbound on slip.
The scheme is being designed to minimise the disruption to traffic during construction. The south-western and south-eastern slip roads will be built in the grassed area south of the existing South Ring Road. Once constructed they will take the westbound traffic. The eastbound traffic will be diverted onto the existing west-bound slip roads so that the new north-eastern and north-western slip roads may be built.
When the new slip roads are constructed and the traffic is flowing on them the flyover will then be built in between. The bridge structure spanning across the roundabout will comprise a reinforced concrete slab on steel box girders. The steel box girders will be prefabricated off site and erected during night-time closures of the roundabout.
While every effort will be made to minimise disruption to traffic it is however likely that the delays at the roundabout will increase during the construction period.
An Environmental Impact Statement has been published. The purpose of the Environmental Impact Statement is to report on the impact of the proposed development on the environment in terms of air quality, noise and vibrations, landscape and visual aspects, nature conservation and land use, soils and geology, hydrology and hydrogeology, archaeology and cultural heritage, socio-economics, planning etc. A Non-Technical Summary of the Environmental Impact Statement for the Grade Separation of the Kinsale Road Roundabout on the Cork South Ring Road (N25) may be viewed in PDF format.
It is anticipated that construction will commence on site in 2002 and will take two years to complete.
Further information maybe obtained from: -
The National Roads Office,
Tel. No. 021 4821046
Fax. No. 021 4866209