The take-up of travel plans is increasing across the National Health Service (NHS) in the UK, yet their impact on reducing car use is relatively low. Previous studies have investigated the determinants of generic travel plans but lacked an appreciation of the unique context of healthcare settings. This study investigated NHS travel plan co-ordinators’ views on hospital travel plans to identify the factors affecting the success of travel plans in changing travel mode choice behaviour. A nationwide survey was conducted among NHS travel plan co-ordinators in England, with a response rate of 51% (n = 47). Findings suggest that despite having the potential for promoting walking as a key travel option among the hospital staff, measures to promote walking were reported as the least effective. Spearman correlation tests show that the effectiveness of measures to promote walking and reduce car use was positively associated with each other – highlighting the significance of designing effective travel measures to promote walking to attain the overall success in changing travel mode choice behaviour. Shift working patterns, personal circumstances, high car use, and staff attitude towards car use were reported as the key barriers to change travel mode choice behaviour among the NHS hospital staff. The use of robust methods, and evidence-base to develop, and monitor travel plan measures were found to be the key determinants of the success of travel plans. The provision of off-site car parks around 10–15 min walking distance away from the hospital site will not only encourage the car users to walk, but also provide a realistic solution to the transport issues experienced by the hospitals. This study contributes to the knowledge gap by providing a valuable insight into the factors that may have affected the success of hospital travel plans, and form a basis for future research.