Differential Travel Times Research Articles

Uppermost Mantle Seismic Pn‐Velocity in Continental China and Its Tectonic Implications

AbstractWe construct a high‐resolution Pn‐velocity model in continental China through a new tomographic scheme simultaneously inverting event epicenter location and Pn‐velocity and accurately accounting for the Pn propagation effects of irregular crustal thickness variation. The inversion integrates a combined data set of 32,427 absolute Pn travel times and 62,431 interstation Pn differential travel times manually picked from the recordings of 2,989 stations in and around continental China, yielding a model of spatial resolutions ranging from 0.75° × 0.75°–3° × 3°. Major Pn‐velocity features revealed by the model and the tectonic processes we attribute to include: (a) high Pn‐velocities beneath major cratonic blocks and the southern Tibetan Plateau attributed to low temperatures of cratons, (b) low Pn‐velocities beneath the eastern North China craton around the Tan‐Lu fault and the central South China block attributed to high temperatures and low‐Mg# () peridotites in response to the Mesozoic‐Cenozoic subduction of the Pacific plate, and beneath the Trans‐North China orogen, most regions of the Tibetan blocks and the central Tianshan orogen attributed to high temperatures after multiple tectono‐thermal events in response to the Mesozoic‐Cenozoic subduction of the Pacific plate, the Triassic convergence of the North China, Yangtze, and northern Tibetan blocks and the Cenozoic India‐Eurasia collision, and (c) intermediate Pn‐velocities beneath the marginal regions of the Ordos block and Micang‐Daba region attributed to possible extrusion of hot asthenospheric flow from the Tibetan Plateau in response to far‐field effects of the India‐Eurasia collision.

Tackling the challenges of tectonic tremor localization using differential traveltimes and Bayesian inversion

SUMMARY Episodic tremor and slip events in Northern Cascadia produce low-frequency, emergent seismic signals, often referred to as tectonic tremor. Methods designed to locate tremor face two challenges that increase the likelihood of producing low quality catalogues: first, signal arrival and duration are often poorly defined; second, high rates of tremor activity during episodes can cause multiple signals to be indiscernible from each other. In this paper, we present a new method of locating tectonic tremor using differential traveltimes from a waveform-envelope cross-correlation in a grid-based Bayesian inversion. To address the aforementioned challenges, we use a recently developed three-dimensional shear wave velocity model to compute traveltimes, and include processes to remove data outliers, estimate data error statistics, and quantify uncertainties within the Bayesian framework. Although this method is designed for tremor, to test the approach we consider a set of 58 local earthquakes between magnitudes −0.07 and 2.6 in the Southern Vancouver Island region and obtain well-constrained relocations. Residuals between official catalogue values and our relocations are quantized with respect to the 1 km grid resolution of the inversion, and average 2.7 km in epicentre and 5.2 km in depth. Analysis shows that depths of relocations are sensitive to horizontal variations and simplifications in velocity models. We then present our catalogue of tremor events during the 2004 episodic tremor and slip event beneath Southern Vancouver Island, Canada. Median uncertainties of tremor events quantified by 95 per cent credibility interval widths in a 1 km grid are 5 km and 9.km in horizontal and depth directions, respectively (1.2 km and 2.3 km using traditional standard deviation-based uncertainties). Comparison of our catalogue with previously published work demonstrates that our new method yields a good detection rate, a greater degree of epicentral clustering, and better depth resolution of tremor events. Catalogues produced using this new method may help to provide insight into the spatial extent of tremor, especially in depth, by yielding enhanced constraints on source locations on a regional scale.

A Tiny-Fault Detection Strategy Based on Phase Congruency—An Example of Carbonate Reservoir in Ordos Basin, China

Tiny-fault detection plays a very important role in the research on the tight oil and gas reservoir in well area X in Ordos Basin, China. In this study, the target formation is the Majiagou dolomite reservoir section under the Ordovician salt with low-amplitude structures generally developed. The conventional attributes extracted from migrated seismic data could not achieve ideal results in detecting hidden faults with small displacement due to slight travel time differences and weak amplitude disturbances. To address this challenge, a segment and fusion strategy was adopted to highlight tiny faults in this region. First, the phase congruency analysis method was used to extract the local edges of coherence to locate the faults. Second, in the extraction process, the coherence was divided into segments according to the fault scales, and then enhanced segment by segment and fused. Third, the empirical formula of the new fault indicator was constructed by the phase congruency features, which can be used to accurately characterize tiny faults. This strategy performs well in both model tests and the migrated seismic data.

Up-to-fivefold reverberating waves through the Earth’s center and distinctly anisotropic innermost inner core

Probing the Earth’s center is critical for understanding planetary formation and evolution. However, geophysical inferences have been challenging due to the lack of seismological probes sensitive to the Earth’s center. Here, by stacking waveforms recorded by a growing number of global seismic stations, we observe up-to-fivefold reverberating waves from selected earthquakes along the Earth’s diameter. Differential travel times of these exotic arrival pairs, hitherto unreported in seismological literature, complement and improve currently available information. The inferred transversely isotropic inner-core model contains a ~650-km thick innermost ball with P-wave speeds ~4% slower at ~50° from the Earth’s rotation axis. In contrast, the inner core’s outer shell displays much weaker anisotropy with the slowest direction in the equatorial plane. Our findings strengthen the evidence for an anisotropically-distinctive innermost inner core and its transition to a weakly anisotropic outer shell, which could be a fossilized record of a significant global event from the past.

Examining inequality in the time cost of waiting.

Time spent waiting for services represents unproductive time lost while fulfilling needs. We use time diary data from the nationally representative American Time Use Survey to estimate the difference between high- and low-income people in time spent waiting for basic services. Relative to high-income people, low-income people are one percentage point more likely to wait on an average day, are three percentage points more likely to wait when using services, spend an additional minute waiting for services on a typical day and spend 12 more minutes waiting when waiting occurs. The unconditional gap in waiting time suggests low-income people spend at least six more hours per year waiting for services than high-income people. The income gap in waiting time cannot be explained by differences in family obligations, demographics, education, work time or travel time. Further, high-income Black people experience the same higher average wait times as low-income people regardless of race.

Acesulfame allows the tracing of multiple sources of wastewater and riverbank filtration

Aquifers providing drinking water are increasingly threatened by emerging contaminants due to wastewater inputs from multiple sources. These inputs have to be identified, differentiated, and characterized to allow an accurate risk assessment and thus ensure the safety of drinking water through appropriate management. We hypothesize, that in climates with seasonal temperature variations, the sweetener acesulfame potassium (ACE) provides new pathways to study wastewater inputs to aquifers. Specifically, this study investigates the temperature-driven seasonal oscillation of ACE to assess multiple sources of wastewater inputs at a riverbank filtration site. ACE concentrations in the river water varied from 0.2 to 1 μg L−1 in the cold season (T < 10 °C) to 0–0.1 μg L−1 in the warm season (T > 10 °C), due to temperature-dependent biodegradation during wastewater treatment. This oscillating signal could be traced throughout the aquifer over distances up to 3250 m from two different infiltration sources. A transient numerical model of groundwater flow and ACE transport was calibrated over hydraulic heads and ACE concentrations, allowing the accurate calculation of mixing ratios, travel times, and flow-path directions for each of the two infiltration sources. The calculated travel time from the distant infiltration source was of 67 days, while that from the near source was of 20 days. The difference in travel times leads to different potential degradation of contaminants flowing into the aquifer from the river, thus demonstrating the importance of individually assessing the locations of riverbank infiltration. The calibrated ACE transport model allowed calculating transient mixing ratios, which confirmed the impact of river stage and groundwater levels on the mixing ratio of the original groundwater and the bank filtrate. Therefore, continuous monitoring of ACE concentrations can help to optimize the management of the water works with the aim to avoid collection of water with very short travel times, which has important regulative aspects. Our findings demonstrate the suitability of ACE as a transient tracer for identifying multiple sources of wastewater, including riverbank filtration sites affected by wastewater treatment plant effluents. ACE seasonal oscillation tracking thus provides a new tool to be used in climates with pronounced seasonal temperature variations to assess the origins of contamination in aquifers, with time and cost advantages over multi-tracer approaches.

Double‐Difference Adjoint Tomography of the Crust and Uppermost Mantle Beneath Alaska

AbstractWe perform adjoint waveform tomography to reveal the P‐wave velocity structure of the crust and uppermost mantle in Alaska by using common‐source double‐difference traveltime data. Our underlying forward modeling tool is a 3D seismic‐wave solver called SPECFEM3D_GLOBE. We select ∼13,000 high‐quality P‐wave arrivals from 147 earthquakes recorded by more than 600 stations. The waveforms are filtered between 15 and 8 s and used to generate about 100,000 differential traveltimes via the cross‐correlation technique. We invert these common‐source differential traveltimes for a P‐wave velocity model down to 150 km depth in Alaska. In the upper mantle, a high‐velocity zone is imaged along the Aleutian volcanic arc, which represents the Pacific plate subducting beneath the North America plate. On the eastern edge of the subducting Pacific plate, the imaged high‐velocity anomaly extends distinctly beyond the Wadati–Benioff zone, indicating an aseismic slab edge. We observe an absence of a low‐velocity mantle wedge beneath the Denali Volcanic Gap (DVG) in our tomographic model. This finding suggests that minimal melt accumulation exists beneath the DVG, which may explain the cessation of magmatism there. Our model also reveals a high‐velocity anomaly near the Wrangell Volcanic Field (WVF), suggesting the possible existence of the Wrangell slab or the high‐velocity slab edge of the Yakutat slab. A potential slab gap shown as a low‐velocity body is detected at 95–125 km depth near the WVF, which could act as a channel to transport mantle materials to feed the cluster of volcanoes in the WVF.

Effect of Optimization Time-Scale on Learning-Based Cooperative Merging Control at a Nonsignalized Intersection

Automated driving and the widespread use of large-scale communication infrastructure are expected to facilitate highly cooperative driving. Although considerable research has focused on developing efficient cooperative control methods for nonsignalized intersections, the effect of cooperative control for conflicting target vehicles on future traffic flow is yet to be investigated. Therefore, we aim to investigate whether the impact of such cooperative control on future traffic should be considered. We established a traffic simulator and several machine-learning methods to select the optimal cooperative method. The decision tree and deep neural network were trained on two indices that evaluate short-term/long-term predictive control: to minimize the travel time of the (1) conflicting vehicles and (2) all vehicles including future traffic flow. Simulation analysis results indicated that there were no significant differences in the total travel times between these indices. This finding indicates that efficient traffic flow, which includes future traffic flow, is achievable by short-term cooperative control methods that can be established easily.

A comparative analysis of public transport accessibility to hospitals in Córdoba (2019–2023): Where are we now?

Abstract The coronavirus disease-2019 (COVID-19) pandemic and the mobility restrictions governments imposed to prevent its spread changed the cities’ ways of living. Transport systems suffered the consequences of the falling travel demand, and readjustments were made in many cities to prevent the complete shutdown of services. In Córdoba, the second largest city in Argentina, the Municipality dictated route cuts and reduced frequencies to sustain the buses and trolleys system. In 2022, Martinazzo and Falavigna assessed potential accessibility to hospitals before (2019) and during the pandemic (2021). Overall, the study indicated that average travel times increased by 20% and that the gap between less vulnerable and more vulnerable population quintiles reached almost 8 points. In this paper, potential accessibility to public hospitals in 2022 and 2023 is calculated using Martinazzo and Falavigna’s (2022) work as a baseline to compare, considering that neither cutting the services during the pandemic nor recovering the service after the pandemic the Municipality performed an accessibility assessment. The main results showed that, despite the system having almost recovered its extension by 2023, it maintained the regressive tendency between less vulnerable and more vulnerable population quintiles, as the difference in average travel time between these two groups reached up to 14 min, while the cumulative opportunities measure for the high-income groups was up to 68% higher than the most vulnerable households.

Inversion of Deep-Water Velocity Using the Munk Formula and the Seabed Reflection Traveltime: An Inversion Scheme That Takes the Complex Seabed Topography Into Account

The sound speed of seawater is not constant. It varies with season, day time, depth and range. This variation was not considered in marine seismic data processing and imaging before deep-water seismic acquisition became a routine activity. As a result, non-ignorable errors may be contained in the final migrated-image of deep-water seismic data. To eliminate such errors, we propose here a scheme for inverting the seawater velocity under the condition that the seabed has a complex topography. In this scheme, the seabed topography is represented by step grids constrained by measured water depth data, and the sound profile is assumed to be the one satisfying the Munk formula. Thus, only the parameters appearing in the Munk formula need to be inverted. This is quite different from the conventional inversion schemes that take the velocity as the inversion target. We use the conjugate gradient method to minimize the objective function given as the sum of squares of traveltime differences. Tests on synthetic common-shot data set show that our scheme presented here works as expected. Applications to real marine data set further validates the reasonability and feasibility of our scheme under complex seabed topography. To investigate the reliability of our inversion scheme, we migrate the real 2D data set using the Kirchhoff migration with the inverted Munk profile as the velocity model. The corresponding results show that the seawater velocity obtained by our inversion scheme improves the imaging quality of underwater structures.

Assessing travel time-based accessibility to outdoor ice skating fields for children in Helsinki during the COVID-19 pandemic

Informal sport is central to Finnish children’s leisure and physical activity time. This paper aims to build a better understanding of the travel time-based accessibility to informal sports facilities, specifically to ice skating fields, for children and adolescents (aged 7–19) in the city of Helsinki. We focused on the winter of 2020–2021 because COVID-19 restrictions on indoor activities resulted in ice skating fields being among the few public facilities that could remain open. Additionally, the weather was favourable for maintaining outdoor ice skating fields. We analysed if there would be a difference in children’s independent travel times by public transport or walking to ice skating fields due to the COVID-19 pandemic related recommendations by Helsinki Region Transport to avoid public transport. Children in Finland usually travel to and from school independently. Hence we focused on the transition from public transport to walking and omitted car usage, which would require an adult. We also looked at the potential differences in travel time to ice skating fields by analysing different types of fields separately. This difference would be of significance if climate change resulted in warmer winters in Finland. Helsinki has two types of ice skating fields: naturally frozen and mechanically frozen, of which only the mechanically frozen fields would be used during a warmer winter that is above zero degrees Celsius. We took a geographic information systems (GIS) analysis approach using travel time and population catchments. The study’s main findings show that during a milder winter and by walking, the accessibility for children is greatly reduced to 55.2%; that is, children face an increased travel time when naturally frozen ice skating fields are not in use. However, almost 100% of the child population can access both types of fields within a travel time of 30 minutes by public transport.

The development of audio–visual temporal precision precedes its rapid recalibration

Through development, multisensory systems reach a balance between stability and flexibility: the systems integrate optimally cross-modal signals from the same events, while remaining adaptive to environmental changes. Is continuous intersensory recalibration required to shape optimal integration mechanisms, or does multisensory integration develop prior to recalibration? Here, we examined the development of multisensory integration and rapid recalibration in the temporal domain by re-analyzing published datasets for audio–visual, audio–tactile, and visual–tactile combinations. Results showed that children reach an adult level of precision in audio–visual simultaneity perception and show the first sign of rapid recalibration at 9 years of age. In contrast, there was very weak rapid recalibration for other cross-modal combinations at all ages, even when adult levels of temporal precision had developed. Thus, the development of audio–visual rapid recalibration appears to require the maturation of temporal precision. It may serve to accommodate distance-dependent travel time differences between light and sound.

On the measurement ofSdiff splitting caused by lowermost mantle anisotropy

SUMMARYSeismic anisotropy has been detected at many depths of the Earth, including its upper layers, the lowermost mantle and the inner core. While upper mantle seismic anisotropy is relatively straightforward to resolve, lowermost mantle anisotropy has proven to be more complicated to measure. Due to their long, horizontal ray paths along the core–mantle boundary (CMB), S waves diffracted along the CMB (Sdiff) are potentially strongly influenced by lowermost mantle anisotropy. Sdiff waves can be recorded over a large epicentral distance range and thus sample the lowermost mantle everywhere around the globe. Sdiff therefore represents a promising phase for studying lowermost mantle anisotropy; however, previous studies have pointed out some difficulties with the interpretation of differential SHdiff–SVdiff traveltimes in terms of seismic anisotropy. Here, we provide a new, comprehensive assessment of the usability of Sdiff waves to infer lowermost mantle anisotropy. Using both axisymmetric and fully 3-D global wavefield simulations, we show that there are cases in which Sdiff can reliably detect and characterize deep mantle anisotropy when measuring traditional splitting parameters (as opposed to differential traveltimes). First, we analyze isotropic effects on Sdiff polarizations, including the influence of realistic velocity structure (such as 3-D velocity heterogeneity and ultra-low velocity zones), the character of the lowermost mantle velocity gradient, mantle attenuation structure, and Earth’s Coriolis force. Secondly, we evaluate effects of seismic anisotropy in both the upper and the lowermost mantle on SHdiff waves. In particular, we investigate how SHdiff waves are split by seismic anisotropy in the upper mantle near the source and how this anisotropic signature propagates to the receiver for a variety of lowermost mantle models. We demonstrate that, in particular and predictable cases, anisotropy leads to Sdiff splitting that can be clearly distinguished from other waveform effects. These results enable us to lay out a strategy for the analysis of Sdiff splitting due to anisotropy at the base of the mantle, which includes steps to help avoid potential pitfalls, with attention paid to the initial polarization of Sdiff and the influence of source-side anisotropy. We demonstrate our Sdiff splitting method using three earthquakes that occurred beneath the Celebes Sea, measured at many transportable array stations at a suitable epicentral distance. We resolve consistent and well-constrained Sdiff splitting parameters due to lowermost mantle anisotropy beneath the northeastern Pacific Ocean.

Optical coherence tomography – basic optical principles

AbstractOptical Coherence Tomography (OCT) is an optical analogue to ultrasound imaging. The much higher speed of light compared with sound allows for finer cross‐sectional views of the retina and anterior segment. Since it is extremely difficult to directly detect the shorter “echo” times it takes light to travel from different structures at axial distances within the eye, interferometry is used. Incident light is thus split into two beams, and the beam backscattered from the ocular tissue is then compared (“interfered”) with the beam that has travelled a known time from the reference mirror. Broadband (i.e., low “coherence”) light sources are used, because they produce a wider band of wavelengths, and thereby enable greater sensitivity in comparing the travel time differences of the two beams. In time‐domain OCT, the reference mirror position is altered, so that interference patterns are generated whenever the two beams have travelled almost the same amount of time. In spectral‐domain OCT, the reference mirror position is fixed and the mixed interference patterns are separated via spectral wavelength analysis. This lecture will explain underlying concepts of OCT with a discussion of cutting‐edge technological developments.

The origin of groundwater salinity in the Matanza-Riachuelo aquifer system, Argentina

Groundwater salinization is a severe worldwide issue affecting many coastal aquifers by threatening their freshwater resources (Werner et al., 2013; Michael et al., 2017). The Matanza-Riachuelo River Basin (MRRB) is a coastal-continental basin that supplies fresh water to the Greater Buenos Aires conurbation, encompassing approximately 10% of Argentina's population. Among other environmental degradation issues, salinization is one of the most important processes affecting the MRRB. In this study, salinization across the MRRB was unraveled using major (Cl, HCO3, SO4, Na, Ca, Mg) and tracer (Br) solutes, together with stable (18O, 2H, 13C) and radioactive isotopes (3H, 14C). Three different saline end-members were identified: Upper Basin Slightly Saline (UBSS), Lower Basin Highly Saline (LBHS), and Lower Basin Hyper Saline (LBHPS). The salinity of the UBSS and the LBHPS end-members was associated with the Miocene Paraná Formation connate marine water, while the salinity of the LBHS end-member were associated with the Pleistocene to Holocene Postpampeano Sediments connate seawater. The estimated 14C values were related to travel time differences in the flow paths delivering water to different zones of the Puelche Aquifer. Groundwater in the upper basin sector of the Puelche Aquifer was likely to belong to long, regional groundwater flow recharged outside the MRRB boundary. Groundwater in the top of the Puelche Aquifer at the lower basin comes from the Upper Aquifer through vertical transfer. This study contributes to a better understanding of (1) salinization processes linked to connate marine water of different ages in the Matanza-Riachuelo Aquifer System and (2) different sources of flow paths delivering groundwater to the upper and lower sectors of the confined Puelche Aquifer. The knowledge generated from this study can help to understand groundwater salinization processes in other aquifer systems around the world and support groundwater management plans across the MRRB.

Locating Volcanic Earthquakes and Tremors Using Delay Time and Amplitude Ratio Information from Cross-Correlation Functions

AbstractVolcanic tremors and earthquakes must be monitored to gain insights into volcanic activity. Localization of their sources is often challenging because of the unclear onset of seismic waves, particularly when the volcanic activity increases before and during an eruption. Existing alternative techniques to locate the seismic sources are based on the information on the spatial amplitude distribution or the travel-time difference of seismic waves. Exploring the idea of combining both information for source location determination, we propose a new location method that uses the amplitude and travel-time difference information obtained from the unnormalized cross correlations of seismic data. Evaluation using volcanic earthquakes that occurred in 2020 at Tokachidake volcano, Japan, reveals an improvement in location accuracy compared to existing methods using individual information. Analysis of an episode of volcanic tremors and earthquakes accompanying a rapid tilt change event on 14 September 2020 reveals that during the inflation of the crater area, reliable seismic source locations with an error of ≤1 km become more concentrated at around 0.6 km beneath the 62-2 crater, in which the most recent eruptive activity had occurred. Such changes in source locations are associated with the movement of volcanic gas and hot water from the hydrothermal system below. Our proposed method is useful for locating and monitoring seismic source locations corresponding to volcanic fluid movements.

A High-Resolution Earthquake Catalog for the 2004 Mw 6 Parkfield Earthquake Sequence Using a Matched Filter Technique

Abstract We present the high-resolution Parkfield matched filter relocated earthquake (PKD-MR) catalog for the 2004 Mw 6 Parkfield earthquake sequence in central California. We use high-quality seismic data recorded by the borehole High Resolution Seismic Network combined with matched filter detection and relocations from cross-correlation derived differential travel times. We determine the magnitudes of newly detected events by computing the amplitude ratio between the detections and templates using a principal component fit. The relocated catalog spans from 6 November 2003 to 28 March 2005 and contains 13,914 earthquakes, which is about three times the number of events listed in the Northern California Seismic Network catalog. Our results on the seismicity rate changes before the 2004 mainshock do not show clear precursory signals, although we find an increase in the seismic activity in the creeping section of the San Andreas fault (SAF) (about ∼30 km northwest of the mainshock epicenter) in the weeks prior to the mainshock. We also observe a decrease in the b-value parameter in the Gutenberg–Richter relationship in the creeping section in the weeks prior to the mainshock. Our results suggest stress is increasingly released seismically in the creeping section, accompanied by a decreasing aseismic creeping rate before the mainshock occurrence. However, b-value and seismicity rates remain stable in the Parkfield section where the 2004 mainshock ruptured. This updated catalog can be used to study the evolution of aftershocks and their relations to afterslip following the 2004 Parkfield mainshock, seismicity before the mainshock, and how external stresses interact with the Parkfield section of the SAF and the 2004 sequence.

Airline reactions to high-speed rail entry: Rail quality and market structure

• HSR affects air traffic directly and indirectly via airfare adjustment. • Airfare plays different roles in competition, feeding and long-term effects. • HSR quality and pre-entry airline market structure affect airfare adjustment. • Feeding effect dominates competition effect, causing more airline CO2 emissions. • Airfare adjustment mitigates HSR-induced air traffic and airline CO2 emissions. Airfare reduction is proposed by a theoretical paper to be a possible source of observed air traffic increase in some markets where high-speed rail (HSR) enters and competes with airlines. This paper aims to empirically test whether and to what extent the air traffic impact is channeled by the adjustment in airfares. To understand the varying empirical results found in the literature, we examine heterogeneous airline responses in traffic and airfare in relation to HSR qualities measured by HSR-air travel time difference and pre-entry market structure of airline as well as decompose HSR impacts into competition, feeding and long-term effects. Using a panel dataset of Chinese air routes, we find that airfare adjustment plays crucial roles in channeling HSR’s air traffic impact. Our estimation suggests that HSR introduced over 16.5 million additional passengers to the sampled air routes in our study period, generating 2.17 million tons of extra CO2 emissions from air flights. However, these numbers would increase to 32.2 million additional passengers and 3.4 million tons of extra CO2 emissions after removing the price adjustment.

Tram Expansion Effects on Reaching the City Centres—Case Study of Tampere and Braunschweig

This manuscript is based on cooperation between the universities in Tampere, Finland and Braunschweig, Germany. New tram lines are being built or extended in both cities to provide better connections to public transportation and increase accessibility. This research presents case studies from each city that have successfully increased public transport (PT) ridership during recent years. The aim of this study is to compare and analyse the effects of tram expansion projects in Tampere and Braunschweig from the public transport network users’ viewpoint. These cities were selected because they are of similar size in terms of population and have similar modal shares of PT. Changes in accessibility to the city centres were analysed considering the tramline extensions. This was determined by calculating the travel time differences of the current network and the future network for both cities. For this total travel time, the ArcGIS Pro Service Area Tool was used to calculate the time taken to reach every grid of the investigation areas. The results vary due to the tram expansion and changes in the existing bus network.

Gendered mode choice preferences and characteristics for educational trips in Abbottabad, Pakistan: An empirical investigation

Educational trips are a major component of traffic in peak hours on working days. For proper trip forecasting, gendered preferences and dynamics must be understood. This study identifies gender-based model choices, preferences, and travel characteristics among school-going children and investigates the satisfaction level regarding public transport in Abbottabad, Pakistan. Using Slovin’s sampling method, a total of 370 samples were collected. Descriptive statistics, chi-square tests, and paired sample t-tests were conducted to determine the significant differences between genders and their travel characteristics. For public transport satisfaction, an index was constructed using indicators extracted from a rigorous literature review. The results show a significant difference between the mode choices and preferences of boys and girls. There was no significant difference in travel time, distance, and cost, but boys tended to make more trips than girls. The satisfaction level shows that girls had a more negative opinion about public transport than boys. This study argues that transport and urban planners must incorporate both gender preferences for developing transportation alternatives for students.