Train Length and Service Frequency Optimization: Passenger Health Expense Perspective

The urban transport rail network is represented by operational lines and associated variables such as the origin/destination matrix, ridership, and speed. In railway planning, operators always desire to maximize profit by evaluating the effects of different train lengths and service frequencies, whereas passengers aspire to minimize travel expenses. This study analyses the effects of train length and service frequency on economic expenses related to passengers’ travel expenses and the critical impact on the health costs incurred due to acute stress. An optimization model for maximizing the operator’s profit and minimizing passenger travel expenses, along with a health costs model related to travel expenses, is presented. A simplified algorithm is developed to analyse the impact of train length variation on the infrastructure cost, which is tested and compared over a set of real implemented projects. The scenarios of short trains, high frequency trains over long trains, and low service frequency are analysed. It is observed that longer trains with lower service frequencies optimize the operator’s profit and passenger travel expense for intercity travel. The findings indicate that selecting a balance factor of approximately 0.6 is crucial for maintaining optimal passenger expenses. Moreover, within the range of 0.7 to 0.9, passenger benefits reach a peak while slightly compromising the operator’s profit. It is evident that the 9-car train length with a service frequency of 16 and an optimum headway of 15 min, over a 4-hours observation duration, yields superior benefits for both passengers and operators. The effectiveness of the optimization model is further analysed with respect to the operator’s performance, which is adversely affected by keeping the frequency and train size constant during the peak and off-peak periods.