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bus transport , which is still often carried out with diesel buses .
When RET wanted to switch to electric buses there were several challenges to overcome . These included the limited electric bus range and long charging times that would affect the regular service and the fact that if there were delays , buses could be left stranded with insufficient charge .
To address these challenges and ensure a smooth transition to electric buses , RET turned to the Rotterdam School of Management , Erasmus University ( RSM ) to use operational research to find a solution . The project consisted of three phases .
Phase 0 : Preparation stage
In the early stages of the project , RET ’ s main goal was to quantify the impact of electrification on the current schedule . RSM developed a simulation model of the bus network using OR techniques to analyze the impact of several factors including battery capacity , energy consumption patterns , and the capacity of the charging infrastructure .
This model evaluates how many buses would have low battery levels at the end of each day . This analysis showed that even in the most optimistic scenario with a large battery , low energy consumption and high charging capacity , multiple buses would have insufficient energy to complete all trips in the current schedule .
The simulation revealed that existing schedules couldn ’ t accommodate electric buses without major planning adjustments . As a result , RET adapted its planning , and the simulation model was used to optimize the charging strategy , accounting for bus delays . The model revealed a real-time charging approach was needed to reduce charging moments and maintain the bus service reliability .
Phase 1 : Northern network
This phase focused on the first set of 50 buses that would be electrified and put into service at the end of 2019 . The buses run on several different lines on the north side of the city , where they charge at seven different terminal stations during the day at fast chargers . At night , the buses are connected to chargers in the garage with a lower power to start the day with a full battery .
RSM focused on the development of optimized charging strategies that would strike a balance between planning that is robust against uncertainty and that avoids unnecessary use of fast chargers – which can have a major impact on the battery life and the city ’ s electricity network .
The question soon arose as to what the impact of delays would be on state-of-charge buses . If a bus misses a charging moment due to delay , this can cause the bus to get into trouble later in the day . The simulation model developed in phase 0 was extended to evaluate this impact and it showed that it was necessary to make real-time adjustments to the charging schedule . As a result , a real-time charging strategy was developed , based on the optimal offline charging schedule and real-time information , which indicates which bus should charge at which time . This provided a robust solution while the number of charging moments could be kept low .
Phase 2 : Southern network
In this phase attention shifted to introducing electric buses on the south side of Rotterdam . Unlike the first set of
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