Posted in 2013
Incorporating service reliability in public transport design and performance requirements
Public transport passengers consider service reliability a key quality aspect. However, in
most countries, actual services are not perceived as very reliable. To gain insights in how
public transport authorities deal with (improving) service reliability and planning, an
international survey was performed. This survey showed that there is little attention paid to
service reliability during the design of the network and the timetable. In addition, it illustrated that little consistency exists in approaches. In addition, a second survey in The Netherlands was performed, showing how public transport authorities deal with service reliability in relation to concession requirements and incentive regimes. The main findings are that consistency is lacking on this topic, even within the Netherlands, and that little attention is paid to passenger impacts of service reliability in concession requirements. This may result in services that do not match the (implicitly) required level of service reliability.
These surveys also demonstrated that there is no consistency in the definition of service reliability. We illustrated that this may lead to different levels of quality concerning these indicators, while actual quality is constant. In this paper, recommendations are presented to improve concession requirements as well as the design of network and timetable, both aiming at enhanced service reliability.
Read more: Thredbo 2013 paper Van Oort
Van voertuigpunctualiteit naar reizigersbetrouwbaarheid
Om een hoogwaardige OV exploitatie te bereiken, stellen overheden diverse eisen aan vervoerders met betrekking tot de exploitatie van het OV. Dat gebeurt zowel vooraf (bij aanbestedingen via bestekken) als tijdens de exploitatie (via concessie-eisen). Deze eisen zijn van grote invloed op het gedrag van de vervoerder voor wat betreft planning en bijsturing en daarmee op de kwaliteit op straat. Hoewel via de toolbox “Beter Bestek” van KpVV afgelopen jaren grote sprongen in kwaliteit en uniformiteit van OV-bestekken zijn gemaakt, geldt dit nog niet voor het aspect “op tijd rijden”. De aandacht is hiervoor weliswaar sterk toegenomen- de punctualiteit van NS is bijvoorbeeld een veelbesproken onderwerp- maar een uniforme aanpak en indicatoren ontbreken echter in Nederland.
In dit paper wordt onderzoek gepresenteerd dat inzicht biedt in de stand van zaken op dit moment voor wat betreft betrouwbaarheidseisen in bestekken (zowel in Nederland als in het buitenland). Hieruit blijkt dat er verschillende (suboptimale) aanpakken voorkomen. Op basis van de onderzoeken worden handvatten gepresenteerd om beter te kunnen sturen op een betrouwbaar OV, zowel bij aanbesteding als tijdens de exploitatie, met als resultaat beter OV op straat.
De belangrijkste aanbevelingen zijn om bij het vaststellen van eisen voor wat betreft het op tijd rijden een referentie- en gewenst kwaliteitsniveau vast te stellen, met daarbij een analyse wat haalbare verbeteringen zijn en wie daar invloed op heeft. Zo hebben OV autoriteit, gemeente en vervoerder elk hun rol en mogelijkheden. Opvallend is dat er momenteel weinig aandacht is voor de kwaliteit van de dienstregeling met betrekking tot punctualiteit, hoewel daar een sleutel voor succes ligt. Tot slot zijn de gebruikte indicatoren momenteel niet voldoende op de reiziger gericht, waardoor suboptimalisatie op de loer ligt. De veelgebruikte indicator punctualiteit houdt bijvoorbeeld niet direct rekening met fenomenen als te vroeg rijden, overstappen en regelmaat. In dit paper laten we rekenkundig zien wat de impact van verschillende, suboptimale indicatoren is.
Om tegemoet te komen aan beperkingen van huidige indicatoren wordt in dit paper een indicator gepresenteerd, extra reistijd per reiziger, die wel focus op de reizigerseffecten biedt en daarmee een beter ontwerp en uitvoering van OV faciliteert. Door in OV-bestekken te werken met goede indicatoren en ambitieuze, doch realistische eisen komt een beter OV snel dichter bij. Een beter OV begint immers met een beter bestek.
Optimizing Public Transport Planning and Operations Using Automatic Vehicle Location Data: The Dutch Example
There is a growing pressure on urban public transport companies and authorities to improve efficiency, stemming from reduced budgets, political expectations and competition between operators. In order to find inefficiencies, bottlenecks and potentials in the public transport service, it is useful to learn from recorded operational data. We first describe the state of publicly available transit data, with an emphasis on the Dutch situation. The value of insights from Automatic Vehicle Location data is demonstrated by examples. Finally, a software tool is described that makes quick comprehensive operational analysis possible for operators and public transport authorities, and was able to identify several bottlenecks when applied in practice.
Read more: Paper MT ITS Dresden Van Oort
The value of enhanced service reliability of public transport
Service reliability is an important quality characteristic in public transport. However,
in cost-benefit analyses (CBA), this quality aspect is rarely taken into account explicitly.
It is more common to calculate vehicle indicators (e.g. punctuality) instead of passenger
focused metrics. In this paper, we demonstrate how to calculate the passenger impacts of
service unreliability. In an actual case, the replacement of a bus line by a light rail line in Utrecht, we proved that our method is valuable and can be applied directly into practice. By calculating the benefits of the improved service reliability of the proposed light rail line, which were about 2/3 of all benefits, the cost benefit ratio was positive, which convinced the Dutch Minister of Infrastructure and Environment to support the project by €110 million.
Read the full paper: RailCopenhagen 2013 Value of service reliability paper Van Oort
The impact of scheduling on service reliability: trip-time determination and holding points in long-headway services
This paper presents research on optimizing service reliability of longheadway
services in urban public transport. Setting the driving time, and thus the
departure time at stops, is an important decision when optimizing reliability in urban
public transport. The choice of the percentile out of historical data determines the
probability of being late or early, while the scheduled departure time determines the
arrival pattern for travelers. A hypothetical line and a case study are used to determine
the optimal percentile value for long-headway services without and with holding
points. If no holding points are applied, it is shown that the 35-percentile value
minimizes the additional travel time to 25 % of the reference situation. In the case of
holding, two holding points combined with a 30–60-percentile value yield the best
performance: a further reduction of the additional travel time with 60 %.
Read the full paper: Paper Public Transport Van Oort 2012
Regularity analysis for optimizing urban transit network design
Transit network planners often propose network structures that either assume a certain level of regularity or are even especially focused on improving service reliability, such as networks in which parts of lines share a common route or the introduction of short-turn services. The key idea is that travelers on that route will have a more frequent transit service. The impact of such network designs on service regularity is rarely analyzed in a quantitative way. This paper presents a tool that can be used to assess the impact of network changes on the regularity on a transit route and on the level of transit demand. The tool can use actual data on the punctuality of the transit system. The application of such a tool is illustrated in two ways. A case study on introducing coordinated services shows that the use of such a tool leads to more realistic estimates than the traditional approach. Second, a set of graphs is developed which can be used for a quick scan when considering network changes. These graphs can be used to assess the effect of coordinating the schedules and of improving the punctuality.
Read the full paper: Public Transport Van Oort 2009
Reliability improvement in short headway transit services: Schedule-based and headway-based holding strategies
Improving service reliability is becoming a key focus for most public transport operators. One common operational strategy is holding. Holding vehicles can improve reliability, resulting in both shorter travel times and less crowding. In this paper, both schedule-based and headway-based holding strategies are analyzed in short headway services. Despite a significant focus on holding in current literature, some important aspects have not been researched previously. The main, new, variables are the maximum holding time, the reliability buffer time and, in the case of schedule-based holding, the percentile value used to design the schedule. Both a real line in The Hague (tram line 9) and hypothetical lines are analyzed with various levels of running time variability. Both headway-based and schedule-based holding have the largest effect if
deviations are high. When applying schedule-based holding and a maximum of 60 s. holding time is applied, the optimal value of the percentile value becomes about 65% for all lines analyzed. When no maximum holding time is applied, schedule-based holding is more effective, while there is no difference when the maximum holding time is set to 60s. This research also shows the effect of holding on crowding: An average level of irregularity of 20% could decrease to 15%, enabling either smaller capacity slack or less crowding.
Read the full paper: Paper TRR 2010 Van Oort
The impact of rail terminal design on transit service reliability
Ensuring reliable rail transit services is an important task for transit agencies. This paper describes research of the effects of various terminal configurations on reliability of services. Besides terminals, the results could also be used for short turning infrastructure. Short turning is a very widespread measure to restore service after major disturbances and in many rail networks, additional switches are constructed to enable short turning.
In this paper, it is suggested to consider reliability already during infrastructure design and the mechanisms and effects of infrastructure design are shown. Calculations of the average delay per vehicle, regarding three main types of terminals, show the effect of frequency on the one hand and occupancy time (determined by the distance from the switches to the platform (i.e. length of the terminal), technical turning time and scheduled layover time) on the other. The substantial effect of arrival variability and the number of lines using the terminal is illustrated as well. It is shown that using stochastic variables, delays will occur, although they are not to be expected in the static case. The best performance regarding reliability is achieved, when double crossovers are situated after the platforms. Single tailtracks facilitating the turning process are only acceptable if frequencies are low. Although, , they are often used in practice as short tuning facility for high frequent services. This research shows the large impact of occupancy time on expected delays. It is recommended to minimize this time by designing short distances between switches and platform and tailtracks. Capacity management is not common use in transit. However, increasing frequencies and large deviations force to consider limited capacity, while planning infrastructure. If not, delays will occur and additional measures are necessary to solve them. This could be more expensive in the long run.
Read the full paper: Paper TRR Van Oort 2010
Controlling operations of public transport to improve reliability: theory and practice
RandstadRail is a new light rail system between the cities of The Hague, Rotterdam and Zoetermeer in The Netherlands. During peak hours, the frequency on some trajectories is about 24 vehicles an hour. Dealing with these high frequencies and offering travelers a high-quality product, in terms of waiting times and the probability
of getting a seat, the operator designed a three-step controlling philosophy. The first step is to prevent deviations from occurring: the infrastructure is exclusively right of way as much as possible and at intersections RandstadRail gets priority over the other traffic. RandstadRail stops at every stop and never leaves before the
scheduled time. The second step in the philosophy is dealing with deviations by planning additional time in the schedule at stops, trajectories and terminals. Small deviations can be solved in this way. The final step to get vehicles back on schedule is performed by the traffic control centre: they have a total overview of all vehicles
and they can respond to disturbances like slowing down vehicles nearby a delayed vehicle. Experiencing major disturbances rerouting and shortening of lines is possible. RandstadRail has been in operation since 2007. The actual data of the performance is used to analyze the actual effects of the control philosophy. It is shown that due to the applied measures the variability of the driving times is reduced, whereas punctuality has increased. This leads to a higher level of service, creating shorter travel times and a better distribution of passengers across the vehicles.
Read the full paper:Paper TRR 2009 Van Oort