The importance of value of time studies a dutch perspective

The 2013 national Dutch value of time study Gerard de Jong – Significance and ITS Leeds 29 October 2015 and reliability The 2013 national Dutch value of time study Gerard de Jong – Significance and ITS Leeds 29 October 2015 Contents What’s the question? Data collection: I II The 2009 SP data: internet panel The 2011 SP data: en-route recruitment Model estimation Impact of recruitment method The recommended values A fair comparison of the 1997 and 2009/2011 VTT Why we need a VTT?  In many countries, transport projects (e.g new road or railway line) are evaluated ex ante using cost-benefit analysis (CBA)  In CBA project effects are expressed in money units  Costs include construction, maintenance and external cost  Main benefit often is travel time saved □ There could also be journey time reliability benefits (often still ignored)  This is in hours or minutes, so we need a conversion factor to money □ This factor is called the value of travel time VTT (e.g in euros per hour) The context: CBA of transport projects Costs Benefits Construction costs Time benefits: Pt*Qt Pt: Value of travel time VTT Qt: from transport model Change in maintenance costs Reliability benefits: Pr*Qr Change in external costs Other transport cost savings Pr: Value of travel time variability VTTV Qr: forecasting model or surcharge From transport model … … … … The new national study  The objective of this project, for the Dutch Ministry of Infrastructure and the Environment, was: to provide values of time (update) and travel time reliability (first Dutch empiricallybased values) for passenger and freight transport by mode that can be used in costbenefit analysis (CBA) of transport projects  The project was completed and the report was officially released in June 2013) (weblink at the end); the values are now official: used in all national transport projects  In The Netherlands the VTT and VTTV are specifically for use in CBA, not for inputs into transport forecasting models  The Netherlands also had national VTT studies (passengers) in 1988-1990 and 1997-1998 What’s the question?  This presentation is about the passenger transport component of the study  Values of time (VTTS) in passenger transport nowadays mainly come from Stated Preference (SP) surveys (see international meta-analysis by Wardman et al., 2012)  Different interview methods: □ □ □ □ Mailback (pen and paper/cards) CAPI (used for freight transport) CATI Internet Recruitment method: − Project-specific recruitment (e.g en-route) − From existing internet panel Initial choice of interview and recruitment method (2009 data)  The SP surveys required considerable customisation □ Mailback can only provide this through extensive two-step procedures  CAPI and CATI were considered too expensive for a large survey (labour cost)  Initial choice: internet survey using an existing internet panel 2009 survey procedure (1)  5,760 members of an existing on-line panel were interviewed using computerised stated preference interviews in November 2009  Specific target numbers of interviews were set (and reached) for different segments: □ □ □ □ Transport mode used (car, train/metro, bus/tram, airplane and recreational navigation) Travel purpose (commuting, business, other) Time-of-day (peak, off-peak) Presence of transfers (public transport only)  All respondents were asked which modes they had used in the past three months, etc □ This was used to allocate respondents to questionnaires for specific segments 2009 survey procedure (2)  All respondents were drawn from the largest on-line panel of The Netherlands (240.000 participants)  The survey could be started by clicking on a weblink  The members received a reward for successfully completing the interview (equivalent to €1.50)  The interviews on average took 20 minutes 10 The final VTT results are based on a combination of the 2009 and 2011 data  The base VTT and VTTV levels come from estimates on the 2011 data  Socio-economic interaction effects and the effect of the base time and cost levels as well as of changes in time and cost offered in the SP are estimated on 2009 and 2011  Also: latent class models used here, and expansion of the estimation results to the population (in hours travelled) using the 2010 national travel survey (OViN)  This yields the recommended values for use in CBA 25 Recommended VTTs in euros per person per hour   Commute Car Train Bus,  tram,  metro 9.25 11.50 7.75 All  surface  modes Air Recr. navigation 9.75     Business employee 12.75 15.50 10.50 13.50 85.75   Business employer 13.50 4.25 8.50 10.50 -   Business  26.25 19.75 19.00 24.00 85.75   Other 7.50 7.00 6.00 7.00 47.00 8.25 All purposes 9.00 9.25 6.75 8.75 51.75 8.25 Note: all values are rounded off to the nearest multiple of € 0.25 26 Recommended reliability ratios  Reliability ratio (RR) = value of standard deviation of travel time/VTT  Car, train, bus, tram and metro: □ □ □ Commuting 0.4 Business 1.1 Other 0.6  Air: □ □ Business 0.7 Other 0.7 27 It’s just not fair! 28 It’s just not fair!  Fair comparison: comparing like with like  Otherwise conclusions will be incorrect: Not based on real differences but on differences in methodology 29 The seven differences (methodological) 1997 2009/2011 Interactions with cost and time Interactions with VTT Cost and time terms Linear Linear & non-linear Dependence of VTT on travel time itself No Yes Socio-economic interaction factors No education Different set, including education Expansion procedure Weights per segment Sample enumeration OVG 1995 OViN 2010 MNL panel latent class Estimation space Expansion totals Type of model  Therefore the VTT in the 1998 report and the 2013 report cannot be compared 30 Expected changes 1997-2010  Consumer prices rose by 32% -> VTT +32%  Real income (over and above the price change) went up by 30% The Dutch guidelines adopted an income elasticity of the VTT of 0.5 -> VTT +15%  More congestion, more crowded trains, lower compensation of cost, crisis  New ICT has become much more common in this period: □ □ Mobiles (including handsfree, car kit), smartphones, iPads, laptops Easier to use travel time in a more productive/enjoyable way -> VTT ↓  In the period 1988-1997 VTT did not change much: □ Gunn (2001): effect of real income growth more or less balanced by the technology effects 31 Methodology to obtain a fair comparison  Applying the 1997 methods on the 2009/2011 data is not so interesting (no benefits from methodological improvements)  So we redid the analysis of the 1997 data using the 2009/2011 methods  We did this re-analysis step-by-step to see the impact of each of the seven differences (similar steps for the analysis of 2009/2011 data)  This gives two results: □ □ Which VTT would we have obtained in the nineties if we could had used modern methods (and future population data)? The real evolution of VTT by mode and purpose between 1997 and 2009/2011 32 Detailed comparison for commute 33 Outcomes: impact of methodological differences on 1997 or 2009/2011 VTT 1997 2009/2011 VTT Interactions with cost and time Interactions with VTT −4% Cost and time terms Linear Linear & non-linear 0% Dependence of VTT on travel time itself No Yes −2% Socio-economic interaction factors No education Different set, including education +1% Expansion procedure Weights per segment Sample enumeration +4% Differs by mode OVG 1995 OViN 2010 0% Differs by mode MNL panel latent class Estimation space Expansion totals Type of model Differs by mode 34 Outcomes: impact of methodological differences on 1997 or 2009/2011 VTT 1997 2009/2011 VTT Interactions with cost and time Interactions with VTT −4% Cost and time terms Linear Linear & non-linear 0% Dependence of VTT on travel time itself No Yes −2% Socio-economic interaction factors No education Different set, including education +1% Expansion procedure Weights per segment Sample enumeration +4% Differs by mode OVG 1995 OViN 2010 0% Differs by mode +31% General range: 20-40% Estimation space Expansion totals Type of model MNL panel latent class Differs by mode  Unobserved heterogeneity leads to a large downward bias in the VTT 35 Fair comparison 1997 – 2010 (no inflation correction; comparison of p-LC models) Car Train Bus, tram, metro Commute +13% +49% +9% +23% Business +13% +60% +98% +26% Other +71% +59% +52% +65%   All surface modes 36 Discussion of results of the comparison  All VTTs by mode and purpose have increased  Overall, the increase is slightly below the expected increase of +47% □ □ small overall impact of ICT changes? Income elasticity of 0.5 seems about right?  Relatively small changes for commute and business: ICT developments more important than for other travel?  Relatively small increases for car (relative to train): □ □ important ICT developments for train had already entered the market in 1997? trains more crowded than in 1997? 37 What we conclude?  Beware of internet panels in VTT research!  Allowing for unobserved heterogeneity (using a panel Latent Class model) increases VTT considerably □ Much more than the other six differences  In the period 1997-2009/2011 the average VTT went up by about price change plus 0.5 times the real income change □ But differences between purposes and modes that could be related to ICT developments 38 For more information email: dejong@significance.nl or g.c.dejong@its.leeds.ac.uk Final report and papers: http:// www.kimnet.nl/sites/kimnet.nl/files/filemanager/bijlagen/Bijlage_Value_of_time_and_ reliability_in_passenger_and_freight_transport_in_the_Netherlands_reprint.pdf Kouwenhoven, M., G.C de Jong, P Koster, V.A.C van den Berg, E.T Verhoef, J.J Bates and P Warffemius (2014) New values of time and reliability in passenger transport in The Netherlands, Research in Transportation Economics, 47, 37-49 Jong, G.C de, M Kouwenhoven, J Bates, P Koster, E Verhoef L Tavasszy en P Warffemius (2014) New SP-values of time and reliability for freight transport in the Netherlands, Transportation Research Part E, 64, 71-87 39 [...]... 1988/1990 and 1997/1998, □ □ which have always been regarded as very plausible by the various transport sectors, and are not considered to be particularly high in an international perspective  Our conclusion is that the most likely explanation is that the 2011 values are correct and that the 2009 values are biased downwards 24 The final VTT results are based on a combination of the 2009 and 2011 data  The. .. each segment (socio-economic, trip purpose, trip length, mode), the respondents that participate in such an online panel (which takes time, for a rather low monetary reward) might have a lower VOT than a nonparticipant  This is a self-selection problem  Even after expansion, the resulting values of time would then be lower than the true values of time  To investigate this hypothesis, another data... sample changes in the statistical design of the SP Including reliability in the SP Increased use of mobile phones, smartphones Impact of economic crisis Increase in congestion  These only explained part of the differences with the official values 13 But there could be another explanation …  The sample of respondents obtained from this internet panel might be biased with respect to their value of time. .. data  The base VTT and VTTV levels come from estimates on the 2011 data  Socio-economic interaction effects and the effect of the base time and cost levels as well as of changes in time and cost offered in the SP are estimated on 2009 and 2011  Also: latent class models used here, and expansion of the estimation results to the population (in hours travelled) using the 2010 national travel survey...Example of an SP choice screen (exp 1) 11 Example of an SP choice screen (exp 2a) 12 Initial results (2009 data)  VOTs implausibly low □ □ About € 4 per hour for car and public transport Substantially lower than the official values (about € 9 per hour) and the international literature  Checked for possible explanations: □ □ □ □ □ □ □ socio-economic composition of sample travel time distribution of. .. set was collected in the first half of 2011 14 The 2011 SP data: en-route recruitment  Almost 1500 respondents recruited at petrol stations, parking garages, train stations, bus stops, airports and ports  This is the same recruitment method as in earlier national value of time surveys of 1988/1990 and 1997/1998  Persons willing to participate were asked to answer an internet questionnaire on the. .. 51.75 8.25 Note: all values are rounded off to the nearest multiple of € 0.25 26 Recommended reliability ratios  Reliability ratio (RR) = value of standard deviation of travel time/ VTT  Car, train, bus, tram and metro: □ □ □ Commuting 0.4 Business 1.1 Other 0.6  Air: □ □ Business 0.7 Other 0.7 27 It’s just not fair! 28 It’s just not fair!  Fair comparison: comparing like with like  Otherwise conclusions... Discussion of results: does it matter/help? (1)  Especially for commuting (car, train, bus, tram, metro): significant lower values for panel members, □ even after correcting for the different distributions for the travel time and travel cost, and after inclusion of the socio-economic interactions  Similar findings for the business and for airplane segment  Other purposes and recreational navigation:... navigation: no significant difference between panel and non-panel  We conclude that in the 2009 survey there was a bias towards low-VTT persons, who are willing to give up time to participate in an internet panel and to fill out web questionnaires for a rather small reward 23 Discussion of results: does it matter/help? (2)  The resulting VTTs from the 2011 survey are much more in line with the values found...  Applying the 1997 methods on the 2009/2011 data is not so interesting (no benefits from methodological improvements)  So we redid the analysis of the 1997 data using the 2009/2011 methods  We did this re-analysis step-by-step to see the impact of each of the seven differences (similar steps for the analysis of 2009/2011 data)  This gives two results: □ □ Which VTT would we have obtained in the ... international perspective  Our conclusion is that the most likely explanation is that the 2011 values are correct and that the 2009 values are biased downwards 24 The final VTT results are based...  The project was completed and the report was officially released in June 2013) (weblink at the end); the values are now official: used in all national transport projects  In The Netherlands... (car, train/metro, bus/tram, airplane and recreational navigation) Travel purpose (commuting, business, other) Time -of- day (peak, off-peak) Presence of transfers (public transport only)  All