The National Roads Authority has said it remains "extremely reluctant" to install median barriers on the M50 before the expansion of the motorway, due to begin next year.
Following a three-car pile-up on the M1 motorway near Dublin Airport earlier this month, the authority said it would immediately "retro-fit" crash barriers on all motorways - with the exception of the M50.
The M50 was not included because work on the expansion of the ring road to three lanes in each direction is due to get under way early next year.
The authority believed there would be little point in fitting the barriers and taking them out again when work begins.
However, the expansion of the motorway to three lanes is to be done on a phased basis with only the section between the N4 Palmerstown junction and the Red Cow Interchange with the N7, starting next year.
Work on installing a third lane on the rest of the M50, including the scene of yesterday's crash, is not due to start until early 2006, in about 15 months time.
The location of yesterday's crash, north of the Blanchardstown interchange, is just two kilometres from the Finglas flyover of the M50, where three men lost their lives in a "cross over" accident in March 2001. Mr Jason Nugent (19) of Fortlawn Drive, Blanchardstown, and Mr Robert Fitzsimons (27), of Whitestown Park, Blanchardstown, were killed when their vehicle crossed the central reservation and struck another vehicle being driven by Father David Boylan (35), of Crumlin. Father Boylan was also killed.
The incident prompted calls for crash barriers across the central reservation of the M50 to replace the grass verge.
Defending the safety record of the road at the time, the NRA's head of corporate affairs, Mr Michael Egan, said that in the five years up to the 2001 crash only two people had been killed on the M50.
The three men brought that number to five. A sixth man was killed on the same stretch of road in November 2003 in a single vehicle accident but this did not involve the vehicle crossing the central reservation.
Yesterday, Mr Egan told The Irish Times: "I would be very reluctant to put in a barrier and take it out again when construction starts."
He said that despite the crashes the M50 was built to the highest standards of road safety and that motorways were still the safest roads in the State, "far safer than separating traffic by painting a white line on the road".
Out of more than 90 million journeys on the M50 in the five years prior to the three deaths in 2001, there had been just one other fatal accident, he said. This had involved two people.
The NRA position has been supported by Dr Donncha Ó Cinnéide, of University College Cork, who earlier this year showed in a study of road accidents over four years that motorways were the safest roads.
Three-lane roads with climbing lanes were particularly dangerous, he and his team found, with a fatal accident rate eight times that of motorways.
About 10 per cent of all injury accidents on three lane roads resulted in fatalities. Undivided roads were six times more dangerous than motorways and dual-carriageways were three times more dangerous.
