The punctuality and the reliability of public transport are key factors in the choice of travel mode, and they also affect operating costs. When travel time on a route varies significantly, public transport operators need to increase scheduled buffer time to maintain punctuality and reliability. This increases costs by increasing staffing and equipment needed to offer a given level of service. The variability in route travel time depends on many factors, including traffic conditions, number of passengers, and operating practices (e.g., boarding processes). A study was done to evaluate the impact of one boarding subprocess, ticket sales, on bus dwell time at stops. The research confirmed that onboard ticket sales can significantly affect a public transport line's travel time and reliability. The research showed that onboard ticket sales subprocesses are relatively long and vary significantly; consequently, they strongly influence schedule reliability. Results showed that the time spent selling tickets can be up to 20% of the total run time. However, the biggest problem is the great variance in time spent on the ticket sales process.