I've been in your position, a number of years ago. See my post on
this thread for info on expenses.
It will be up to the local Garda Superintendent as to whether to prosecute or not. If there are no other witnesses, s/he will decide on the basis of the statements - assuming the other party does make a statement - they may not.
If it does go to court, you may be approached by the Super regarding a reduced plea. My case went to appeal and, second time round, his counsel made a plea, through the Super, for agreement on a reduced charge. I agreed - in hindsight, I probably shouldn't have, but I wasn't expecting the approach.
Nevertheless, in the initial case, I had to give evidence under cross-examination. Be prepared for the other parties solicitor to do everything to undermine your evidence - it's their job to do so. If it does come to court, refamiliarise yourself with that particular stretch of road and note any changes since. The other parties solr/engineer/whatever will do this anyway.
In my case, during the initial hearing, the "plonker" started argueing (gave the impression he thought that they were thick!
) with both the Super and the judge. Afterwards a Garda told me that, on the way to the court, the stupid git - this guy put great emphasis in court and outside, that he was "a company director" (multinational) - had actually overtaken the Judge's car at speed, crossing a contiouous white line!
Easy for me to say, but, if the case goes ahead, then drive on! It may be a small town, but while people who drive dangerously are allowed to continue to do, our small towns will, all too often, get a little smaller.