The controversial Glen of the Downs dual carriageway has generated more than 16,000 letters between the contractor and Wicklow County Council over variations to its contract.
The road widening scheme, which has been delayed by a further two months is set to cost up to 90 million, nearly double its original estimate.
The latest completion date for the four-mile stretch of road had been the end of last month, but the contractor, Ascon, has indicated that further delays to the project will postpone its opening until the end of October.
Yesterday a spokeswoman for the National Roads Authority said that a "paperwork" delay in the approval of median crash barriers was the reason behind the latest hold-up.
A spokeswoman for the council blamed the latest hold-up on the fact that the contractor was unable to close off some roads in order to speed up the final stages of the construction project. She confirmed that the contract had generated more than 16,000 pieces of correspondence, mostly over contract variations.
The rising cost of the project has been blamed on this, with delays and changes caused by a number of factors. A specialist arbitration firm has been brought in to analyse these extra claims.
New ecological measures to protect a stream had to be taken, while 60 different archeological sites were found during the work.
The project has been slowed by the fact that roughly 30,000 cars pass through the site each day. The four-mile €85 million road was initially delayed by an eco-warrior protest in the glen, who took a failed High Court action against the project.
Work began in June 2000 and was expected to have been completed by the end of last year. The NRA said it hoped the road would be open by mid-summer, but this was then changed to mid-September. Another major problem encountered during construction included the replacement of two large watermains which bring water from Roundwood to Dublin. The replacements led to 20 separate water cut-offs over the past three years.