Funding for this research was provided by:
Trafikverket (Swedish Transport Administration (Dnr TRV 2014/49856))
Received: 10 June 2019
Accepted: 11 November 2019
First Online: 27 November 2019
Ethics approval and consent to participate
: The study has been approved by the Swedish Ethical Board in Uppsala, Sweden (Dnr 2015/016). The Swedish Ethical Board has waived the requirement that informed consent of research subjects should be obtained.
: Not applicable
: The authors declare that they have no competing interests.