Dr. Ruth's main research interests are in the field of multimodal transport, international logistics, trade facilitation & logistics development policy and supply chain performance measurements. He has published over 100 papers and reports in such journals as International Journal of Physical Distribution and Logistics Management (IJPDLM), International Journal of Logistics Research and Application (IJLRA), Supply Chain Management: An International Journal (SCMIJ), European Journal of Marketing (EJOM), Asia Pacific Journal of Marketing and Logistics (APJML), Journal of Applied Sciences (JAS), Maritime Policy and Management (MPM), Asian Journal of Shipping and Logistics (AJSL), among others, and he has co-authored more than 10 books.

Since 1995, Ruth has been a consultant for international agencies such as the United Nations Conference on Trade & Development (UNCTAD), the United Nations Economic and Social Commission for Asia and the Pacific (UNESCAP), The World Bank, The Asian Development Bank (ADB), The Association of South East Asian Nations (ASEAN), etc.

He received his PhD in 2001, in the field of International Logistics within the Logistics & Operations Management Section (LOMS) at Cardiff Business School (UK). He was the winner of the James Cooper Cup in 2001 for the best PhD dissertation in logistics from the Chartered Institute of Logistics & Transport (CILT) in the United Kingdom. In 2016, Supply Chain Asia (Singapore) awarded the prize of supply chain educator of the year to Ruth.