The ultimate goals for developing hybrid power train systems are improving fuel economy, reducing emissions and providing commercially viable alternative low cost transportation solutions. To achieve these goals, during hybrid system design and development, a well defined set of targets and specifications are needed. These targets and specifications are necessary for optimizing the power train subsystems, components, successful system integration, and the development of proper control system. For developing a set of well defined targets and specifications, especially when dealing with hybrid power train systems, valid and reliable road load data and duty cycle profiles are required. This data is one of the most critical elements in sizing and control of the hybrid system components such as engines, batteries, generators, and motors. For mass transit vehicles, due to their well defined routes, the number of cycles for each route, and the number of vehicles on the same route the ability to optimize performance, fuel consumption, emission, and tailor the power train to vehicle need is higher than passenger vehicles. However, most engineering design and development efforts for hybrid mass transit power trains tend to depend on pre-published duty cycle data, or ignore it altogether, due to the lack of measured data. These practices, in many cases, produce hybrid power trains that fail to achieve the optimum performance. In this paper, we present a process for transit system duty cycle road load data acquisition following SAE standards. To demonstrate the data acquisition steps and approach some measured road load data examples are presented.