Ten-mile tailbacks on the N11 south of Kilmacanogue, Co Wicklow, during the recent cold spell, were not caused by a failure to detect bad weather or to grit the road, Wicklow County Council said yesterday.
Snowfalls on routes through Kilmacanogue and Windgates and on the Sally and Wicklow gaps left motorists queuing for up to three hours to get from Co Wicklow into Co Dublin on Wednesday morning.
Bus services were also restricted with the 84 running into difficulty on Bray Head and the 44B out of service until further notice. The 44 from Dublin to Enniskerry ran only as far as Kilternan on the Wicklow border.
Commuters were exasperated after routes out of north Wicklow again became severely congested yesterday leaving thousands of people hours late for work in Dublin for the second day in a row.
More than 50,000 vehicles a day use the N11, passing St Valerie's Bridge at Kilcroney, between Bray and Enniskerry. About a third of that number would travel in the morning peak from 7.30am to 9.30am.
But as tailbacks stretched from there to the Ashford Rathnew bypass for the second day in a row, Wicklow council countered criticism from frustrated motorists saying a range of technology, salt and grit had been used to keep the roads open.
Council senior administrative officer Christine Flood told The Irish Times that three crews had gritted the N11 twice from midnight Tuesday and into Wednesday morning. On Wednesday night three crews again gritted the northern section of the N11 at midnight and again at 4am. The southern section from the Tap pub to Arklow was gritted three times during this period, she said.
Wicklow council bases its gritting strategy on the National Roads Authority's Icecast system, a technology with monitors embedded in national roads which warn if a freeze is imminent. The optimum time to grit is one hour before freezing.
But this week the continual falls of snow made the system less effective. Ms Flood said the roads were gritted and salted at midnight and 4am but the light snow kept falling, washing away the salt. The southern section was gritted again at 6am but then the cars compacted the snow. "Obviously the work must be done when the roads are free, but the window between freeze and snowfall can be very small," she said.
