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This study examines the effects of vehicle size on driver impressions and behavioral intentions. Study 1 tested whether vehicle size (large vs. small) affects perceived physical size (height, body shape) through socioeconomic status (SES). We found that large (vs. small) vehicle drivers were perceived as tall (vs. short), and this perception was mediated by the drivers’ estimated SES (but not by body shape). Study 2 focused on aggressive behavioral intentions (e.g. honking) toward other drivers, examining whether the relationship between vehicle size and intention was serially mediated by estimated physical size and traits (aggression, power). Here, large (vs. small) vehicle driver were perceived as tall (heavy) and possessing high power (high aggression), which is related to less (more) aggressive behavioral intention toward the driver. Our study suggests that individuals perceive other drivers’ physical sizes differently, and this perception is associated with differences in behavioral responses toward other drivers. [ABSTRACT FROM AUTHOR]

Previous research suggests that higher fuel prices generally lead to reduced traffic flows. We argue that higher fuel prices may increase traffic flows on expressways that provide shorter trips than local roads. The Hanshin Expressway in Japan, which runs through the metropolitan area surrounding Osaka and Kobe, provides an appropriate research context. We analyzed 16.57 million hourly traffic flow observations and discovered that higher fuel prices lead to increased expressway traffic flows. In our dataset, vehicles were divided into small and standard private vehicles as well as small, medium, and large commercial vehicles (such as buses and trucks). Based on statistical tests, we found that small private cars have higher elasticity (0.13) than standard private cars (0.08), whereas large commercial vehicles have higher elasticity (0.35) than medium and small ones. Moreover, medium commercial vehicles have similar elasticity (0.22) to small ones (0.21). Additionally, an analysis of elasticities in peak/off-peak hours across weekdays/weekends, medium-run elasticities, and asymmetric effects shed light on drivers' behavior. Thus, our results provide valuable insights for policymakers and management strategists. • Fuel prices positively affect traffic flows on Japan's Hanshin Expressway. • Small private cars have higher elasticity (0.13) than standard private cars (0.08). • Large commercial vehicles have higher elasticity (0.35) than medium and small ones. • Medium commercial vehicles have similar elasticity (0.22) to small ones (0.21). • Peak/off-peak hours, medium-run, and asymmetric effects are also examined. [ABSTRACT FROM AUTHOR]

• Investigating influencing factors and assessing drivers' gap acceptance (GA). • Basis for initiating driving actions in automated vehicles. • GA increased by the approaching vehicle's size and decreased by its higher speeds. • Older and more conservative participants selected larger GA. • No one-fits-all solution for accepted time gaps in traffic. As a social system, traffic requires the coordination between different involved road users, particularly in shared spaces (e.g., parking areas) with fewer statutory regulations and hence more ambiguous encounters. By anticipating the development of driving scenes and adapting own driving actions, drivers maintain individually varying safety margins, such as accepted time gaps, to surrounding traffic participants. However, drivers' gap acceptance (GA) was shown to be influenced by situational factors and driver characteristics. In order to apply expectable interactions in mixed traffic, involving manual and automated vehicles (AVs), intuitive gaps in traffic flow need to be selected by AVs when initiating parking actions. Derived time gaps of manual drivers could provide a basic orientation for intuitive driving functions in AVs. Thus, the current experimental study assessed manual drivers' GA in a parking area scenario. Real-world video material was used to investigate the effects of interaction partners, their encountering speeds and drivers' age and sensation seeking on GA. In the study, 42 participants (including two age groups: 18–30 years vs ≥ 45 years) indicated their GA when initiating a left-turn parking maneuver in front of approaching vehicles. The study examined three interaction partners (motorcycle, passenger car, truck), each approaching at six different speed levels (10–35 km/h). The results revealed that selected time gaps increased as vehicle size increased, with the largest GA for the truck and the smallest gaps for the motorcycle. Moreover, time gaps decreased at higher approaching speeds of the interaction partners. In addition, older participants selected more conservative gaps and participants with higher sensation seeking scores accepted lower time gaps to initiate a parking maneuver. The results of the current study revealed that there is no one single time gap that is always considered as appropriate to initiate parking actions. For intuitive interaction capabilities in AVs and to support smooth encounters in mixed traffic, the speed of the approaching interaction partners should be considered as an essential situational factor when initiating parking maneuvers. To consider individual driving style preferences (e.g., due to driver age) and support user acceptance, selectable driving style profiles should be available in AVs as a form of customization. [ABSTRACT FROM AUTHOR]

• Vehicles crashed in had poorer IIHS crash ratings for drivers 70+ than ages 35–54. • Vehicles crashed in had fewer safety features for drivers 70+ than ages 35–54. • Vehicles crashed in were older for drivers 70+ than ages 35–54. • Newer, safer vehicles may reduce crash-related fatalities for drivers ages 70+. Introduction: Age-related frailty leaves older drivers with the greatest fatality risk when involved in a crash compared with younger demographics. This study explored how vehicle features differed between crash-involved older and middle-aged drivers and estimated how those differences contribute to excess older driver fatalities. Methods: We merged Florida's crash data from 2014–2018 with Insurance Institute for Highway Safety and Highway Loss Data Institute databases. We compared the distribution of passenger vehicle age, type, size, and safety features among crash-involved older drivers (ages 70 and older) with crash-involved middle-aged drivers (ages 35–54). From logistic regression models, we estimated declines in older driver fatalities if they drove vehicles like those driven by middle-aged drivers under all and side-impact crash scenarios. Results: Older drivers in crashes were more likely to be in vehicles that were lighter, older, and without standard electronic stability control, standard head-protecting side airbags, and ratings of good in two IIHS crash tests than middle-aged drivers. In adjusted models, the fatality risk for older drivers in all crashes was significantly higher when ESC was not standard (odds ratio [OR], 1.37; 95% confidence interval [CI], 1.12–1.68) or when driving small passenger cars relative to large SUVs (OR, 2.02; 95% CI, 1.25–3.26); in driver-side crashes, the fatality risk doubled when vehicles did not have standard head-protecting side airbags (OR, 2.03; 95% CI, 1.58–2.62). If older drivers drove vehicles similar to middle-aged drivers, we estimated 3.3% and 4.7% fewer deaths in all and side-impact crashes, respectively. Conclusions: These results contribute to evidence suggesting that newer, more crashworthy vehicles with crash mitigation features benefit older drivers because of their heightened risk of crash-related fatality. Practical Applications: At a minimum, older drivers should aim to drive equipped vehicles with widely available features proven to reduce fatalities. [ABSTRACT FROM AUTHOR]

• First-time investigation of light-band eHMIs for pedestrians' interaction with highly automated vehicles in Japan. • Light-band eHMIs contributed to pedestrians' willingness to cross, trust and perceived safety in Japan. • Similar positive findings of light-band eHMIs when comparing pedestrians' subjective evaluation in Japan and Germany. • Identification of possible side effects of malfunctioning eHMIs: Japanese relied on eHMI, although the eHMI contradicted the vehicle kinematics. In the near future, pedestrians will face highly automated vehicles on the roads. Highly automated vehicles (HAVs) should have safety-enhancing communication tools to guarantee traffic safety, e.g., vehicle kinematics and external human–machine interfaces (eHMIs). Pedestrians, as highly vulnerable road users, depend on communication with HAVs. Miscommunication between pedestrians and HAVs could quickly result in accidents, and this, in turn, could cause severe impairments for pedestrians. Light-band eHMIs have the potential to enhance traffic safety. However, eHMIs have been less explored in Japan so far. As a first-time approach, this experimental online study shed light on the effect of a light-band eHMI on Japanese pedestrians (N =99). In short video sequences, the participants interacted with two differently sized HAVs equipped with light-band eHMI. We investigated the effect of vehicle size (small vs. large), eHMI status (no eHMI vs. static eHMI vs. dynamic eHMI), and vehicle kinematics (yielding vs. non-yielding) on pedestrians' willingness to cross, trust, and perceived safety. To investigate possible side effects of eHMIs, we also included experimental conditions in which the eHMI mismatched the vehicle's kinematics. Results revealed that Japanese were more willing to cross the street and indicated higher trust- and safety ratings when they received information about the vehicle's intention and automation status (dynamic eHMI) compared to when they received no information (no eHMI) or only about the vehicle automation status (static eHMI). Surprisingly, Japanese participants tended to rely on the eHMI when there was mismatching information between eHMI and vehicle kinematics. Overall, we concluded that light-band eHMIs could contribute to a safe future interaction between pedestrians and HAVs in Japan under the requirement that the eHMI is in accordance with vehicle kinematics. [ABSTRACT FROM AUTHOR]

Future automated vehicles (AVs) of different sizes will share the same space with other road users, e. g., pedestrians. For a safe interaction, successful communication needs to be ensured, in particular, with vulnerable road users, such as pedestrians. Two possible communication means exist for AVs: vehicle kinematics for implicit communication and external human-machine interfaces (eHMIs) for explicit communication. However, the exact interplay is not sufficiently studied yet for pedestrians' interactions with AVs. Additionally, very few other studies focused on the interplay of vehicle kinematics and eHMI for pedestrians' interaction with differently sized AVs, although the precise coordination is decisive to support the communication with pedestrians. Therefore, this study focused on how the interplay of vehicle kinematics and eHMI affects pedestrians' willingness to cross, trust and perceived safety for the interaction with two differently sized AVs (smaller AV vs. larger AV). In this experimental online study (N = 149), the participants interacted with the AVs in a shared space. Both AVs were equipped with a 360? LED light-band eHMI attached to the outer vehicle body. Three eHMI statuses (no eHMI, static eHMI, and dynamic eHMI) were displayed. The vehicle kinematics were varied at two levels (non-yielding vs. yielding). Moreover, "non-matching" conditions were included for both AVs in which the dynamic eHMI falsely communicated a yielding intent although the vehicle did not yield. Overall, results showed that pedestrians' willingness to cross was significantly higher for the smaller AV compared to the larger AV. Regarding the interplay of vehicle kinematics and eHMI, results indicated that a dynamic eHMI increased pedestrians' perceived safety when the vehicle yielded. When the vehicle did not yield, pedestrians' perceived safety still increased for the dynamic eHMI compared to the static eHMI and no eHMI. The findings of this study demonstrated possible negative effects of eHMIs when they did not match the vehicle kinematics. Further implications for a holistic communication strategy for differently sized AVs will be discussed. [ABSTRACT FROM AUTHOR]

Future automated vehicles (AVs) of different sizes will share the same space with other road users, e. g., pedestrians. For a safe interaction, successful communication needs to be ensured, in particular, with vulnerable road users, such as pedestrians. Two possible communication means exist for AVs: vehicle kinematics for implicit communication and external human-machine interfaces (eHMIs) for explicit communication. However, the exact interplay is not sufficiently studied yet for pedestrians' interactions with AVs. Additionally, very few other studies focused on the interplay of vehicle kinematics and eHMI for pedestrians' interaction with differently sized AVs, although the precise coordination is decisive to support the communication with pedestrians. Therefore, this study focused on how the interplay of vehicle kinematics and eHMI affects pedestrians' willingness to cross, trust and perceived safety for the interaction with two differently sized AVs (smaller AV vs. larger AV). In this experimental online study (N = 149), the participants interacted with the AVs in a shared space. Both AVs were equipped with a 360° LED light-band eHMI attached to the outer vehicle body. Three eHMI statuses (no eHMI, static eHMI, and dynamic eHMI) were displayed. The vehicle kinematics were varied at two levels (non-yielding vs. yielding). Moreover, “non-matching” conditions were included for both AVs in which the dynamic eHMI falsely communicated a yielding intent although the vehicle did not yield. Overall, results showed that pedestrians' willingness to cross was significantly higher for the smaller AV compared to the larger AV. Regarding the interplay of vehicle kinematics and eHMI, results indicated that a dynamic eHMI increased pedestrians' perceived safety when the vehicle yielded. When the vehicle did not yield, pedestrians' perceived safety still increased for the dynamic eHMI compared to the static eHMI and no eHMI. The findings of this study demonstrated possible negative effects of eHMIs when they did not match the vehicle kinematics. Further implications for a holistic communication strategy for differently sized AVs will be discussed.

Objective: It is of critical importance to develop socially sensitive vehicles that will enhance pedestrians’ sense of comfort and safety. The current study is the first to extend these effects to vehicles, by investigating individual comfort distance in virtual reality with regard to vehicles that vary in terms of size, viewing angle and anthropomorphized emotional expression. Furthermore, we investigate the effect of individual differences in terms of height, anxiety and aggression. Method: Forty-four individuals were presented with three-dimensional stimuli of vehicle models differing in size and viewing angle in virtual reality and positioned them at the distance they felt the most comfortable with. Results: Our results show that individuals are more comfortable standing further from larger vehicles and when presented with the front versus the rear view of a vehicle. Moreover, the distance from vehicles was negatively associated with the height of the individuals. Conclusion: This paper suggests that it is important for designing self-driving and autonomous vehicles to consider that vehicle size and direction as well as pedestrian’s height may impact the comfort distance felt by pedestrians. These data have clear implications for vehicle design, including self-driving and autonomous vehicles. KEY POINTS What is already known: Individuals maintain larger distances when in front of individuals/agents than beside or behind them. Individuals provide greater physical space to larger agents (animals and/or humans). No previous study investigated the effect of vehicle size, view angle, and fascia on the comfort distance preferred by individuals as pedestrians. What it adds: Individuals are more comfortable standing further from larger vehicles. Individuals prefer to place more distance between themselves and a vehicle when seeing it from the front versus the rear. Shorter individuals adopt a larger distance from vehicles irrespective of vehicle size and viewing side.

Objective: It is of critical importance to develop socially sensitive vehicles that will enhance pedestrians' sense of comfort and safety. The current study is the first to extend these effects to vehicles, by investigating individual comfort distance in virtual reality with regard to vehicles that vary in terms of size, viewing angle and anthropomorphized emotional expression. Furthermore, we investigate the effect of individual differences in terms of height, anxiety and aggression. Method: Forty-four individuals were presented with three-dimensional stimuli of vehicle models differing in size and viewing angle in virtual reality and positioned them at the distance they felt the most comfortable with. Results: Our results show that individuals are more comfortable standing further from larger vehicles and when presented with the front versus the rear view of a vehicle. Moreover, the distance from vehicles was negatively associated with the height of the individuals. Conclusion: This paper suggests that it is important for designing self-driving and autonomous vehicles to consider that vehicle size and direction as well as pedestrian's height may impact the comfort distance felt by pedestrians. These data have clear implications for vehicle design, including self-driving and autonomous vehicles. KEY POINTS What is already known: Individuals maintain larger distances when in front of individuals/agents than beside or behind them. Individuals provide greater physical space to larger agents (animals and/or humans). No previous study investigated the effect of vehicle size, view angle, and fascia on the comfort distance preferred by individuals as pedestrians. What it adds: Individuals are more comfortable standing further from larger vehicles. Individuals prefer to place more distance between themselves and a vehicle when seeing it from the front versus the rear. Shorter individuals adopt a larger distance from vehicles irrespective of vehicle size and viewing side. [ABSTRACT FROM AUTHOR]

Although there are several policies for promoting green vehicles, green vehicles have yet to penetrate the market to the extent desired. To attain the goal, a complete understanding of consumers’ preferences of green vehicles is essential. This paper proposes and specifies the fuel-type choice models among conventional gasoline vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and electric vehicles by vehicle size using the stated preferences data collected in Seoul, Korea. The results highlight the need to accommodate the correlation between similar alternatives and the unobserved heterogeneity within the context of choosing a green vehicle. The choice probabilities of green vehicles are affected by the relative impacts of the vehicles’ attributes and socio-demographic variables, and both of these variables are affected by the sizes of the vehicles. For compact size and mid-size vehicles, the effects of operating costs were less than those of purchase prices; however, for the subcompact vehicles, the effects of operating cost were greater than those of purchase price. The parameter of operating costs was not statistically significant in the full-size model. With respect to electric vehicles, the availability of fuel stations would be more important in Seoul than in the U.S. These results can also be useful for policy makers in that they provide information about the impact of green vehicles’ attributes on the choice probabilities of green vehicles. [ABSTRACT FROM AUTHOR]

Knowledge of real-world greenhouse gas emission rates for traffic is necessary for forecasting transport greenhouse gas emissions. This paper presents greenhouse gas emission rates that assist forecasting and modelling greenhouse gas emissions from light vehicles, i.e. private passenger vehicles and light commercial vehicles under realistic traffic conditions. It develops confidence intervals for market shares by categories for fuel or energy efficiency on the Australian market for new light vehicles for the period 2016–2030. The model estimates realistic market scenarios by simulating likely variations of capital and running costs of alternatives for car buyers and by considering buyers’ willingness-to-pay for fuel/energy efficiency. The results suggest that market forces will be insufficient to promote battery electric vehicles and plug-in hybrid electric vehicles in Australia. On average the widths of the 95% confidence intervals for greenhouse emission rates are about 10–15% of the magnitudes of the emission rates, so that analysts can forecast transport greenhouse gas emissions with a reasonable level of certainty. The study suggests that policy interventions to accelerate the uptake of low or zero emitting vehicles may be required. [ABSTRACT FROM AUTHOR]

[Display omitted] Analysts need to consider the shift of light-duty vehicle sales from cars to light trucks to accurately project fuel consumption, greenhouse gas emissions, and consumer spending. We find that energy consumed by on-road light-duty vehicles in the United States can vary by 10% by changing assumptions regarding the sales mix. Scenarios aligned with third-party forecasts, assuming a greater sales proportion of light trucks and fewer cars, yield petroleum consumption 3–8% higher than forecasts from the U.S. Energy Information Administration (EIA), with greenhouse gas emissions 5–7% higher and a 4–9% increase in consumer spending on vehicles and fuel. This incremental energy consumption can be offset by additional technologies for these vehicles. If most sedans were phased out in favor of larger sport utility vehicles, we find a sales share of 30% battery electric vehicles or 39% hybrid electric vehicles would equal the emissions of the EIA Reference Case. [ABSTRACT FROM AUTHOR]

Abstract: Evaluating risk perception in car following is important for understanding driver behavior in close following. A new model of risk perception in car following is proposed in this study, in which the risk perceived by the driver of a following car is divided into two parts: the tailgating risk involved in following the leading vehicle, which is relatively stable from the driver’s viewpoint, and the intuitive risk perception arising from the remaining field of view of the surrounding environment, with oncoming vehicles rushing toward the driver or stationary objects being passed at a relatively high speed. We proposed that the driver does not always think that the leading vehicle is dangerous; on the contrary, a driver may feel safer when he/she gets closer to the leading vehicle if he/she perceives obvious risks from the environment. A driving-simulator experiment was designed to validate the proposed model, in which environmental risk was increased by adding a number of cars travelling in the opposite direction in the adjacent lane. Adjustments of the distance headway by 48 subjects were recorded. The results provided positive support for the proposed model to a certain extent. It was found that when vehicles came in the opposite direction, drivers showed a tendency to decrease their distance headways, but this tendency actually increased the risk. Additionally, data were collected on comfortable and minimum safe distances that the drivers kept, and a significant interaction effect of the speed and the size of the leading vehicle on distance headway was observed. [Copyright &y& Elsevier]

A sample of 496 car and sport utility vehicle (SUV) drivers responded to questionnaires that examined attitudes toward vehicle size and safety. The aim of this research is to determine whether drivers perceive larger vehicles to be safer and whether this concern for safety motivates drivers to purchase SUVs. Alternatively, non-safety influences are also examined, including environmental concern, vehicle power, prestige, and vehicle utility. Perceptions that large vehicle are safer, off-road use, and prestige all relate strongly to SUV use. The safety arguments raised by SUV drivers appear to be based on an egocentric concern for “bigger is safer” rather than a broader understanding of vehicle fleet safety. To encourage sustainable transport, it is suggested that road safety policy should shift drivers' concerns from personal collision protection to overall road user protection. [ABSTRACT FROM AUTHOR]

Abstract: Hybrid powertrains are considered to be a promising method to raise the overall fuel efficiency of passenger cars. They are predicted to enter the automobile markets in increasing numbers in the near future. This paper investigates 2 aspects relevant to the promotion of hybrid vehicles as part of an energy reduction strategy. First, are hybrid cars accompanied by rebound effects, which counteract their increased fuel efficiency? Second, do tax rebates indeed lead to higher sales numbers? We present results from a survey conducted with all 367 buyers of hybrid second-generation Toyota Prius in Switzerland in the first 9 months after market entry (response rate, 82.6%). As control group, questionnaires were also sent to 250 Toyota Corolla (61% returned) and 250 Toyota Avensis (52%) buyers. Among other items, the surveys asked for the car being replaced, if any. Main results are that the increase in car size for hybrid car buyers was lower than both, the market trend and the control group. Increase in car size was lower for hybrid car buyers than for both control group and market trend. 6% of hybrid car purchases did not replace a previously owned vehicle (control group 3%, P =0.05), the Swiss market average being 20%. Hence rebound effects could be identified neither for vehicle size nor for vehicle ownership. As an energy policy measure, hybrid vehicles are eligible for tax rebates in parts of Switzerland. We found evidence that these tax rebates indeed lead to significant higher sales. We present a rough cost estimate of such tax rebates as CO2 abatement policy tool. [Copyright &y& Elsevier]

Abstract: This research examines the observed steering wheel hand positions and the reported steering wheel hand placements of a sample of Sports Utility Vehicle (SUV) and car drivers. Following the method of Walton and Thomas (Walton, D. & Thomas, J. A. (2005). Naturalistic observations of driver hand positions. Transportation Research Part F. Traffic Psychology and Behaviour, 8, 229–238), variation in hand position is found to be an effective, indirect measure of drivers’ perceived risk. As perceived risk increases, it is expected that drivers will be more likely to adopt a ‘10–2 o’clock’ hand placement to increase their control over the vehicle. Because they are a larger vehicle, SUVs are typically perceived by drivers as being safe, so it is also expected that SUV drivers would have a lower level of perceived risk, as evidenced by their hand positions. A questionnaire examining drivers’ hand placements confirmed that drivers do perceive that two hands on the top half of the steering wheel will give the most control over the vehicle, and also revealed that drivers overestimate their use of this hand position, when compared with actual observation. Observed hand positions reveal that SUV drivers are more likely to drive with one hand instead of two hands on the top half of the steering wheel, indicating a lower level of perceived risk. [Copyright &y& Elsevier]

Abstract: Hybrid powertrains are considered being a promising technology to decrease fuel consumption of passenger cars. Sales numbers of hybrid cars are expected to rise considerably until 2010. However, the introduction of more efficient products is often accompanied by rebound effects, which counteract the positive effect of increased efficiency. We investigate two kinds of direct rebound effects that could possibly occur when buying hybrid cars: (i) people could tend to switch from small and/or already fuel-efficient cars to the new hybrid car, and (ii) the average vehicle ownership could increase, if the hybrid car is often purchased without disposing of an already owned vehicle. A survey was conducted with all 367 buyers of the Toyota Prius 2 in Switzerland in the first nine months after market entry. Return rate reached 82.6% without sending out reminders. The survey-based approach does not allow us to investigate whether hybrid drivers will in the future drive more (the classical example of the direct rebound effect). Detailed data on the car replaced by the Prius and on the other cars owned by the household were collected. Our analysis shows that average CO2 emissions dropped from 210 g/km for the previously owned vehicles to 104 g for the Prius. Empty vehicle weight (curb weight) increased by 9 kg only, which is below the market trend. A constant population-averaged vehicle ownership still allows for a certain amount of first-time car purchases and for increasing vehicle ownership for individual households, as these additional cars are compensated for by other households disposing of a vehicle. We present a new vehicle ownership model which assesses whether the vehicle transaction behavior of a sample of new car buyers corresponds, on average, to constant or increasing vehicle ownership. It is based on disaggregated data from the Swiss travel behavior micro census. Model results are consistent with market data and data from literature. Model results show that if ca. 20% of car purchases do not replace a vehicle (for a population with an age distribution identical to Prius buyers), this still allows for constant average household vehicle ownership. Only 13.7% of the surveyed Prius buyers did not replace an old car. Hence neither of the two rebound effects investigated could be found though the sample would have been large enough to do so: vehicle size did not increase, nor did average household vehicle ownership. [Copyright &y& Elsevier]

Given the difference between peak and off-peak occupancy rates in public transport, the average emission per traveller kilometre is lower in the peak than during the off-peak period. However, in this paper it is argued that it is much more fruitful to analyse environmental effects in marginal than in average terms. The issue appears to depend on capacity management policies of public transport suppliers that are facing increases in demand both during the peak and off-peak period. A detailed analysis of capacity management of the Netherlands Railways reveals that the off-peak capacity supply is mainly dictated by the demand levels during the peak period. Topics that receive attention in the analysis are the effects of frequency increases and size of vehicle increases on environmental effects. Also environmental economies of vehicle size are taken into account in the analysis. The main conclusion is that the marginal environmental burden during the peak is much higher than is usually thought, whereas it is almost zero at the off-peak period. Thus, one arrives at a pattern that is entirely reversed compared with the average environmental burden: peak passengers are more polluting than off-peak passengers. The conclusion is that policies based on average environmental performances would lead to misleading conclusions. [Copyright &y& Elsevier]