Dear Jacek, I am also interested in effect of various measures on safety. However there are not many such studies related to ITS. The most recent which I know of, come from Nordic countries and they are mostly in Swedish and Norwegian. One good example is here (with lots of references) - https://www.toi.no/getfile.php/Publikasjoner/T%C3%98I%20rapporter/2013/1289-2013/1289-2013-elektronisk.pdf
Yes, I understand. There may be other (English) studies on the web, but they are usually older... The Nordic ones are the most recent, and TOI is very renowned in this field.
But now I recalled this book - http://www.springer.com/engineering/mechanical+engineering/book/978-3-642-18371-3
It is based on the findings from this project - http://www.insafety-eu.org/results.html
Maybe you will find also something in this. Good luck!