Value Of Travel Time Savings Research Articles

How Autonomous Driving May Affect the Value of Travel Time Savings for Commuting

Autonomous driving is being discussed as a promising solution for transportation-related issues and might bring some improvement for users of the system. For instance, especially high mileage commuters might compensate for some of their time spent traveling as they will be able to undertake other activities while going to work. At the same time, there are still many uncertainties and little empirical data on the impact of autonomous driving on mode choices. This study addresses the impact of autonomous driving on value of travel time savings (VTTS) and mode choices for commuting trips using stated-choice experiments. Two use cases were addressed – a privately owned, and a shared autonomous vehicle – compared with other modes of transportation. The collected data were analyzed by performing a mixed logit model. The results show that mode-related factors such as time elements, especially in-vehicle time and cost, play a crucial role for mode choices that include autonomous vehicles. The study provides empirical evidence that autonomous driving may lead to a reduction in VTTS for commuting trips. It was found that driving autonomously in a privately owned vehicle might reduce the VTTS by 31% compared with driving manually, and is perceived similarly to in-vehicle time in public transportation. Furthermore, riding in a shared autonomous vehicle is perceived 10% less negatively than driving manually. The study provides important insights into VTTS by autonomous driving for commuting trips and could be a base for future research to build upon.

Does context matter? A comparative study modelling autonomous vehicle impact on travel behaviour for Germany and the USA

This paper, for the first time, presents comparable projections of travel behaviour impacts of the introduction of autonomous vehicles (AVs) into the private car fleet for two countries, namely the USA and Germany. The focus is on fully autonomous vehicles (AVs) which allow drivers to engage in other activities enroute. Two 2035 scenarios – a trend scenario and an extreme scenario – are presented for both study countries. For these projections, we combine a vehicle technology diffusion model and an aspatial travel demand model. Factors that influence AV impact in the behavioural model are mainly new automobile user groups, e.g. travellers with mobility impairments, and altered generalized costs of travel, e.g. due to a lower value of travel time savings for car travel. The results indicate that AV penetrations rates might be higher in Germany (10% or 38% respectively) than in the USA (8% or 29% respectively) due to a higher share of luxury cars and quicker fleet turnover. On the contrary, the increase of vehicle mileage induced by AVs is not higher in Germany (+2.4% or +8.6% respectively) than in the USA (+3.4% or +8.6% respectively). This is mainly due to the lack of mode alternatives and lower fuel costs resulting in a higher share of travel times among the total generalized costs of travel in the USA. These results clearly indicate that context factors shaped by national policy will influence AV adoption and impact on travel demand changes. Based on these results the paper draws policy recommendations which will help to harness the advantages of AVs while avoiding their negative consequences.

Impact of ICT on multitasking during travel and the value of travel time savings: Empirical evidences from Mumbai, India

This study looks into the multitasking patterns for the developing world, while providing empirical evidences of the effect of multitasking on the value of travel time savings (VTTS). The multitasking behaviour during travel was studied, ascertaining the effect of various socio-economic variables, access to information and communication technologies (ICT), and travel related factors. Travel diary data was collected across the city of Mumbai, India for 1123 individuals capturing their revealed preferences on travel and multitasking during travel. It was observed that having a smartphone with an internet usage of more than one GB data had positive significant impacts on ICT dependent multitasking activities. In addition, the proportion of no-activity also significantly reduced with higher access to ICT. It was observed that the VTTS reduced by 26% for individuals who performed multitasking. Furthermore, for reading on a mobile device, usage of social media, messaging or talking to someone on phone, and for gaming, the VTTS reduced by 25%, 37%, and 16% respectively. Findings were used to make cross country comparisons and discuss policy implications.

АНАЛИЗ ТЕОРЕТИЧЕСКИХ ПОДХОДОВ К ОЦЕНКЕ ИЗДЕРЖЕК, СВЯЗАННЫХ С НЕНАДЕЖНОСТЬЮ ТРАНСПОРТНЫХ КОРРЕСПОНДЕНЦИЙ ГОРОДСКОГО ПАССАЖИРСКОГО ТРАНСПОРТА И ВРЕМЕНЕМ ТРАНСПОРТНЫХ ПЕРЕДВИЖЕНИЙ ГОРОДСКОГО НАСЕЛЕНИЯ

The overview of some theoretical approaches to the mechanism of economic valuation of travel time variability and the value of travel time savings of urban passenger transport is provided. Each estimate depends on the demographic characteristics of the population, the type of transport, time, location and purpose of the trip, as well as the available choice of alternatives. The decisions of experts in a context of consumption choice based on utility maximization, subject to constraints on income and the minimum amount of time required by each activity are described. There in sum, there is a broad consensus on the approach adopted and the relevant variables and categories, as well as a degree of similarity in the specific values recommended.

Estimating policy values for in-vehicle comfort and crowding reduction in local public transport☆

This study estimates policy values for comfort, defined as getting a seat, and crowding reduction on board local public transport in Sweden. We use stated-preference (SP) data and present crowding as a mode-neutral crowding level among the standing travelers depicted in images presented to the respondents. We analyze whether there are differences in the willingness to pay (WTP) for comfort and crowding reduction among the three largest urban areas in Sweden. In general, we find no significantly different preferences for sitting and crowding reduction among the three urban areas. Still, the point estimates differ in some cases, indicating that there may be differences across the three urban areas, but the estimates have large confidence intervals that overlap each other. Also, these differences are likely to have resulted from mode-share differences and not from differences in preferences across the urban areas. Some significant differences are found among the modes, for example, a higher disutility of standing on a bus versus on a tram. These mode-specific estimates can be used as policy values for a given tram line or metro line. Nevertheless, we also pooled the data suggesting average WTP estimates for sitting and crowding reductions that can be used for national cost–benefit analysis policy in all large urban areas in Sweden where crowding on local public transport occurs. Importantly, analysis of heterogeneity and SP-design differences shows that the results are in line with empirical knowledge of the value of travel time savings.

New appraisal values of travel time saving and reliability in Great Britain

This paper provides an overview of the study ‘Provision of market research for value of time savings and reliability’ undertaken by the Arup/ITS Leeds/Accent consortium for the UK Department for Transport (DfT). The paper summarises recommendations for revised national average values of in-vehicle travel time savings, reliability and time-related quality (e.g. crowding and congestion), which were developed using willingness-to-pay (WTP) methods, for a range of modes, and covering both business and non-work travel purposes. The paper examines variation in these values by characteristics of the traveller and trip, and offers insights into the uncertainties around the values, especially through the calculation of confidence intervals. With regards to non-work, our recommendations entail an increase of around 50% in values for commute, but a reduction of around 25% for other non-work—relative to previous DfT ‘WebTAG’ guidance. With regards to business, our recommendations are based on WTP, and thus represent a methodological shift away from the cost saving approach (CSA) traditionally used in WebTAG. These WTP-based business values show marked variation by distance; for trips of less than 20 miles, values are around 75% lower than previous WebTAG values; for trips of around 100 miles, WTP-based values are comparable to previous WebTAG; and for longer trips still, WTP-based values exceed those previously in WebTAG.

Environmental impact and travel time savings of a new monorail system in colombo’s commuting traffic

This study estimates the environmental impact and the value of travel time savings for commuters who travel to Colombo city in traffic congestion when the proposed monorail system is in place. The model considers an introduction of a monorail into a mono-centric city with symmetrically distributed radial highways converging toward the central business district (CBD), with an inelastic commuter demand. We compare the CO2 emission amount as well as aggregate travel time savings from different monorail scenarios, with the introduction of a toll as a necessary condition to generate an efficient outcome. The results show that for a monorail running at an average speed of 40km/h a length of 26.8km from the CBD will optimize investment and contribute travel time savings of 105 million Rs. per day or 189 million USD per year to the Sri Lankan economy, resulting in the CO2 emission reduction by 42%. A sensitivity analysis is conducted to evaluate the effects of monorail speed, commuter income, and population growth.

Value of travel time savings and willingness to pay for regional aviation

Despite their immense importance to regional and remote communities, regional air services are often commercially not viable and need public support. That support, and hence the existence of such lifeline services, is often questioned by stakeholders and policy makers. While the value of these services is high to the passengers and businesses that are located in regional, rural and remote areas, there is only anecdotal and no robust evidence available on the value of such services to people who live in metropolitan areas. This paper applies mixed logit choice models to a large sample of the Sydney metropolitan area to establish, for a first time, empirical evidence on the value of travel time savings (VTTS) and the willingness to pay for regional air services. While car is the most preferred option for regional travel (chosen most), we find a median willingness to pay of $99 per hour for leisure travel via plane and $153 per hour for business travel. Additional analysis on VTTS for different modes across leisure versus business travel is also conducted, providing for a more detailed understanding of each traveller type and willingness to pay differences between the various groups. The findings are of substantial value to regional airlines, airports, regulators, funding bodies and policy makers as they show that regional aviation is not only invaluable to the regions but also of high value to residents and business travellers residing in metropolitan areas.

Income effects, cost damping and the value of time: theoretical properties embedded within practical travel choice models

Mackie et al. (Values of travel time savings in the UK. Report to Department for Transport. Institute for Transport Studies, University of Leeds & John Bates Services, Leeds and Abingdon, 2003) proposed an identity relating the value of time (VoT) for commute and leisure travel to income and travel cost, reporting the prevalence of ‘cost damping’ (i.e. the phenomenon where VoT increases as travel cost increases). This identity (or a variant thereof) has been adopted within official methods for estimating VoT in the UK, Switzerland and The Netherlands. The present paper shows that Mackie et al.’s identity: (i) implies linear preferences, not strictly convex preferences as reported by Mackie et al.; (ii) complies with homogeneity and symmetry by construction; (iii) complies with adding-up if and only if VoT is unit elastic with respect to income; (iv) complies with negativity if VoT is unit elastic or greater with respect to income; (v) violates both adding-up and negativity in the case of the 2003 UK national VoT study. We propose alternative identities which comply with adding-up and homogeneity by construction, and offer comparable fit to Mackie et al.’s identity on the UK VoT dataset. We also find that the imposition of adding-up and negativity on Mackie et al.’s identity, through appropriate constraint on model estimation, leads to an increase of around 20% in valuations from the 2003 UK dataset.

How much is too much for tolled road users: Toll saturation and the implications for car commuting value of travel time savings?

The current practice of forecasting the demand for new tolled roads typically assumes that car users are prepared to pay a higher toll for a shorter journey, and they will keep doing so as long as the toll cost is not higher than their current value of travel time savings. Practice ignores the possibility that there could be a point when motorists stop driving on toll roads due to a toll budget constraint. The unconstrained toll budget assumption may be valid in networks where the addition of a new toll road does not result in a binding budget constraint that car users may have for using toll roads (although it could also be invoked for existing tolled routes through a reduction in use of a tolled route). In a road network like Sydney which offers a growing number of (linked) tolled roads, the binding budget constraint may be invoked, and hence including additional toll links might in turn reduce the car users’ willingness to pay for toll roads to save the same amount of travel time. When this occurs, car users are said to reach a toll saturation point (or threshold) and begin to consider avoiding one or more toll roads. Whilst toll saturation has important implications for demand forecasting and planning of toll roads, this type of behaviour has not been explored in the literature. We investigate the influence that increasing toll outlays has on preferences of car commuters to use one or more tolled roads as the number of tolled roads increases. The Sydney metropolitan area offers a unique laboratory to test this phenomenon, with nine tolled roads currently in place and another five in planning. The evidence supports the hypothesis that the value of travel time savings decreases as a consequence of toll saturation.

Experience conditioning in commuter modal choice modelling – Does it make a difference?

This paper investigates the impact of decision maker’s experience on model elasticities and predicted market share, using data collected in Sydney on commuter mode choice. Usage frequency is used as a proxy for experience and two separate mode choice models are estimated – one with experience conditioning choice and one without. Key model outputs are compared and we find that differences in the value of travel time savings and model elasticities are very marked. This suggests that ignoring experience that one has with each alternative in their choice set may be a candidate source of error in travel demand forecasts. We develop a method to obtain the level of experience for use in application of choice models to increase their prediction power.

Vehicle value of travel time savings: Evidence from a group-based modelling approach

The value of travel time savings (VTTS) accounts for a majority of the total user benefits in economic appraisal of transport investments. This means that having an accurate estimate of VTTS for different segments of travel continues to retain currency, despite there being a rich literature on estimates of VTTS for different travel modes, travel purposes, income groups, life cycles, and distance bands. In contrast, there is a dearth of research and evidence on vehicle VTTS, although joint travel by car is an important segment of travel. This paper fills this gap by developing a group-based modelling approach to quantify the vehicle VTTS and compares this with the VTTS for a driver with and without a passenger. An online survey was conducted in Sydney in 2014 and the data used to obtain a number of new empirical estimates of vehicle and driver VTTS. The new evidence questions the validity of various assumptions adopted in current practice for valuing the time savings of car passengers and multiple occupant cars.

Agent-based Congestion Pricing and Transport Routing with Heterogeneous Values of Travel Time Savings

An existing agent-based simulation framework and congestion pricing methodology is extended towards a consistent consideration of non-linear, user- and trip-specific values of travel time savings (VTTS). The heterogeneous VTTS are inherent to the model and result from each agent's individual time pressure. An innovative approach is presented which accounts for the non-linear, user- and trip-specific VTTS (i) when converting external delays into congestion tolls and (ii) when generating new transport routes. The innovative pricing and routing methodology is applied to a real-world case study of the Greater Berlin area, Germany. The proposed methodology performs better than assuming a constant value of travel time savings or randomizing the routing relevant costs. The improved consistency of setting congestion toll levels, identifying transport routes and evaluating travel plans is found to result in a higher system welfare.

How the values of travel time change when a panel data around a new tram implementation is used

Using a dataset with transport choices of the same set of individuals (college students from University of La Laguna), we built a novel three waves panel data around a tramline implementation in the Santa Cruz-La Laguna corridor in Tenerife, Spain. The first two waves were conducted in 2007, just before the tram implementation. They collect information about Revealed Preferences (RP) of actual transport mode choices (car, bus and walk) and about Stated Preferences (SP) in a simulated scenario considering a hypothetical binary choice between the tram and the transport mode currently chosen by the students. The third wave gathers information about RP in 2009, two years after the tram started operating. With this information, we estimate several multinomial logit models and panel mixed logit models with error components. The aim of this paper is to evaluate how the estimation of the Values of Travel Time Savings (VTTS) changes when comparing the results obtained with models that only consider information before or after the tram implementation with that obtained with a panel data approach using the three waves simultaneously (RP/SP in 2007 and RP in 2009). We obtain a better statistical fit to data and, according to our study context, more reasonable VTTS using a panel data approach combining before and after information and both revealed and stated preferences. Our results suggest that when a new transport mode is implemented, the VTTS obtained with models than only consider prior or later periods of time can be underestimated and hence lead to wrong valuations of the benefits associated with the new alternative, even when stated preferences are used to anticipate the change in the transport system.

A Simple Stated Preference Tool for Estimating the Value of Travel Time in Rural Africa

Despite its importance in benefit-cost analyses in the water supply, transportation, and health care sectors, there are relatively few empirical estimates of the value of travel time savings (VTT) in low-income countries, particularly in rural areas. Analysts instead often rely on a textbook “rule of thumb” of valuing time at 50% of prevailing unskilled wage rates, though these benchmarks have little empirical support in these settings. We estimate the value of travel time through the use of a repeated discrete choice stated preference exercise. We asked 325 rural households in Meru County, Kenya to rank two new hypothetical water sources against their current water source. The two new hypothetical sources were described as safe and reliable to use, but varied only in their distance from the household and the price charged per water container. Results from random-parameters logit models imply an average value of travel time of 18 Ksh/hr, and generally support the 50% rule. These models produce the first individual-level VTT estimates reported in a low-income setting, and indicate statistically-significant heterogeneity in VTTs, though the heterogeneity is not well correlated with observables. A latent-class approach identifies four classes of respondents: one class (about one third of respondents) values time very highly (49 Ksh/hr), one poorer group values time hardly at all (less than 1 Ksh/hr), and two groups value time at approximately 9 Ksh/hr.

Web-based versus Paper-based Survey Data: An Estimation of Road Users’ Value of Travel Time Savings

This study estimates the value of travel time savings (VTTS) by using four types of data sources: stated preference (SP) responses and revealed preference (RP) responses, each from a paper-based survey and a web-based survey. All data were collected in Atsugi City, Japan, in December 2010. In addition to a simple model with SP response data, a combined RP/SP model, a combined paper/web model, and combined RP/SP+paper/web models are formulated to integrate the different data sources. The results show that the VTTS estimated from paper-based survey data could be significantly different to those estimated from web-based survey data. In addition, the combined RP/SP model could improve the model fitness significantly. The combined paper/web model could not improve significantly the model fitness when compared to a paper-only model or web-only model. The combined RP/SP+paper/web model, however, could give the best estimation results, enabling us to obtain reasonable VTTS estimates.

On the identification of thresholds in travel choice modelling

In this paper we demonstrate different approaches for estimating thresholds with respect to attribute differences in discrete choice models. The proposed new transformation functions can easily be applied in estimation software. The usefulness of these functions is tested with synthetic data. Extensive simulation shows that many observations are necessary to detect thresholds. And furthermore, the value of travel time savings of a model ignoring these thresholds is biased. The application to stated choice data reveals a significant threshold. However, the cause and the precise form of this threshold cannot be inferred from the data. The presented approach might also be useful to model thresholds in other contexts of choice behaviour.

The variation in the value of travel-time savings and the dilemma of high-speed rail in China

This paper examines the variation in the value of travel-time savings (VTTS), a fundamental element determining the market demand for high-speed rail. Following a review of time allocation theories, a time allocation model for general travel behavior is proposed as a further elaboration of Evans’ (1972) activities analysis. There are relationships among activities that can be expressed using a linear inequality to show the constraints on the arrangement of activities. This model indicates that two or more activities can be simultaneously rearranged to improve time management, which may be a source of variation in VTTS. This time allocation model can explain why large-scale high-speed rail construction in China faces significant market risks and a high likelihood of economic loss. Data from a new ticket sales and booking system for railway passengers indicate that passengers prefer conventional overnight sleeper trains, rather than high-speed trains, for long-distance travel, which supports the analysis of the time allocation model.

Quantifying and decomposing the uncertainty in appraisal value of travel time savings

This paper is concerned with computing interval estimates for appraisal values of travel time savings (VTTS) for non-work journeys. The paper has important conclusions relating to the benefits, in terms of uncertainty in appraisal VTTS, of resampling the base year VTTS and improving on the precision of the estimate of the GDP elasticity in the uprating equation. Importantly it is shown that the interval widths increase dramatically as VTTS is forecast further into the future. This has a significant modelling implication in that it is the uncertainty associated with the process of uprating base estimates of VTTS which results in the large interval width, rather than that associated with the base year VTTS estimate. This in turn implies a need to regularly resample the base VTTS, so as to avoid excessive temporal extrapolation of the base VTTS.

The digital revolution and worthwhile use of travel time: implications for appraisal and forecasting

Savings in travel time and more specifically their monetary value typically constitute the main benefit to justify major investment in transport schemes. However, worthwhile use of travel time is an increasingly prominent phenomenon of the digital age. Accordingly, questions are increasingly being asked regarding whether values of time used by countries around the world based on their appraisal approaches are too high. This paper offers the most comprehensive examination of our theoretical and empirical understandings of international appraisal approaches and how they account for worthwhile use of travel time. It combines the economics perspective with wider social science insight and reaches the conclusion that past revolutions in transport that have made longer and quicker journeys possible are now joined by a digital revolution that is reducing the disutility of travel time. This revolution offers potential economic benefit that comes at a fraction of the cost of major investments in transport that are predicated on saving travel time. The paper highlights the challenges faced in both current and indeed potential alternative future appraisal approaches. Such challenges are rooted in the difficulty of measuring time use and productivity with sufficient accuracy and over time to credibly account for how travel time factors into the economic outcomes from social and working practices in the knowledge economy. There is a need for further research to: establish how improvements in the opportunities for and the quality of worthwhile use of travel time impact on the valuation of travel time savings for non-business travel; improve our understanding of how productive use of time impacts on the valuation of time savings for business travellers; and estimate how these factors have impacted on the demand for different modes of travel.