N2 Slane Bypass - County Meath

Roughan & O’Donovan N2 Slane BypassConsulting Engineers Environmental Impact Statement - Non-Technical Summary

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N2 Slane BypassNon-Technical Summary of the Environmental Impact Statement

TABLE OF CONTENTS

Part IBackground Information and General Description

1.0 INTRODUCTION .............................................................................................. ii2.0 BACKGROUND TO THE SCHEME ................................................................. ii3.0 SCHEME DESCRIPTION ................................................................................. v4.0 ALTERNATIVES CONSIDERED .................................................................... vi5.0 TRAFFIC IMPACTS ....................................................................................... vii

Part IISignificant Environmental Effects and Proposed Mitigation

Measures

6.0 HUMAN BEINGS ........................................................................................... viii7.0 THE NATURAL ENVIRONMENT .................................................................. viii8.0 LANDSCAPE AND VISUAL IMPACTS ............................................................ x9.0 MATERIAL ASSETS IMPACTS ...................................................................... xi10.0 ARCHITECTURAL, ARCHAEOLOGICAL AND CULTURAL HERITAGE...... xi11.0 MITIGATION MEASURES ............................................................................. xii12.0 FURTHER INFORMATION ............................................................................ xii13.0 WHAT HAPPENS NEXT? ............................................................................. xiii


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Part IBackground Information and General Description

1.0 INTRODUCTION

This Environmental Impact Statement for the proposed N2 Slane Bypass has beenprepared by Roughan & O'Donovan, Consulting Engineers on the instruction ofMeath County Council National Roads Design Office.

The purpose of the proposed N2 Slane Bypass is to overcome major road safetyproblems on the N2 route that passes through Slane Village. It is required toovercome the inadequacies of the existing road network through provision of a localbypass of the village of Slane, where the existing road layout on the N2 ishazardous for traffic.

A bypass of Slane village is an objective of the Meath County Development Plan(2007 – 2013). The location of the scheme can be seen in Figure 2.1.

2.0 BACKGROUND TO THE SCHEME

2.1 Existing Road Network

The existing road network through Slane is dominated by the N2 and N51 NationalRoutes, both of which currently pass through the centre of the village.

The N2 National Primary Route is a strategic corridor from Dublin to the Northand to the border counties that runs south to north through Slane.The N51 National Secondary Route runs east to west linking Drogheda andDelvin via Navan. (See Figure 2.1 for Location Plan).

The existing N2 National Primary Route crosses the River Boyne via a multi-archedmasonry bridge at the southern edge of Slane village as shown in Photos 2.1 and2.2. The bridge is restricted in width and unsuitable for two-way heavy goodsvehicle traffic as shown in Photo 2.3. To regulate traffic flow, there are trafficsignals that give alternating priority to Northbound and Southbound traffic.

The approaches to Slane Bridge are very steep, especially on the northern side withgradients of nearly 10%, which far exceeds the desirable maximum gradientrecommended in the National Roads Authority Design Manual for Roads andBridges (NRA DMRB). The road also turns through sharp bends at both ends of thebridge, making the existing road layout at Slane Bridge hazardous. There havebeen numerous traffic accidents, some fatal, over the years, typically when heavygoods vehicles (HGV’s) descend on the steep hill and collide with other traffic orcrash through the bridge parapet.

In 2002, a scheme to improve traffic safety was installed on the steeper southboundapproach to the bridge, with additional traffic signals on a two-lane system regulatedby overhead gantry signals to separate trucks from light traffic as shown in Photo2.4. These current safety measures have been successful in reducing thefrequency and severity of accidents at Slane Bridge. However they are considered


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to be interim arrangements pending the provision of a bypass for Slane on the N2route, which should remove a large proportion of traffic from the unsuitable sectionof road over the bridge.

Further traffic hazards exist on the N2 route through Slane, where the steepgradient extends through the centre of the village and the signal-controlled cross-roads at the N51 junction. A recent multi-vehicle accident occurred in March 2009when a truck travelling southbound collided with stationery traffic waiting at theN2/N51 junction traffic signals. Fortunately there were no fatalities or major injuriesas a result of this accident, but it could have been much worse. Further traffic risksarise near the primary school near the top of the hill towards the northern edge ofthe village, with large volumes of truck traffic passing in front of the school entrance.

Public concerns about traffic safety in Slane are high, and there is strong localdemand for a bypass to reduce through traffic volumes, especially of trucks, whichare considered to pose a severe risk on the steep hill through the village on the N2route.

Photo 2.1 – View of Slane Bridge from the Southern Approach (View North)


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Photo 2.2 – Existing Slane Bridge over the River Boyne (view from south east)

Photo 2.3 – The Existing Slane Bridge (View from north side of bridge)


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Photo 2.4 – Interim Traffic Management and Safety Measures at SouthboundApproach to Slane Bridge (View Northward)

2.2 The Need for the Scheme

This section of the N2 National Primary Route has a poor safety record with a highnumber of accidents having occurred at Slane Bridge and in the village. It isdesirable for a more suitable bridge crossing of the River Boyne to be provided atSlane so as to reduce the accident risks on the existing route.

2.3 Function of the Proposed Scheme

The primary objectives of the N2 Slane Bypass scheme are:(a) To improve traffic safety by removing through traffic from the existing route

through Slane Village and over Slane Bridge;(b) To improve the environment of Slane Village by removing a significant portion

of north/south through traffic;(c) To obtain an improved level of service suitable for a National Primary route;(d) To achieve an objective of the Meath County Development Plan 2007 – 2013.

3.0 SCHEME DESCRIPTION

The proposed N2 Slane Bypass will pass to the east of Slane village. The southernlimit of the scheme will be located a short distance north of McGruder’s Cross atJohnstown. The northern limit of the scheme will be located a short distance northof the edge of Slane Village where the existing N2 follows a vertical sag curve in thetownland of Mooretown. The scheme is approximately 3.5km long and will cross theRiver Boyne on a new bridge at a location approximately 1.1km to the east of theexisting N2 Slane Bridge.


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The N2 Slane Bypass will include from south to north the following elements:

N2 South Roundabout to form a junction at the southern extent of the schemeto connect to the existing N2 at Johnstown;An overbridge where the new N2 will pass under the Rossnaree Road(L16002) at Fennor including slight vertical realignment of this local road;A major 200m long bridge crossing of the River Boyne.A Roundabout junction at N51 at Cashel, about 1.2km east of the existingN2/N51 junction in the centre of Slane Village, with realignment of the existingN51 over a length of 700m;N2 North Roundabout to form a junction at northern extent of scheme toconnect to the existing N2 Mooretown;Various accommodation works for affected land-owners.

The overall route of the proposed N2 Slane Bypass is illustrated in Figure 3.1 to3.3.

4.0 ALTERNATIVES CONSIDERED

The proposal for the N2 Slane Bypass has progressed through a number of stagesincluding the Constraints Study, followed by the Route Selection Study, which hasnow been followed by preliminary design of the Preferred Route Option. Theassessment of several alternative Routes considered the following factors:

Engineering suitabilityTraffic SafetyTraffic ImpactArchaeology and Cultural HeritageEcologyLandscape and Visual impactAgricultural Land-UseGeology and HydrologyEconomics

Following detailed investigations an eastern bypass was considered the favourableoption. The Preferred Route was further developed during the preliminary designstage to provide the best route possible in environmental, engineering andeconomic terms.

The following road types were considered for the N2 Slane Bypass in accordancewith the traffic capacity requirements in the context of an overall route strategy forthe N2 between Ashbourne and Ardee:(a) Standard Single Carriageway (12.3m wide);(b) Type 2 Dual Carriageway (16.5m wide);(c) Motorway with Standard Dual Carriageway (21.5m wide).


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A Type 2 Dual Carriageway was selected as the most appropriate road type interms of providing reserve capacity for long-term traffic growth, the greatest degreeof overtaking opportunity and associated road safety and best overall value in costterms.Four possible bridge heights ranging from 12m to 35m above river bank level wereassessed for the River Boyne crossing. A mid-level bridge of approximately 19mheight was selected as the best balance between cost and environmental impact.

5.0 TRAFFIC IMPACTS

The proposed Slane Bypass will significantly improve traffic safety in Slane Villageby diverting most through traffic away from the steep north-south N2 route. This willgreatly enhance the residential amenity within Slane Village. In particular thebypass will greatly reduce the number of heavy goods vehicles that pass throughthe village and cross Slane Bridge, which should remove the existing risk of fataland serious accidents on the steep hills through Slane and approaching the bridge.

(a) The proposed bypass is forecast to carry a design year traffic flow of betweenapproximately 10,000 and 12,300 AADT in 2027.

(b) A Type 2 Dual Carriageway is the most suitable road type for the N2 SlaneBypass to provide a sufficient reserve of traffic capacity for the future.

(c) The bypass will divert up to 75% of the traffic along the existing N2 throughSlane Village.

(d) Residual traffic flows on the N2 South of the Square and across Slane Bridgeroute will reduce by 94% from 9,200 vehicles per day to 700 vehicles per day.

(e) Residual traffic flows on the N2 north of the Square will reduce by 54% from8,100 vehicles per day to 3,700 vehicles per day.

(f) Truck flows across Slane Bridge will reduce by 1,400 per day, which will havevery significant benefits in the village in terms of public safety.

(g) Traffic on the N51 is expected to increase moderately (+13%) with trafficbetween the N2 South and N51 West diverting to the Bypass.

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N2 Slane Bypass - County Meath