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Timetable stability depends on the regularity of trains. Any deviation from the planned timetable leads to its instability. Railway network characteristics determine the capacities of the transport service. Depending on the capacity calculation method, time components are added to the minimum headway to ensure timetable stability. The UIC 405 method is simple and can be used on all railways. The disadvantage is that the calculations are based on average data. According to the method, the minimum headway consists of the time of the average headway interval, additional time and the buffer time. The additional time is precisely defined by the number of APB sections, while the buffer time is in the average value. When creating the timetable, the goal is optimal utilisation of the infrastructure. If the headway is too long, the capacity is not used, and if it is too short, timetable instability will ensue. Instead of averaging, this work calculates a buffer time that depends on the ratio of the travel time of the previous and the following trains. In this way, the headway is optimised and the calculation of the UIC 405 method is improved.

A reasonable calculation of railway capacity is very important for research. With the rapid development of high-speed railways, more and more differences between traditional and modern railways have emerged in the transportation organization and capacity calculation methods. In this article, the calculation methods used under different conditions with different train types are studied based on the train deduction method. Train deduction is a method that calculates the number of trains that cannot pass through the line when other trains change their stop plan or operation speed based on the coefficient of deduction method, which is widely used in China. Then, optimized models for trains with the same-speed and different-speeds are built to determine the maximum number of trains. These models are built based on the constraints of passenger service quality and overtaking times. In addition, the models are solved based on a train operation plan. Hence, the capacity calculated by these methods is more reasonable for the actual condition. Finally, an actual case of Beijing–Shanghai high-speed railway is implemented and tested with the model. The optimal capacity scheme is simulated and analysed, and the result agreed well with the railway transport enterprise. First published online 5 February 2024

The automotive industry is a highly competitive sector. Manufacturers must effectively control highly complex production processes in order to fulfil all customer orders for customized cars on time, on budget and to the required quality. In this paper, the authors focus on improving the flow time of asynchronous automotive assembly lines by reducing the buffer time. A simulation-search heuristic procedure was developed and confirmed in a 5 workstations asynchronous assembly line installed in an automotive company. The proposed procedure identifies optimal performing buffer profiles for each storage level which guarantees lowest flow time while keeping the same throughput level. Experiments results show that our new algorithm significantly outperforms existing results, especially for large scale problems. [ABSTRACT FROM AUTHOR]

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This paper evaluates the effectiveness of toll roads in reducing congestion and improving travel time reliability on streets within its vicinity, over time. The data, from the year 2013 to 2017, for the Triangle Expressway in the city of Raleigh, North Carolina was used in the systemic evaluation process. The spatial and temporal variations in the travel time distributions on the toll road, parallel route, and near-vicinity cross-streets (in a 2-mile buffer) were evaluated. The average travel time (ATT), the 95th percentile travel time (or planning time, PT), the buffer time (BT), and the buffer time index (BTI) were computed for each link by the day-of-the-week and the time-of-the-day. Though there was an improvement in travel time after the speed limit change in the year 2014, the travel time reliability got reduced on the Triangle Expressway. Over time, there was a gradual improvement in BT and BTI. The parallel route reliability decreased significantly over time, whereas the travel time reliability of cross-streets showed a consistent trend. The stabilization of travel time distributions and the reliability measures in the year 2017 indicate that further reduction in performance measures may not be expected in the next few years on the near-vicinity links.

This paper evaluates the effectiveness of toll roads in reducing congestion and improving travel time reliability on streets within its vicinity, over time. The data, from the year 2013 to 2017, for the Triangle Expressway in the city of Raleigh, North Carolina was used in the systemic evaluation process. The spatial and temporal variations in the travel time distributions on the toll road, parallel route, and near-vicinity cross-streets (in a 2-mile buffer) were evaluated. The average travel time (ATT), the 95th percentile travel time (or planning time, PT), the buffer time (BT), and the buffer time index (BTI) were computed for each link by the day-of-the-week and the time-of-the-day. Though there was an improvement in travel time after the speed limit change in the year 2014, the travel time reliability got reduced on the Triangle Expressway. Over time, there was a gradual improvement in BT and BTI. The parallel route reliability decreased significantly over time, whereas the travel time reliability of cross-streets showed a consistent trend. The stabilization of travel time distributions and the reliability measures in the year 2017 indicate that further reduction in performance measures may not be expected in the next few years on the near-vicinity links. [ABSTRACT FROM AUTHOR]

The focus of this paper is to identify thresholds and monetize travel time reliability to evaluate transportation projects/altematives. Stated preference survey was designed to capture perceptions of North Carolina motorists. A random survey was carried out across the cities and towns in North Carolina, and 334 valid responses were gathered from the participants. The results indicate that 60.8% of the random survey participants were willing to take an unreliable route with travel time varying from 20 to 30 minutes, whereas the remaining 39.2% of the random survey participants prefer a reliable 25-minute route. As the variation in travel time increased on the unreliable route, random survey participants preferred to opt for a reliable route over an unreliable route. Four days of unreliability per month was acceptable for only 33.8% of the random survey participants. They shifted from an unreliable route to a reliable route with an increase in the number of unreliable days in a month. Overall, the generalized value of buffer time from the random survey is estimated equal to $0.45 per minute. Differences in the value of buffer time were observed between cities, towns, and other areas across North Carolina. While a higher percentage of focus group survey participants preferred the reliable route, the value of buffer time based on data collected through focus group survey is also comparable to the random survey-based value. [ABSTRACT FROM AUTHOR]

Recovery time in the rail industry is the additional time that is included in train timetables over and above the minimum journey time necessary often with the explicit aim of improving punctuality. Recovery time is widely used in railways in a number of countries but prior to this study there has been no investigation of the rail users' point of view. Perceived recovery time, such as being held outside stations and prolonged stops at stations, might have some premium valuation due to the frustration caused. If perceived recovery time in train timetables does carry a premium, then the benefits of improved punctuality achieved by it will be reduced. This paper is the first to investigate passengers' views and preferences on the use of recovery time. We summarise the findings of a large study and provide estimates of passengers' valuations of recovery time, both relative to in-vehicle time and late time, that can be used for economic appraisal purposes. Overall, we find most passengers support the use of recovery time but the context is important. Only 13% of users disapprove of its use as a tool to reduce lateness. The estimated premia vary by demand characteristics and are significant in some contexts, although on average are of a small magnitude. The applicability of the estimates is demonstrated through the appraisal of an actual scheme in the UK. We observe that the introduction of more recovery time along with the subsequent improvement in reliability can lead to significant reductions in generalised journey time, even when recovery time carries a valuation premium. We must however strike a word of caution since we note that there were higher than expected proportions of non-traders in the survey which may have affected the results; future studies into the topic should look to minimise the proportion of non-traders. This study provides valuable and necessary first steps in this challenging topic. [ABSTRACT FROM AUTHOR]

This research is carried out to evaluate the efficacy of toll roads in reducing travel time and improving travel time reliability on links within its vicinity, using data for the Triangle Expressway in Raleigh, North Carolina, United States. Various travel time reliability measures were computed for each link, referred to as Traffic Message Channel (TMC), by day-of-the-week and time-of-the-day. The travel time reliability of the links adjacent to the toll roads (both the parallel route and the cross streets) before construction, during phase 1 operation, during phase 2 operation, and after opening the toll road for complete service was examined. The statistical tests reveal a notable improvement in travel time reliability measures within the vicinity of the toll road after opening the toll road for complete service. The methodology and study results help transportation planners and engineers in comparing the performance or efficiency of toll roads/managed lane facilities in terms of travel time reliability and enhancing the sustainability of the transportation system. [ABSTRACT FROM AUTHOR]

A travel time reliability-based approach is proposed to assess the effect of the light rail transit (LRT) system on the road network within its vicinity. A 4-mile stretch of the Blue Line LRT extension, which connects the Old Concord Road and the University of North Carolina at Charlotte (UNC Charlotte) main campus in Charlotte, North Carolina (NC), was considered as the study corridor. The raw travel time data was collected from the Regional Integrated Transportation Information System (RITIS) website at one-minute intervals. The average travel time (ATT), planning time (PT), buffer time (BT), buffer time index (BTI), and planning time index (PTI) were computed for each link, referred to as Traffic Message Channel (TMC) in this research, by day-of-the-week and time-of-the day. Further, the travel time reliability of the links on the LRT extension corridor and adjacent corridors (both the parallel route and the cross-streets) were computed for different scenarios: network without LRT, testing phase of LRT, first month of LRT operation, third month of LRT operation, sixth month of LRT operation, and ninth month of LRT operation. The travel time reliability of the alternate route and cross-streets was affected by the LRT system operation. Increased green times and better coordination on the LRT corridor and the benefits associated with the alternate mode/route choice for commuters may be the reason behind the steadiness in travel time performance measures due to the LRT. The methodology and findings help transportation planners and engineers in comparing the performance or efficiency of large-scale public transportation projects like LRT and bus rapid transit (BRT) on travel time reliability within its vicinity. [ABSTRACT FROM AUTHOR]

Traffic congestion is one of the most notorious troubles, one that undermines social costs in urbanized areas in the world. Because of the congestion problem, drivers are trying to find the shortest and most reliable paths. Regarding the reliability of travel time, there already exist a few measures, such as Standard Deviation, Buffer Time, and Buffer Index. However, they have fundamental limitations in calculation or in application. Therefore, we tried to apply the Gini Coefficient, which is a well-known measure of statistical dispersion, which describes the inequality of income or wealth distribution among a nation's residents, as a new measure for evaluating travel time reliability. In order to verify the new measure, we calculated Gini coefficients of five different expressway sections on AADT day and Chuseok and reviewed the potential advantage of the alternative by comparing the result with those from existing measures. In the analysis, the new measure showed us reasonable and reliable results and proved its applicability of appraising travel time reliability. [ABSTRACT FROM AUTHOR]

Train movements are subject to disturbances and disruptions, which may cause late departures and/or late arrivals at particular locations (e.g., terminals, stations, crossings) with respect to their pre-determined times. To prevent possible deviations from the scheduled times, time allowances are added to the process times (i.e., running times) as time supplements and to the time interval between successive trains (i.e., minimum headway) as buffer times. The amount of time allowances is decided during the timetable planning process and their contribution to the service quality is monitored in actual operation. The adequacy of time allowances results in punctual train operations, which is one of the primary interests of service users and providers. Because the sequence of train departure and arrival times can be viewed as a stochastic process, the performance of train operations may be analyzed and modeled using Markov chains. We modeled train departure and arrival delays at stations as states and analyzed the successive state changes along train paths in a single track railway. This allowed us to predict train states at certain event time steps and to estimate steady-state delay probabilities. The former may be used to reschedule train movements and the latter to measure timetable robustness. [ABSTRACT FROM AUTHOR]

Schedule padding is a frequent strategy applied by transport providers, often used to improve their on-time performance. Normally, time efficiency is evaluated in terms of arrival delays. However, in the air transport industry, evidence shows that flights tend to depart late, although arriving on time. This study investigates the carriers' turnaround time strategy by comparing the scheduled and actual daily movements of all flights from or to Europe in 2019. Results show that turnaround variations are more frequent in larger airports, during peak hours, and when an aircraft performs a higher number of flights. Low-cost carriers usually set a significantly shorter turnaround time than traditional carriers, using a larger part of the scheduled block time for ground operations. This strategy greatly influences on-time performance measures and other efficiency indicators traditionally based on scheduled activities, with important implications for both airlines and passengers. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of two time-based payment contracts in an assembly system that consists of one assembler and two suppliers, in which both suppliers' production times are stochastic. The assembler initially chooses the contract type (delay payment contract vs on-time payment contract) and the buffer time, and two suppliers have to simultaneously determine their production lead times. We find that in equilibrium, both suppliers cut down their production lead times under the delay payment contract, and this makes them worse off than that under the on-time payment contract. Differently, the delay payment contract is the assembler's dominant option. This is because by setting the buffer time, the assembler can significantly mitigate the possible delay risk caused by the suppliers' decentralization under the delay payment contract. It also shows that the entire supply chain achieves the same service level under either the centralized condition or the decentralized condition, regardless of the applied payment contract type. Note that these results are robustness when we extend the model into the system containing N ( N $$>$$ 2) independent suppliers. [ABSTRACT FROM AUTHOR]

Many factors affect the performance of temporary schedule adjustments following incidents. These factors include static recovery scheduling, stochastic flight delays and ‘real-time’ schedule adjustments. Most research on recovery scheduling has focused on improving static recovery scheduling models. None has analyzed these factors from a systems perspective. The research on which this paper is based proposes a framework, embodying a simulation process, that is not only be able to analyze the influence of stochastic flight delays on static recovery scheduling, but can also help to design more effective flexible buffer times and ‘real-time’ schedule adjustment rules. To test the framework we perform a simulation using data from a Taiwan domestic airline. The preliminary results show that the framework could be usefully applied by airlines in practice. [ABSTRACT FROM AUTHOR]

There are many factors that affect gate assignments in an airport''s operations. These factors include static gate assignments, stochastic flight delays and real-time gate assignments. Most research on gate assignments in the past has laid stress on improving the performance of static gate assignments. None has analyzed the interrelationship between static gate assignments and real-time gate assignments as affected by the stochastic flight delays that occur in real operations. In addition, none has designed flexible buffer times for static gate assignments to effectively absorb stochastic delays in real-time gate assignments. This research proposes a simulation framework, that is not only able to analyze the effects of stochastic flight delays on static gate assignments, but can also evaluate flexible buffer times and real-time gate assignment rules. Finally, a simulation based on Chiang Kai-Shek airport operations is performed to evaluate the simulation framework. [Copyright &y& Elsevier]

Delay propagation is the flight departure delay caused by the arrival delay of pre-segment flight. Chinese airline market has suffered very poor on-time performance (OTP) in recent years. It is, however, unclear whether delay propagation prevails as one major source for such problem. This study first aims to empirically quantify delay propagation in the Chinese airline market. Specifically, we shed light on heterogenous levels of delay propagations across different airports and airlines. Then, the distinct delay propagation patterns in China are also discussed and compared with other developed airline markets (e.g., the US and Europe). Our estimation is based on OTP data for over 12 million Chinese flights covering the 2015–2017 period. Specifically, it is found that 10 min arrival delay of pre-segment flight within 1 hr before the departure lead to an average of 7.49 mins delay propagation for subsequent departure flight. Arrival delay of earlier pre-segments (1–2 and 2–3 hr before the departure) leads to much less delay propagation, due to longer ground buffer. Chinese airlines arrange longer ground and flight buffer than that of the US airlines to prevent the delay propagation from accumulating along the subsequent flights in a day. Thus, unlike the US market, delay propagation is not the major reason for poor OTP in China. In addition, delay propagation is less prevailing at the Chinese hub airport. This is because China has relied on point-to-point network, which does not require sophisticated schedule coordination. And the local passengers at these Chinese hub airports have higher time value such that the Chinese airlines also try to improve OTP at these hub airports to better serve these lucrative but time-sensitive local passengers. Unlike the European LCCs, Spring Airlines, the largest low-cost carrier (LCC) in China, outperforms major full-service carriers (FSCs) in controlling delay propagation. This finding may also apply to other Northeast Asian LCCs sharing common operational characteristics as Spring Airlines. Last, we find that airlines purposely tolerate moderate departure delays of up to 15 min, which is the threshold that defines delays, no matter whether the pre-segment flight arrives late or on-time. The relevant policy and managerial implications are also discussed. • We estimate delay propagation in the Chinese airline market over the 2015–2017 period. • Our empirical evidence suggests that delay propagation seems not the major source for China's poor OTP. • The Chinese hub airports have lower level of delay propagation than the non-hub airports. • Unlike the European LCCs, Chinese LCCs outperform FSCs in controlling delay propagation. • Defining on-time departure or arrival with delay less than 15 min discourages airlines to shorten turnaround time. [ABSTRACT FROM AUTHOR]