VISUALIZING TRANSPORT FUTURES THE POTENTIAL OF INTEGRATING PROCEDURAL 3D MODELLING AND TRAFFIC MICRO-SIMULATION IN VIRTUAL REALITY APPLICATIONS

Alexander Erath, Tanvi Maheshwari, Michael Joos, Jonas Kupferschmid, Michael van EggermondFuture Cities Laboratory, Singapore ETH CentreCorresponding author: erath@ivt.baug.ethz.ch

Paper No. 17-06628

BACKGROUNDVisualizations play an important role in transportation planning to communicate plans and policies that support active transport modes. Since adding infrastructure often means a large public investment or a trade-off for space with other transport modes, visualizations are often used in early stages to illus-trate the gains of a project with regards to traffic safety, liveability or social inclusion. They are also used in research application to study the impact of such infrastructure on people’s behaviour and quan-tify user reactions towards infrastructure that does not exist today.

VR IN TRANSPORT PLANNINGSo far, visualizations to communicate future street designs rely heavily on pictures, photo-montages, maps or simulation videos. Recent and ongoing technological development in the field of Virtual Reality (VR) opens new windows for practical applications and scientific insights by allowing the user to im-merse in the future environment. What are the potential use cases of Virtual Reality in transportation research and planning?

STATED PREFERENCE SURVEYThe opening of new infrastructure can open windows of opportunity for longitudinal studies to assess impact of built environment on mode choice. However, experimental variation is limited to how the new infrastructure has actually been built. Revealed preference studies can overcome some of those problems, but the validity of the findings is always restricted to features of the built environment that already exist. Recent advances in computer graphics and lowered barriers to entry into the field of gaming has opened new opportunities to generate realistic 3D scenarios that are suitable for behav-ioural studies.

BEHAVIOURAL EXPERIMENTSWalking and cycling is a multi-sensory experience which includes vision, auditory, somatic sensation, olfactory and vestibular sensory stimulation. Conducting surveys to understand the perception of vari-ous street design options based on static pictures only can be too restrictive. Using Virtual Environ-ments (VE) is a well-established methodology in the field of cognitive psychology. Although there are several limitations in VE, such as lower resolution, less realism and often no auditory, tactile, proprio-ceptive and vestibular cues, VE experiments have successfully been conducted in various fields of cog-nitive studies.

DRIVING SIMULATORDriving simulators have been used in transport research since the 1960’s to study driver behaviour and her/his interaction with the vehicle and the road. Recently, a few research groups also developed cycling simulators for applications in the areas of road safety and traffic education. Using consumer-grade head-mounted displays as part of a cycling simulation setup lead to a substantially enhanced visual im-mersion and allowed new applications for research, for example to study the perception and measure physical reactions that different street design and traffic operation scenarios trigger.

COMMUNICATION AND PUBLIC ENGAGEMENTA common virtual reality application for architectural design and urban planning purposes is to display detailed 3D CAD models of architectural spaces and visualization of large datasets in a photo-realistic fashion. The application has mostly been limited to presentation, recreation, and educational purposes. The development of VR as a design and engagement tool raises quite different demands. A simplified design model, which is capable of handling details in a different way may be sufficient to garner feed-back in a public engagement or collaborative design process.

INPUTIntegration in Game Engine

Images

OUTPUT

Virtual EnvironmentModelling StreetsProcedural ModellingESRI City Engine is a 3D modelling software ap-plication developed by ESRI R&D Centre Zurich, that uses a ‘procedural’ approach. For this re-search, the ESRI’s ‘Complete Streets’ rule file was used. It incorporates various sources of transportation planning knowledge including NACTO, AASHTO and MUTCD standards. The goal of the rule is to represent a diversity of street configurations to support multi-modal planning in urban areas.

Geometric ModellingProcedural modelling allows a degree of proto-typing that saves significant amount of time usu-ally spent on hand-crafting geometric models. But this method poses several limitations. Mod-elling unique non-repeating conditions proce-durally takes a disproportionate amount of time. Therefore we supplement procedural modelling with geometric modelling for unique cases.

Modelling TrafficTraffic microsimulations simulate the behaviour of vehicles, cyclists and pedestrians. For this re-search project we used PTV Vissim as it offers the widest range of urban traffic simulation ca-pabilities. It is mainly designed to quantitatively evaluate traffic scenarios with regards to vehicle and pedestrian densities, road and intersection capacities, as well as travel times or delays. Rep-resenting cyclists in shared spaces can be chal-lenging and we are developing models to simu-late such situations.

To explore the potential of integrating of Virtual Reality applications for transportation research and planning, we propose a software pipeline that integrate ESRI City Engine (procedural 3D modelling), 3DS Max (geometric modelling) PTV Vissim (traffic microsimulation) in Unity (game engine) supporting versatile output formats and applications.We chose to use Unity to combine both, interact with the environment and present that experi-ence on a VR head-mounted-display (HMD), be-cause of its visual capabilities, VR support, ample range of file formats and ease of use.In this pipeline design data only flows from City Engine/Vissim to Unity. To achieve a truly inter-active experience we have to close the pipeline loop and feed user activity in Unity back to the beginning of the pipeline. This interaction loop is still in experimental phase, and since both pro-grams demand high levels of CPU usage.

THE PIPELINE

Videos

CONCLUSION AND OUTLOOKCASE STUDY FUTURE CASE STUDIES

AcknowledgementsResearch conducted at the Future Cities Laboratory is co-funded by the Singaporean National Research Fund and the ETH Zurich, located at the Campus for Research Excellence And Technological Enterprise (CREATE).

In any field of application, it will be important to clearly demonstrate how VR applications can fill existing methodological gaps or lead to more ef-fective and efficient study designs. It will be im-portant to conduct qualitative studies to under-stand the added value of VR and identify the rele-vant factors related to the perception and reten-tion value of VR, as we proposed with the Park(ing) Day case study.

We also see much potential for the use of VR in research beyond the presented case studies. For example, VR-based interactive serious games could help us understand the dynamics and de-terminants of travel behaviour better. Percep-tions and reactions to changes in infrastructure and the behaviour of other road users could be studied in controlled experiments. Furthermore, with VR we can also experience the perspective of other road users.

As immersive virtual environments become a more accessible technology, the potential appli-cations are fast expanding beyond traditional gaming industries. Transportation planning, as we have illustrated, is one such domain. While real experiences can never be entirely replicated, like other conventional methods of communica-tion, VR is an additional tool, with evident added value, and particular limitations. These limita-tions are yet to be clearly understood, defined and quantified. The case studies presented in this paper, help to further clarify the applications and limitations in this regard.

3D MODEL

TRAFFIC SIMULATION

GAME ENGINE

IMAGES

VIDEOS

VIRTUAL ENVIRONMENT

0

20

40

60

80

100

As it is today New design

NO

NO

YES

YES

0

20

40

60

80

100

As it is today New design

NO

YES

YES

NO

Using the Complete Street Rule we can automat-ically generate numerous 3D models of streets in different design configuration quickly. To lever-age this capability, we developed an experimen-tal design for a stated preference survey employ-ing a set of variables with related attribute levels as listed in the table below.

We generated 200 choice renderings of street design scenarios with the camera positioned at eye-level of a cyclists, which we will use in a qualitative, exploratory pilot study to better un-derstand which differences between the two ren-derings are visible for participants. Depending on the outcome, we will refine the experimental design, either by limiting the number of consid-ered variables or including further constraints.

An integration of PTV Vissim and Unity through a real-time interface can provide the fundament for implementing a VR cycling simulator. Mul-ti-user settings also offer interesting field of ap-plications that for example researchers interest-ed in studying the behaviour in evacuation sce-narios have tested recently.

Bike Pulse

Variable Attribute LevelNumber of car lanes in one direction

Road traffic circulation

1, 2, 3, 4

One-way, bidirectional

Location of cycling facility Mixed on sidewalk, dedicated lane, mixed with traffic

Walkway width 1.5, 2.5, 3.5 Meters

Motorized lane width 2.7, 3.1, 3.4 Meters

Speed limit (indicated with signs and level of motion blur)

30 Km/h, 50 km/h, 80 km/h

Availability of dedicated bus lane Binary

Position of bus lane Left most lane, right most lane (scenario is based on left-hand traffic

Cycling lane type No dedicated lane, one-way on road, two-way on road, one-way between sidewalk and road, two-way between sidewalk and road, between sidewalk and buildings.

Cycling lane width 0.8, 1.5, 2.5, 0 (for cases without dedicated lane), all in Mt

Type of buffer between cycling lane and motorized lane

Painted stripe, curb bugger, curb with plant-ings, curb with trees, spaced curb, tubular markers, shoulder, fence, none

Buffer width 0.1, 0.8, 1.5, 0 (for cases without buffer)

Bike lane colour Blue, green, red, paver, black

Width of planting stripe towards sidewalk 0, 0.5, 1 MeterPresence of covered walkway Binary

Density of cars 50, 125, 200 Cars per km and lane

Density of buses 8, 15, 20 per km and lane

Density of pedestrians 10, 20, 40 Percent of sidewalk area

Density of cyclists 60, 150, 300 Cyclists per km and lane

Bike to the FutureIn order to understand what would make Singa-pore more walkable and cyclable – and given the low popularity of cycling in Singapore - we used VR to make people understand better the impact of new design and planning interventions. On PARK(ing) Day, 2016, a parking lot in Tiong Bahru neighbourhood showcased what Seng Poh Road might be like in the future if it is de-signed for slow traffic - pedestrians and cyclists.

The exhibit was used to conduct an experiment to understand the added value of VR as a communi-cation tool. To study the perception and retention value of VR, a pre-experiment survey determined the participant’s current travel behaviour. Fol-lowing which, the participants were asked that given the improved design, how would their mo-bility behaviour and attitude be influenced. Second, the participants were asked what they ‘liked’ and ‘disliked’ about the new design, to deduce what they retain from the experience.

Would you cycle on Seng Poh Road? Would you cycle on Seng Poh Rd with a 10yr old?

9

10

Generating streets and lots procedurally on ESRI City Engine1

Street as is (left) and model created on 3DS Max geometrically (right)

Visuals of simulated model from Unity.

Schematic representation of software pipeline developed for experiment.

Micro-simulation in PTV Vissim in plan VR model of Seng Poh Road as is (left) and with modified design (right)Hundreds of images generated from cyclist’s eye level on Unity3D model and heat map of traffic micro-simulation generated in Unity.

Bicycle Simulator

Attributes and attribute levels as input for the stated preference design

Exploring Streets of Tiong Bahru in Virtual Reality

Snapshots of Virtual Environments created in Unity

Survey Results from 95 samples

Bike to the Future setup with Tiong Bahru Market in background

MP4 video of VR model of Tiong Bahru Market (left) and 360 degree video of VR model of Tiong Bahru (right)

Bike to the Future on World Park(ing) Day, September 16, 2016

2

3

4

5

6

7

8 11

12

13

14

15