Niels van Oort

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

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

Unreliability of public transport is a well-known problem. During the design stages of public transport, little attention is paid to operational reliability, although many design choices have a great impact on schedule adherence. During the network design, reliability should be taken into account as a design parameter. This paper
deals with line length. A new design dilemma is introduced: length of line vs. reliability. Long lines offer many direct connections, thereby saving transfers. However, the variability is often negatively related to the length of a line, leading to less schedule adherence and additional waiting time for passengers. This paper suggests taking into account both the positive and negative effects of extending or connecting line . A tool is developed to calculate the additional waiting time due to variability and transfers based on actual journey and passenger data. A case study in The Hague shows that in the case of long lines with large variability, splitting the line could result in less additional travel time because of improved reliability. This benefit compensates for the additional transfer time, provided that the transfer point is well chosen. This research shows the effect of when the transfer point is chosen at stop with many and fewer passing travelers. The latter could lead to a decrease of about 30% in additional waiting time. Splitting a long line into two lines with an overlap in the central part could even result
in more time savings. In that case, fewer travelers have to transfer.

Read the full paper:Paper TRR 2009 Van Oort