[IQP] Evaluating Pulse Scheduling in the Strætó Bus System

Kyle France
Suverino Frith
Veronica Melican
Samuel Moran

Abstract: The public bus system in the Capital Region of Iceland, operated by Strætó bs, uses pulse scheduling, where buses from multiple routes meet at a common station at about the same time to facilitate convenient transfers. However, factors such as traffic congestion and rider boarding behavior have caused frustrating delays in the system. The goal of this project was to evaluate Strætó’s pulse scheduling and develop recommendations to improve the service. We collected and analyzed data about the logistics of rider transfers made in the bus system and gathered stakeholder perspectives. Our research confirmed that pulse scheduling may no longer be the best strategy for Strætó. Our primary recommendation was that Strætó remove pulse scheduling and increase frequency to improve rider satisfaction.

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Executive Summary

A sustainable public transportation infrastructure is a key element in the development of cities worldwide. Public transportation systems can reduce automobile dependency and thus reduce traffic congestion in a city by providing a safer and less expensive alternative to cars. An effective public transit system allows people and resources to flow smoothly through a city, facilitates access to resources and trade markets, and improves the quality of life for individuals by enabling them to easily reach services such as education and healthcare (Bamwesigye & Hlavackova, 2019). The United Nations recognizes the value of public transportation in its sustainability goals for 2030. Part of the eleventh goal states that by 2030, cities should “provide access to safe, affordable, accessible and sustainable transport systems for all, improving road safety, notably by expanding public transport” (United Nations, n.d.).

Iceland’s public transportation system consists of a bus network operated by the company Strætó bs. Strætó’s network includes four major connecting stations operating on a “pulse” schedule, meaning buses from multiple lines arrive and depart at about the same time to minimize transfer times between buses (Strætó bs, 2019d). However, increased delays in Strætó’s system since the implementation of the pulse scheduling have caused frustrations for riders. Strætó is considering modifying pulse scheduling to reduce costs and make transfers more convenient for passengers. The goal of this project was to evaluate the efficiency of pulse scheduling in the context of Strætó’s overall public bus system and to develop recommendations for the system’s improvement.

Public transit is a valuable part of urban communities, but providers have limited resources so they must prioritize carefully in order to provide the best service possible. This balance includes determining which services reach the most customers and which services are necessary to provide despite low ridership. Public transit providers must also balance the performance of their network with factors like coverage and service availability to preserve the highest priorities of the rider base. Effective planning of a transit system requires information about the behaviors and perceptions of passengers who use it. To give Strætó more information, this project investigated the performance of Strætó’s pulse scheduling in terms of employee perspectives, passenger satisfaction, and bus timeliness.

Our strategies included gathering data about bus transfers made within the system and analyzing bus timeliness data to understand the logistics of pulse scheduling. We also conducted interviews with Strætó employees and interviews and a survey of riders to gain stakeholder perspectives. Finally, we conducted a SWOT (Strengths, Weaknesses, Opportunities, and Threats) analysis to identify the pros and areas for improvement of pulse scheduling.

Results and Discussion
Analysis of our data revealed some general trends about the logistics and perceptions surrounding pulse scheduling in Strætó’s system. Our data reinforced the idea that pulse scheduling is no longer the best strategy due to an increase in schedule delays in recent years. At each pulse station observed, we noticed that two to three bus transfers were utilized more than others. For example, at Hamraborg, roughly three times as many passengers transferred between buses #1 and #4 versus buses #2 and #4. While many riders remarked that the pulse scheduling is convenient when it works as planned, they also reported that the frequent delays are very frustrating.

Responses to our survey showed that the most common reason (38% of respondents) that passengers found transfers at pulse stations to be inconvenient was that buses arrived late, causing passengers to miss the bus they had planned on transferring to. Figure 2 shows a bus stuck in traffic, which is one cause of delays. Our data about bus arrival times showed that at each station we examined, more than 12% of all buses arrived late across all times of day. At Ártún, the station we observed with the most delays, 42% of buses arrived late during the afternoon rush hour. This problem is not isolated to a single route or station, but rather affects routes across Strætó’s network. The specific causes of the delays we observed was not a focus for our work but could be an area for future research teams to investigate.

A fleet manager at Strætó commented in an interview that pulses sometimes cause delays in the system to propagate as buses on a pulse wait for a straggling bus to catch up. Removing the need for buses to wait for each other could help to reduce the scheduling issues caused by traffic and by other factors. In this way, the removal of pulses would not prevent buses from falling behind schedule but might isolate delays to improve the efficiency of the overall system.

The rider survey showed that waiting a few minutes for a bus to make a connection was the least commonly cited reason (only 6% of respondents) for transfer inconvenience at all three pulse stations in question. Based on this information and discussions in our informal rider interviews, a schedule without pulses in which popular routes arrive only a few minutes apart (but do not necessarily wait for each other) would keep transfers mostly convenient for riders while saving Strætó an estimated 230 million ISK annually. However, while short waits may be acceptable, increasing frequencies for popular or overcrowded routes may also be of interest to riders, whose third most common comment in the survey free response was a desire for increased frequency of buses.

In our informal interviews and survey, the general sentiment expressed by riders was that when pulse scheduling works as intended it facilitates convenient transfers, but that increasing delays in Strætó’s system have resulted in buses often not being on time. Part of the frustration experienced by riders may be due to their expectations not being met rather than from the time they have to wait. People plan their schedules assuming they will be able to catch all of their transfers, and when buses become delayed it makes them late. One rider commented during an interview that he does not care what the bus schedule is as long as it is consistent.

Due to increases in schedule delays since the introduction of pulse scheduling to Strætó’s network, as well as rider feedback regarding long wait times between buses, pulse scheduling may no longer be the best strategy for Strætó. Strætó employees stated that it is often not possible for buses to make their connections due to traffic, and riders indicated that they are frustrated by the delays in the system. For these reasons, we recommend that Strætó work to remove pulse scheduling from their system across all times of day. Removing pulses will prevent the propagation of delays caused by buses waiting for each other at pulses, making the system timelier overall. In addition, the savings from eliminating waiting periods and layover costs from pulse routes can be used to help offset the costs of increasing bus frequency for popular or overcrowded routes. Furthermore, based on the results of our survey and informal interviews, we believe riders will not mind waiting short times for their connection as long as they are expecting to do so, meaning transfers will still be convenient for riders.

According to the results of our interviews and surveys, improved communications between Strætó and its users will increase rider satisfaction. For example, some riders mentioned that the schedules posted on the mobile app, website, and at stations were not always consistent. By ensuring that the information available to riders is clear and accurate, Straeto can enhance the rider experience.

While Strætó’s existing designated bus-only lanes allow buses to bypass traffic, they are too disconnected to be fully effective. By adding additional bus-only priority lanes and connecting more of the existing lanes together, delays and inconsistencies caused by heavy traffic can be mitigated. We acknowledge the expensive nature of this improvement but recommend ongoing consideration for designated lanes as larger city projects such as the proposed bus rapid transit system develop in the future.

Strætó is planning to add AFC systems to their buses in the future. The team encourages this decision for two main reasons: AFC will reduce passenger boarding delays by speeding up passenger payment and will generate additional data for analysis. Strætó has years’ worth of archived AVL data for every bus in the network. We learned from our interviews with Strætó’s data analyst that they do some evaluation, but typically focus on individual routes rather than the whole system. Analysis of AFC and AVL data will provide Strætó with a more complete picture of the end-to-end travel patterns of individual passenger which will be useful for future route planning.

The purpose of our research was to evaluate pulse scheduling in the overall context of Strætó’s route network. Our research showed that increasing schedule delays in the Capital Region have made pulse scheduling less feasible. As Reykjavík grows, Strætó will continue to play a major role in how people navigate the city. By reorganizing their network and schedules Strætó could increase convenience for riders, save money, and ultimately increase their ridership. An increase in ridership will improve mobility in the Capital Region and thus promote economic growth, social equality, and environmental friendliness. By taking steps toward implementing a more sustainable public transit system, Strætó will align itself more closely to the United Nations’ sustainability goals.