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CVEN4405: Human Factors in Civil and Transport Engineering

Human Performance Limitations and Traffic Engineering 2:

Perception and Expectancy Term 3, 2020

Week 5, Lecture 1a

1

CVEN 4405 Human Factors in Civil and Transport Engineering

Term 3 2020 Week 5 - Lecture1a

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Lecture Recordings

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3

Welcome Back!

4

Course Coordinator and Lecturer

Prof. Michael Regan, PhD Professor of Human Factors

Research Centre for Integrated Transport Innovation (rCITI) School of Civil and Environmental Engineering

University of NSW Sydney

T: +61 (0)2 9385 9504 E: [email protected]

Staff Webpage

5

The CVEN 4405 Teaching Team

Coordinator and Lecturer Prof. Michael Regan Professor of Human Factors Research Centre for Integrated Transport, UNSW Sydney E: [email protected]

Teaching Fellow Dr Prasannah Prabhakharan Research Fellow Research Centre for Integrated Transport, UNSW Sydney E: [email protected]

Demonstrator Mitch Cunningham E: [email protected]

6

Review of Last Lecture

• Vision and driving

• The Visual field and driving

• Eye and Head Movement

• Conspicuity

• Legibility

• Visual disabilities

• Illumination

• Changing Illumination

• Glare

• Visual performance and accident rates

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This lecture - Overview

• Perception and Traffic Engineering • Expectancy and Traffic Engineering

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Learning Outcomes

CLO1: Explain the fundamental principles of HF that can be used by civil and transport engineers to facilitate user- centred design

CLO2: Apply HF principles, methods and data to the design of road and traffic management systems

CLO3: Plan for the integration of HF into the design lifecycle of the road and traffic management system

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Wickens’ Model of Human Information Processing - Figure

Source: Source: Adapted from Wickens (1992), p. 17

Perception and Traffic Engineering

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Perception and Traffic Engineering

– In Week 1 (Lecture 2) we talked about Perception in Wickens’ (1986) model of human information processing.

– Once information has been sensed, higher centres in the brain interpret and attach meaning to it. This is the process of perception.

– We noted a few things about Perception (next slides)

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Perception – Different Perceptions

The same sensory information can give rise to different perceptions in different people.

 So, information displayed on traffic control devices should be unambiguous, to elicit the same perception in everyone.

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Perception – Learned Associations

• Our perceptions are heavily influenced by past experience, learned associations and expectations.

 So, traffic engineers should capitalise on these learned associations in designing traffic control and other devices e.g. green = go; red = stop; reading text from top to bottom; etc

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Perception – Eliciting Correct Meaning

Traffic engineers should make the most of design features that help road users correctly perceive the meaning of information displayed on traffic control devices.

e.g. So, use symbols that people are regularly exposed to (e.g. on phone apps) and instantly understand.

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Perception – Distorted Perceptions

• Our perceptions can be distorted. • So, traffic engineers can take advantage of this by deliberately distorting

the perceptions of road users in ways that modify their behaviour in ways that improve the safety and efficiency of the road network.

 e.g. 2-D and 3-D Perceptual Countermeasures.

Relevance and Importance

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Perception – Relevance and Importance (1)

Drivers must perceive the relevance and importance of a signal (e.g. traffic sign). If not, the signal will be ignored by the driver or road user.

As discussed in the last lecture, even conspicuous traffic signs will be ignored if they are considered irrelevant to the driver.

Most traffic signals confronted by drivers during a trip are ignored because they (correctly) are not perceived as being relevant or important.

So, signals provided by traffics engineers which are important should be presented in a way that ensures that the driver appreciates their relevance and importance.

Source: Ogden, 1996, p 2.1.14

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Perception – Relevance and Importance (2) • It is particularly important to ensure that the driver

perceives a traffic signal as affecting his or her own well- being.

• Designing traffic signs and signals that are of a standard shape and colour, with a recognisable legend and/or symbol, will ensure that the sign/signal is perceived by drivers as relevant and important.

Source: Ogden, 1996, p 2.1.14

Comprehensibility

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Perception – Comprehensibility (1) • Messages on some types of traffic signs, especially warning and

regulatory signs, may be presented either symbolically or in written form (as text).

• There is some evidence that driver reaction times are shorter for symbolic signs than for corresponding signs presented in written form.

• Symbolic signs also tend to be more legible and conspicuous due to the larger sign elements they contain (Cole and Jenkins, 1982; cited in Ogden, 1996).

• Well-designed symbolic signs are quicker and easier to comprehend than their corresponding signs in written form. However, both tend to be retained equally well in working memory (Lay, 1986, p 429; Donald, 1995; cited in Ogden, 1996).

Source: Ogden 1996, p. 2.1.14

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Perception – Comprehensibility (2) • A lot of the information conveyed by traffic engineers to the

driving public is not well understood (Cairney, 1984; cited in Ogden, 1996).

• Consequently, only standard signs, messages, formats, etc should be used by traffic engineers, and last weeks’ tutorial introduced you to some of the main standards and guidelines on this topic.

• Unconventional treatments that involve the use of home made signs and formats are unlikely to be comprehensible to most drivers and should be avoided.

Source: Ogden 1996, p. 2.1.14

Credibility

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Perception – Credibility (1) • Credibility refers to the extent to which a driver perceives

that a signal is true and refers to them.

• The credibility of a traffic signal is affected by the context of the signal, how it is used in other contexts, and how it is used in relation to other traffic control devices.

• Traffic engineers can optimise credibility by ensuring that the use and application of traffic control devices (especially signs) accords with current practice as set out in the relevant national guidelines, codes and standards.

Source: Ogden 1996, p. 2.1.15

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Perception – Credibility (2) Ogden (1996) makes several design recommendations for enhancing credibility:

• ensure that the sign or device is credible in its context • ensure that sign selection, colour, and shape conform with

national codes, guidelines and standards • avoid unnecessary use of signs and other traffic control

devices • avoid use of unnecessarily restrictive signs

• e.g. the over-use of STOP signs detracts from their credibility at sites where it really is important that vehicles come to a standstill – consider GIVE WAY signs instead

Source: Ogden 1996, p. 2.1.15

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Perception – Credibility (3) • important messages should be adequately displayed (e.g.

speed limit repeater signs should be used; advance direction signing should be consistent and prominent)

• speeds on advisory signs should be realistic and consistent

• assist the driver to distinguish between important and relatively unimportant information by consistent use and avoidance of poor practice

• e,g. poor practice may involve removal or replacement of signs or devices currently in place.

Source: Ogden 1996, p. 2.1.16

Speed Perception

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Perception – Speed perception and choice (1)

• Speed is a significant contributing factor to road fatalities and injuries, which increases crash risk and crash severity

• Both speed perception and the speed choice of road users are important Human Factors issues in road and traffic design.

Source: Cunningham, Regan & Cairney, 2017, p. 44

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Perception – Speed Perception and choice

• Speed perception refers to a road user’s perception or judgement of how fast he or she is traveling.

• Speed perception may be based on: • direct information e.g.from speedometer • indirect information e.g. from engine noise, road

vibration, visual environmental cues

Source: Campbell et al., 2012; cited in Cunningham et al, 2017, p. 44

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Perception – Speed perception and choice (2)

• Visual environmental cues are believed to be a primary source of information for speed perception (Edquist et al., 2009; Campbell et al., 2012)

• Drivers perceive speed from the visual environment based on information (stimuli) along the roadside (mostly in peripheral vision) which, when driven past, creates optic flow (Martens et al., 1997; Edquist et al., 2009).

Source: Cited in Cunningham, Regan and Cairney, 2017, p. 44

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Perception and Driving: Speed Perception & Choice - Theory

Example of optic flow which could inform speed perception

Source: CNS Vision Lab, n.d.; featured in Campbell et al., (2012); cited by Cunningham, Regan & Cairney (2017), p. 45

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Theory – Speed perception and choice (2) • Increased optic flow (previous slide) tends to make

drivers overestimate their speed (they perceive they are travelling faster than they really are).

• This, in turn, can lead to a reduction in vehicle speed (Martens et al., 1997; Edquist et al., 2009).

• Conversely, roads with open fields and no prominent side features have few stimuli to produce optic flow; in which case speeds are likely to be underestimated.

Source: Cited in Cunningham, Regan and Cairney, 2017, p. 44

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Perception – Speed perception and choice (3)

• The presence of trees or buildings can reduce this effect, allowing drivers to better calibrate their perception of speed (Edquist et al., 2009).

• The distance at which such roadside objects are set back from the road may impact speed perception and choice.

• Roadside objects set further back from the road are associated with higher speed choice (Edquist et al., 2009).

Source: Cited in Cunningham, Regan and Cairney, 2017, p. 44

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Perception – Speed Perception and Choice (4)• Various individual characteristics also influence speed

perception and choice e.g.:

• age • gender • thrill-seeking tendencies • mood • intoxication and • inattention

• Generally, these are beyond the control of road and traffic engineers.

Source: Cunningham, Regan and Cairney, 2017, p. 44

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Perception – Speed Perception and Choice (5)

• Generally, if drivers underestimate their travel speed, they will drive faster than they intend

• Generally, if drivers overestimate their travel speed, they will drive more slowly than they intend

Source: Martens et al., 1997; Edquist et al., 2009; cited in Cunningham, Regan and Cairney, 2017, p. 45

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Design guidance – Speed Perception and Choice (6)

• Roads need to be designed to promote concordance between the driver’s perception of speed and the posted speed limit.

• There needs to be consistency between the roadway cues which mediate speed perception and the posted speed limits.

Source: Cunningham, Regan and Cairney, 2017, p. 45

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Design guidance – Speed Perception and Choice (7) The following road design factors are likely to cause drivers to underestimate their travel speed, and hence travel faster (Campbell et al., 2012):

• higher road design standard • greater roadway width • divided, walled urban roads • rural roads without roadside trees or other objects • daylight compared to night-time illumination

conditions.

Source: Cunningham, Regan and Cairney, 2017, p. 46

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Design guidance – Speed Perception and Choice (8)

The following road design features are likely to cause drivers to overestimate their travel speed, and hence travel slower (Campbell et al., 2012):

• two-lane narrow urban roads • roads enriched with roadside objects (e.g. densely

lined on the sides with trees) • perceptual countermeasures such as transverse

pavement markings.

Source: Cunningham, Regan and Cairney, 2017, p. 46

Topic 2: Expectancy and Traffic Engineering

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Expectancy (1)

Our perceptions of the road and traffic environment are heavily influenced by our expectations.

The role of “expectancy” is critical in driver perception of the road and traffic environment

People perceive and respond quickly to things that they expect but respond slowly to things that are unexpected

People tend to perceive events that accord with their expectations and overlook events that that are not in line with their expectations

Source: Theewes & Hagenzieker, (1993); cited in Wickens et al., 2004; Theeuwes (2002), p.131

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Expectancy (2)

Expectancies reduce reaction times because drivers respond through familiarity and habit

Typically, road accidents happen because drivers don’t expect particular events to happen and do not adequately anticipate them

• Discussion: Has anyone had an accident or incident because someone or something violated their expectations?

Source: Ogden (1996); Malaterre (1986); Theeuwes (2002); Fuller & Santos (2002); Wickens et al., (2004)

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Expectancy (3)

Around 60% of all road accidents occur because of inappropriate expectations or interpretations of the environment

User-Centred Design should capitalise on expectancy, while at the same time communicate unexpected situations to drivers that might endanger them well in advance

Source: Ogden (1996); Malaterre (1986); Theeuwes (2002); Fuller & Santos (2002); Wickens et al., (2004)

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Expectancy (4)

Expectancies support anticipation and forward planning, and enable drivers and other road users to respond to common situations in predictable and successful ways.

If road users’ expectancies are violated, through poor design of the road and traffic environment, problems are likely to occur because of either:

a) a result of a wrong decision or b) of an overly long reaction time.

Source: Ogden (1996), p. 2.1.16

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Expectancy: Continuation Expectancy

There are three types of driver expectancy:

1. Continuation expectancy • “This is the expectation that the events of the immediate

past will continue...” • e.g. A driver who expects that the preceding vehicle will not suddenly

change speed, so adopts small headways

Source: Naatanen & Summala (1976); cited in Ogden (1996) p. 2.1.16

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Expectancy: Event Expectancy

2. Event expectancy • “This is the expectation that events which have not

happened will not happen.”

• E.g. when a driver stops looking out for trains at railway level crossings, and perhaps for cars at minor intersections as well, because they don’t expect to see trains or cars there where none has been seen before.

• Discussion: How could you design a railway level crossing to mitigate the effects of this type of expectancy?

Source: Ogden (1996), p. 2.1.16

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Expectancy: Event Expectancy (2)

One Possibility The traffic engineer could provide more positive control, such

as an active warning device at railway crossings which requires that the driver respond to the device, not to the presence of a hazard.

Source: Ogden (1996), p. 2.1.16

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Expectancy: Temporal Expectancy

3. Temporal expectancy • This is the expectation that “where events are cyclic (e.g. traffic signals),

the longer a given state occurs, the greater the likelihood that change will occur.

• This is of course a perfectly reasonable expectation, but it can result in inconsistent responses.”

• E.g. A driver who accelerates towards a green traffic signal, that has been green for a long time, thinking that it is increasingly likely that it will change to amber, in contrast to other drivers that start to decelerate.

• Discussion: What can a traffic engineer do to try and avoid this problem?

Source: Ogden (1996), p. 2.1.16

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Expectancy: Temporal Expectancy (2)

One Possibility Ensure, as far as possible, that there is consistency

throughout the road traffic system - for example with the amber and all-red periods at traffic signals, to encourage predictable and consistent driver behaviour.

Source: Ogden (1996), p. 2.1.16

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Expectancy: Design Guidelines

Road and traffic engineers should attempt to ensure that: • “drivers’ expectations are recognised, and unexpected,

unusual or non-standard design or operational situations avoided or minimised – e.g. avoid situations where a ‘Keep Right’ sign is required

if traffic drives on the left, and vice versa, because this is unusual and calls for unfamiliar behaviour)”

Source: Ogden (1996), p. 2.1.17

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Expectancy: Design Guidelines (2)

Road and traffic engineers should attempt to ensure that: • “predictable behaviour is encouraged through familiarity and

habit – e.g. there should be a limited range of intersection design

formats, each appropriate to a given situation, and similar designs should be used in similar situations)”

Source: Ogden (1996), p. 2.1.17

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Expectancy: Design Guidelines (3)

Road and traffic engineers should attempt to ensure that: – “consistency of design and driver behaviour is maintained

from element to element • e.g. avoid significant changes in design speed along a

road

– the information which is provided should decrease the driver’s uncertainty, not increase it.”

Source: Ogden (1996), p. 2.1.17

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Expectancy: Key Take Away

Road and traffic engineers should understand that:

• “…driver behaviour is largely governed by habit, experience, and expectation, and that any design or operation which violates these considerations is likely to be unsatisfactory, and possibly unsafe.”

Source: Lumenfeld and Alexander (1984), cited in Ogden (1996), p. 2.1.6

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Questions ?

Over to ….

Prof. Michael Regan, PhD Research Centre for Integrated Transport Innovation

(rCITI) Room 112, Civil Engineering Building (H20)

E: [email protected]

CVEN4405: Human Factors in Civil and Transport Engineering

Human Performance Limitations and Traffic Engineering 3:

Memory and Decision Making Term 3, 2020

Week 5, Lecture 1b

55

Lecture Recordings

PLEASE NOTE.

All lectures today are being recorded.

Participation in this meeting indicates your consent to be included in the meeting recording.

56

Welcome Back!

57

Course Coodinator and Lecturer

Prof. Michael Regan, PhD Professor of Human Factors

Research Centre for Integrated Transport Innovation (rCITI) School of Civil and Environmental Engineering

University of NSW Sydney

T: +61 (0)2 9385 9504 E: [email protected]

Staff Webpage

58

The CVEN 4405 Teaching Team

Coordinator and Lecturer Prof. Michael Regan Professor of Human Factors Research Centre for Integrated Transport, UNSW Sydney E: [email protected]

Teaching Fellow Dr Prasannah Prabhakharan Research Fellow Research Centre for Integrated Transport, UNSW Sydney E: [email protected]

Demonstrator Mitch Cunningham E: [email protected]

59

Review of Last Lecture

• Perception and Traffic Engineering • Expectancy and Traffic Engineering

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This lecture - Overview

• Three types of memory – revisited • Decision making: general design considerations – revisited • Driving and working memory • Road and traffic design guidelines for working memory • Limited Processing Capacity and Driving • Limited Processing Capacity and Driving: Design

Guidelines • The hysteresis effect

61

Learning Outcomes

CLO1: Explain the fundamental principles of HF that can be used by civil and transport engineers to facilitate user- centred design

CLO2: Apply HF principles, methods and data to the design of road and traffic management systems

CLO3: Plan for the integration of HF into the design lifecycle of the road and traffic management system

Three Types of Memory - Revisited

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Three Types of Memory (1)

We distinguished earlier in this course between three types of human memory:

• Sensory (or iconic) memory • Working memory • Long term memory

Source: Wickens (1992, p. 17). Wickens, C.D. (1992). Engineering Psychology and Human Performance. Harper Collins.

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Three Types of Memory (2)

• Sensory memory - is a temporary storage mechanism that allows people to retain representations of sensory information for very short periods after the original stimulus has ceased

• Working memory - is a temporary storage mechanism that allows you to keep information in your mind for a short period of time (10- 15 seconds) so that it is available for further processing.

• Long term memory – is a more permanent storage mechanism for storing information for the long term and retrieving it later.

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Three types of Memory (3)

• There is a continuous transfer of information between long-term memory and working memory - both retrieval of information and transfer of information.

• Information is retrieved from long-term memory into working memory in order to make sense out of new information that arrives in working memory.

• http://theelearningcoach.com/learning/20-facts-about- working-memory/

Decision Making - Design Considerations Revisited

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Decision making – General Design Considerations

We also talked earlier in the course about decision making, and discussed some of general considerations to take into account when designing things for human use (next slides)

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Decision making – General Design Considerations Revisited (1) 1. “People give an undue amount of weight to early evidence or

information. Subsequent information is considered less important.

2. Humans are generally conservative and do not extract as much information from sources as they optimally should

3. The subjective odds in favour of one alternative or the other are not assessed to be extreme or given as much confidence as optimally they should

4. As more information is gathered, people became more confident in their decisions, but not necessarily more accurate. E.g. people who engaged in troubleshooting a mechanical malfunction are often unjustly confident that they entertained all possible diagnostic hypotheses

Source: Sanders & McCormick, p. 63

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Decision making – General Design Considerations Revisited (2) 5. Human have a tendency to seek far more information than they can absorb adequately

6. People often treat all information as if it were equally reliable, even though it is not.

7. Humans appear to have a limited ability to entertain a maximum of more than a few (three or four) hypotheses at a time.

8. People tend to focus on just a few critical attributes at a time and consider only about two or four possible choices that are ranked highest on those critical attributes

Source: Sanders & McCormick, p. 63

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Decision making – General Design Considerations Revisited (3) 9. People tend to seek information that confirms the chosen course of action and to avoid information or tests whose outcome would disconfirm the choice.

10. A potential loss is viewed as having greater consequence and therefore exerts a greater influence over decision making behaviour than does a gain of the same amount.

11. People believe that mildly positive outcomes are more likely than mildly negative outcomes , but that highly positive outcomes are less likely than mildly positive outcomes.

12. People tend to believe that highly negative outcomes are less likely than mildly negative outcomes.”

Source: Sanders & McCormick, p. 63

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The Focus of This Lecture

In this lecture we will focus on:

• Working memory and driving, and the implications for road and traffic engineering and design

• The limited information processing capacity of the driver, and the implication of this for road and traffic engineering and design, especially to optimise driver decision making

Driving and Working Memory

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Driving and Working Memory (1) • Most of the items of information received by a driver

from the road environment do not pass beyond sensory memory, because they do not require any processing.

• How many road environment inputs can you remember about your drive to work this morning?

• Most of the signs, signals, pavement markings, other vehicles, pedestrians and other items of information which a driver comes across, however, require working memory (Ogden, 1996, p. 2.2.9).

Source: Ogden, 1996, p. 2.1.9

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Driving and Working Memory (2)

• Working memory, as we discussed, is temporary storage mechanism that allows you to keep information in your mind for a short period of time (10-15 secs) so that it is available for further processing.

• In order to keep information in working memory, we have to rehearse it: to actively pay attention to it, code it and rehearse it – otherwise it is lost.

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Driving and Working Memory (3) • Much of the driving task is performed by processing traffic

information which is never processed beyond working memory.

• After use is made of the information (if at all), it fades from working memory without ever entering long-term memory.

• That’s one of the reasons why we tend to remember very little about what we experience during trips.

• What other reasons can you think of as to why we remember very little about our driving trips?

Source: Ogden, 1996, p. 2.1.9

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Driving and Working Memory (4)

• Information in working memory can fade (or be lost) if another item of information enters it.

• If a driver is trying to recall something in working memory, their perceptual ability may also be reduced, and a new signal from the road environment (e.g. a pedestrian stepping out from behind a parked car) may be missed.

Source: Ogden, 1996, p. 2.1.9

Road and Traffic Design Guidelines for Working Memory

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Road and Traffic Design Guidelines for Working Memory (1)

Ogden (1996, p. 2.1.9) presents 3 guidelines for traffic engineering design that take into account the limitations of working memory. These were mentioned during the Week 1 lecture on working memory:

1. Warnings should require an immediate response (i.e. before the warning information fades from working memory, or is replaced by a new item of information)

2. Drivers should be frequently reminded of control information which varies along the road (e.g. speed limits) (i.e. because speed information fades from working memory, or might be replaced by a new item of information)

Source: Ogden (1996), p. 2.1.9

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Road and Traffic Design Guidelines for Working Memory (2)

3. The rate of information gathering which is required by the driver should be limited to ensure that the driver has time to respond to one stimulus before the next one is imposed. (i.e. because the more items of information you have in working memory, the more rapidly it fades)

Source: Ogden (1996, p. 2.1.9)

We also talked about some other, more general, guidelines for engineering design that taken into account the limitations of working memory, that are also applicable in traffic engineering design (next slide ….)

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General Design Guidelines for Working Memory (1)

1. Avoid presenting more than 5 to 9 chunks of information for people to remember (i.e. the magical 7+/-2 rule)

2. Present information in meaningful and distinct “chunks” 3. Provide training on how to better recall information by

chunking

Source: Sanders & McCormick (1987)

Limited Processing Capacity & Driving

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Limited Processing Capacity and Driving

We learned in earlier lectures that we are limited in: • the rate at which we can process and respond to sources of

information • the amount of attention that we have available to perform

activities and tasks.

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Limited Processing Capacity and Driving (2)

So long as drivers are not required to process information from the road environment too rapidly, they can remain in control of their vehicle and work with others to maintain equilibrium within the road traffic system.

However, humans have a fundamentally “single channel” (or one-track) mind – as opposed to a “parallel channel” mind – when it comes to dividing attention between driving tasks that require conscious attention.

Source: Ogden (1996), p. 2.1.3

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Limited Processing Capacity and Driving (3)

Fuller (2002) has proposed a simple model of the interface between driving task demand and driver capability:

Fuller concludes that: • If capability exceeds task demand, the driver is able to

progress safely.

• If task demand exceeds capability, then a collision or loss of control will occur – unless another road user makes some sort of compensatory manoeuvre to help them avoid the collision.

Source: Fuller (2002), p. 5

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The Demand–Capability Interface Model

Source: Adapted from Fuller (2002), p. 6

TASK DEMAND (D)

LOSS OF CONTROL

CONTROL

Safety

CRASH

CAPACITY (C)

C > D

C < D

Compensatory action by

others

Limited Processing Capacity and Driving: Design Guidelines

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Limited Processing Capacity and Driving: Design Guidelines The traffic engineer can design the road environment in a

number of ways to avoid task demand exceeding driver capability:

1. “provide trend information where possible • e.g. the series of signs on an approach to a freeway exit ramp, which

progressively provide advance warning, designation of the ramp, and directional instructions at the terminus of the ramp”

Source: Ogden (1996), p. 2.1.5

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Limited Processing Capacity and Driving: Design Guidelines (2) 2. “avoid the sudden imposition of demand, or the

introduction of extraneous demand when loads on the driver are already high

• e.g. speed limit signs should be a distance upstream or downstream of an intersection, not at the intersection itself”

3. “limit the amount of information presented • e.g. avoid putting too much detail on a direction sign

Source: Ogden (1996), p. 2.1.5

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Limited Processing Capacity and Driving: Design Guidelines (3)

4. require a series of simple decisions rather than a single complex decision

– e.g. use fully controlled turns at traffic signals, rather than requiring drivers to select gaps in oncoming traffic

5. control the rate at which drivers are required to make decisions.”

Source: Ogden (1996), p. 2.1.5

The Hysteresis Effect

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The Hysteresis Effect

There is a hysteresis effect as demand is taken off an overloaded driver.

That is, the driver’s output (performance) is less than it was for the same level of demand as the task demand was increasing.

Cumming and Croft (1973) point out some implications of the human hysteresis for road and traffic design:

Source: Cumming and Croft, (1973); cited in Ogden (1996), p. 2.1.9

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The Hysteresis Effect: Design Implications

1. The ability of drivers to process information may be lower on the departure side of an intersection than the approach side

• might explain whey there are higher pedestrian crash rates on the downstream side of intersections

2. “The use of ‘before and after’ methods of assessing traffic design features may be affected since an accident due to poor performance following overload will not necessarily occur at the feature giving rise to the overload”

Source: Ogden (1996), p. 2.1.10

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The Hysteresis Effect: Design Implications (2)

3. “Pedestrian crossings, bus stops, etc, should not be placed immediately downstream of an uncontrolled intersection.”

Source: Ogden (1996), p. 2.1.10

94

Questions ?

Over to ….

Prof. Michael Regan, PhD Research Centre for Integrated Transport Innovation

(rCITI) Room 112, Civil Engineering Building (H20)

E: [email protected]

CVEN4405: Human Factors in Civil and Transport Engineering

Human Performance Limitations and Traffic Engineering 4:

Self Explaining Roads and Reaction Time

Term 3, 2020

Week 5, Lecture 2

97

CVEN 4405 Human Factors in Civil and Transport Engineering

Term 3 2020 Week 5 - Lecture 2

PRESS RECORD BUTTON

+

SHARE SCREEN

+

PRESS AUDIO BUTTON

98

Lecture Recordings

PLEASE NOTE.

All lectures today are being recorded.

Participation in this meeting indicates your consent to be included in the meeting recording.

99

Welcome Back!

100

Your Course Coordinator and Lecturer

Prof. Michael Regan, PhD Professor of Human Factors

Research Centre for Integrated Transport Innovation (rCITI) School of Civil and Environmental Engineering

University of NSW Sydney

T: +61 (0)2 9385 9504 E: [email protected]

Staff Webpage

101

The CVEN 4405 Teaching Team

Coordinator and Lecturer Prof. Michael Regan Professor of Human Factors Research Centre for Integrated Transport, UNSW Sydney E: [email protected]

Teaching Fellow Dr Prasannah Prabhakharan Research Fellow Research Centre for Integrated Transport, UNSW Sydney E: [email protected]

Demonstrator Mitch Cunningham E: [email protected]

102

Review of Last Lecture

• Three types of memory – revisited • Decision making: general design considerations – revisited • Driving and working memory • Road and traffic design guidelines for working memory • Limited Processing Capacity, Decision Making and Driving • Road and traffic design guidelines for Limited processing • Capacity, Decision Making and Driving • The hysteresis effect

103

This lecture - Overview

• Self explaining roads • Reaction time and driving • Road and traffic engineering design guidance for reaction time

104

Learning Outcomes

CLO1: Explain the fundamental principles of HF that can be used by civil and transport engineers to facilitate user- centred design

CLO2: Apply HF principles, methods and data to the design of road and traffic management systems

CLO3: Plan for the integration of HF into the design lifecycle of the road and traffic management system

Self Explaining Roads

106

Theory – Self Explaining Roads • The driver’s ability to “read the road” is an important

consideration in traffic engineering

• Related to driver expectancies, which we talked about in Lecture 1a this week, is the concept of a “self-explaining road”.

• In last weeks’ Tutorialyou were introduced you to the concept of the self-explaining road.

• In this lecture, we’ll talk a bit more about the theory and concepts behind self-explaining roads.

Source: Dewar, Chapter 12; in Dewar & Olsen (2002)

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Theory – Self Explaining Roads

• “A self-explaining road is a traffic environment which elicits safe and consistent behaviour among road users simply by its design” (Theeuwes & Godthelp, 1992; cited in Cunningham et al. 2017 )

• Self-explaining roads: • communicate to the driver what types of roads they

are • can be easily categorised by drivers as requiring

specific kinds of driving behaviour (Dewar, 2002)

Source: Cunningham, Regan & Cairney, 2017, p.42

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Theory – Self Explaining Roads There are two main mechanisms by which self-explaining roads promote safer driving (Charlton et al., 2010):

• Perceptual properties, such as delineated lane width and roadside objects serve as built-in instructions and guide driver behaviour, either implicitly or explicitly eg perceptual cues that imply a particular speed or lane position.

• Self-explaining roads align with driver expectancies. The use of certain road designs evoke particular (and correct) expectations and driving behaviours from road users, which have been informed by past experience.

• Cited in Cunningham, Regan & Cairney, 2017, p.42

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Theory – Self Explaining Roads

Self-explaining roads need to have a well-defined and easily distinguishable road hierarchy (i.e., different groups of road types) (Theeuwes, & Diks, 1995; Theeuwes, 1998).

These different groups of road types can be categorised based on various design elements that comprise them

e.g. roadway width, curvature, lighting, surface material, planting, and roadside furniture.

Cited in Cunningham, Regan & Cairney, 2017, p.42

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Theory – Self Explaining Roads

Fundamental to self-explaining roads is that these elements, together, are effective in communicating to road users:

• which type of road they are on • what type of traffic (motorised and non-motorised) they

can expect to see • what driving behaviour and speed choice is appropriate.

Cited in Cunningham, Regan & Cairney, 2017, p.42

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Examples of Self Explaining Roads

Paul Hillier from ARRB will talk more about self explaining roads at the tutorial this Thursday, and will show you plenty of pictures.

In the meantime, let’s think about the following: • a Highway (e.g. the Hume) • an Arterial Road (e.g. ANZAC Parade) • a Residential Road (e.g. one of the back streets around the University:

• which road features define each type of road?

• what type of traffic (motorised and non-motorised) can you expect to see?

• what driving behaviour and speed choice does the road make you feel is appropriate?

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Design guidance – Self Explaining Roads Self-explaining roads should fulfil a number of principles (van Vliet & Schermers, 2000; Matena et al., 2006; SWOV, 2007):

• each road category should consist of unique elements (homogeneous within one category and different from all other categories);

• each road category should require a unique behaviour for a specific category (homogeneous within one category and different from all other categories);

• unique behaviour displayed on roads should be linked to unique road elements;

Cited in Cunningham, Regan & Cairney, 2017, p.43

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Design guidance – Self Explaining Roads

• the layout of crossings, road sections, and curves should be linked uniquely with the particular road category

• one should choose road categories that are behaviourally relevant

• the same road category should connect the road section, which is psychologically interpreted as a whole

• there should be no abrupt transitions going from one road category to the next

Cited in Cunningham, Regan & Cairney, 2017, p.43

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Design guidance – Self Explaining Roads

• when there is a transition in road category, the change should be marked clearly (e.g., with rumble strips)

• when teaching the different road categories to traffic engineers, one should not only teach the name of that type of road, but also the behaviour required when driving along it

• category-defining properties should be visible at night as well as in the day-time

Cited in Cunningham, Regan & Cairney, 2017, p.43

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Design guidance – Self Explaining Roads

• the road design should reduce speed differences and differences in direction of movement

• road elements, marking, and signing should fulfil the standard visibility criteria

• the traffic management systems should be clearly connected with special road categories

Cited in Cunningham, Regan & Cairney, 2017, p.43

Reaction Time and Driving

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Reaction Time (1)

• Information takes time to process. • In driving, the term reaction time is used to describe “ the

period between the occurrence or appearance of a ‘signal’ (usually a visual stimulus) and the driver’s physical reaction to it.”

• In Wickens’ (1984) model, it is the period between the appearance of a stimulus and the execution of a response.

Source: Ogden, 1996, p. 2.1.7

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Reaction Time (2)

• Expectancies, as discussed earlier in the course, shorten reaction times because drivers are able to respond through habit and familiarity.

• Drivers have different reaction times because RT is affected by individual characteristics such as experience, skill, degree of alertness, blood alcohol level, etc. We discussed these in earlier lectures.

Source: Ogden, 1996, p. 2.1.7)

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Reaction Time (3)

• Reaction times are not under the control of the road and traffic engineer.

• However, as pointed out by David Milling (from ARRB) during the tutorial last week, road and traffic engineers need to be aware that these variations exist, and design the road and traffic system for as wide a range of driver abilities as possible.

Source: Ogden, 1996, p. 2.1.7)

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Reaction Time (4)

• Studies of driver reaction to show that, for many traffic situations, an average reaction time of around 2.5s is typical.

• However, the variance of the distribution of reaction times is high (McCormick and Sanders, 1982; Garber & Hoel, 1988, p 45; cited in Ogden, 1996, p 2.1.8).

Source: Ogden, 1996, p 2.1.8

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Reaction Time (5)

• Ogden (1996) suggests that traffic design and operations should aim to:

• reduce average reaction times, and • reduce (perhaps more importantly) the variance of

reaction times - especially long reaction times.

Source: Ogden, 1996, p 2.1.8

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Design Guidance for Reaction Time (1)

Ogden (1996) provides the following road and traffic design guidance for accommodating driver reaction times:

1. Encourage familiarity. • this recommendations relates to expectancies; drivers will

react much more quickly to familiar stimuli in the traffic environment

• unfamiliar situations (e.g. unusual intersection layouts or other traffic management treatments) - or unexpected responses - should be avoided.

Source: Ogden, 1996, p 2.1.8

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Design Guidance for Reaction Time (2)

2. Minimise the number of alternatives: • Reaction time increases with the number of alternative

courses of action that are available (i.e. choice reaction time)

• Therefore, the number of alternatives should be limited. • Preferably there should be only two options:

• to maintain the status quo • or to be presented with a single alternative to it.

Source: Ogden, 1996, p 2.1.8

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Design Guidance for Reaction Time (3)

3. Use symbolic signs: • Some signs, including warning, direction and regulatory

signs, may have either a symbol or a written legend, or both.

• There is some evidence showing that RT for symbolic signs is:

• less than that for written legends (Ells and Dewar, 1979; cited in Ogden, 1996)

• more readily understood across language barriers (Donald, 1995; cited in Ogden, 1996).

Source: Ogden, 1996, p 2.1.8

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Questions ?

Over to ….

Prof. Michael Regan, PhD Research Centre for Integrated Transport Innovation

(rCITI) Room 112, Civil Engineering Building (H20)

E: [email protected]