Author: Paul MacDonald, CEng MIEI, executive engineer/training officer, Kildare National Roads Office
The Dublin Tunnel is a 4.5km-long, twin-bore tunnel connecting Dublin Port to the M50 Motorway ring. The tunnel was proposed by Dublin City Council in order to remove heavy goods vehicles from the city centre for safety and environmental benefits. The tunnel project was funded by Dublin City Council, the National Roads Authority and the European Union. The Dublin Tunnel is a unique business selling point for Dublin Port companies, given the ease of access to and from the port via the tunnel.
The Dublin Tunnel construction was completed in 2006. The operation and maintenance (O&M) of the tunnel has been performed for the National Roads Authority by Egis Road and Tunnel Operation Ireland (ERTO), a subsidiary of the French infrastructure firm Egis Road Operation since 2006. The Dublin Tunnel, and the Jack Lynch Tunnel in Cork, are managed from the Tunnel Control Building located at the southern entrance to the tunnel near Dublin Port.
[caption id="attachment_17850" align="aligncenter" width="1498"] Dublin Tunnel toll plaza (copyright Thomas Graham Arup)[/caption]
The safety record in Dublin Tunnel is excellent, with no accident fatalities since the opening. The availability level is 98% for road users, excluding planned night closures for maintenance. The annual average daily traffic (AADT) through the Dublin Tunnel is approximately 15,000 vehicles per day, with a steady 6% annual increase in traffic over the last few years – reflecting increased activity levels in the Irish economy.
The original predicted percentage of heavy goods vehicles using the tunnel was estimated to be 60% of the total traffic. However, the actual percentage has been lower than expected with approximately 40% of the traffic being heavy goods vehicles. The remaining 60% of traffic consists of cars and other vehicles that utilise the tunnel for time-saving benefits.
Heavy goods vehicles (vehicles above 3.5 tonnes and buses above 25 seats) can use Dublin Tunnel free of charge, given the ban on these vehicles in Dublin city centre. Cars and other vehicles are obliged to pay time-period-related tolls, which are substantially higher at the peak hours (6am to 10am southbound Monday to Friday and 4pm to 7pm northbound Monday to Friday). The tunnel is closed to traffic during the maintenance periods on three nights of the month to enable maintenance of tunnel equipment, infrastructure and systems.