A relatively recent timeframe of application.
The Directive was brought into force only recently (December 2011).
In addition, its provisions deal with road infrastructure, e.g. an area where interventions have long life-cycles and their subsequent changes take time to produce their effects.
In particular, this holds true given the current public budget constraints that limit the number of newly undertaken road investments.
This complicated the evaluation of the effectiveness of all RISM measures, namely of those that are applied to new roads (e.g. RSIAs and RSAs although the latter one are applied to existing roads as well).