Australia

Department of Transport

Brazil
National Land Transport Agency

Britain
Department for Transport
HM Railway Inspectorate
Office of the Rail Regulator
Railway Safety
Strategic Rail Authority (SRA)

Canada
Canadian Transportation Agency
Transport Canada (ministry)
Transportation Safety Board

Denmark
Ministry of Transport
National Rail Authority

China
Ministry of Railways

Europe
DG Tren (EC Directorate General Energy & Transport)
European Commission Systems for Advanced Management of Public Transport Operations (SAMPO)
European Conference of Ministers of Transport (ECMT)

France
Ministry of Transport

Germany
Federal Ministry of Transport
Federal Railway Authority (EBA)

Italy 
Ministry of Transport and Navigation

Japan
Ministry of Transport

Lithuania
Ministry of Transport

Netherlands
Ministry of Transport

Norway
Ministry of Transport and Communications
National Accident Investigation Board (rail)/a>
Norwegian Railway Inspectorate

Russia
Ministry of Railways

Singapore
Land Transport Authority

Slovakia
Ministry of Transport

Sweden
Rikstrafiken (franchising authority)
Transport Styrelsen (Swedish Transport Agency)

Taiwan
Bureau of Taiwan High Speed Rail (BOTHSR)

USA
California High Speed Rail Authority
Caltrans Rail Program
Federal Railroad Administration
Federal Transit Administration (FTA)
Surface Transportation Board (STB)
Transportation Research Board (TRB)
US Department of Transportation (DOT)