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07/12/2010
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Functions, research-questions,
hypothesis defined for the FOT
FOT-Net 4th Stakeholders Meeting, Brussels 2010
Dipl.-Ing. Mohamed Benmimoun
2nd December 2010, Brussels
Institut für Kraftfahrzeuge (IKA)
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Agenda
Research questions
Hypotheses
Cost benefit analysis
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Research questions
Work distribution
Analysis of all user related aspects and impacts on
driver behaviour and performance, workload and user
acceptance, social acceptance and usability of the
selected systems.
Identification and quantification of impacts on traffic and
driving safety, traffic efficiency and environment
(economic/”green” driving).
Conduction of a socio-economic cost-benefit analysis
for the selected systems.
WP6300
WP6400
WP6500
WP6100 Management
WP6200 Interactions with other SPs in euroFOT
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Research questions
User related aspects
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User related
aspects
Change in terms of
User
acceptanceDriver workload
Driver
behaviour
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Research questions
Impact assessment
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SafetyTraffic
efficiencyEnvironment
Reduction of
Fatalities
Injuries
Accidents
Fuel
consumptionCongestion
CO2
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Research questions
Tested functions
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Hypotheses
Definition• Hypotheses are defined for each function
• All research questions have been taken into account
• Feasibility of testing hypotheses have been checked
• Several hypotheses have been redefined and in some
cases excluded, when need data is not available
• Examples:• ACC increases situation awareness
• Driver Alert warning leads to an appropriate driver reaction
• ACC increases driver's focus on secondary tasks
• ACC increase drowsy driving
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Hypotheses
Definition• Hypotheses needs to be prioritized, in order
to limit number of hypotheses
• Altogether 236 hypotheses have been
defined in in the beginning (for 8 functions)
• 81 hypotheses just only for ACC
• Additional hypotheses have been defined,
in order to investigate several aspects
relevant for the impact assessment and
CBA
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1 ACC decreases incidents.
2 ACC decreases the time to reach the brake pedal.
3 ACC increases time to headway.
4 ACC decreases the variaibility of time to headway.
5 ACC improves LDW performance.
6 ACC decreases speed violations.
7 ACC makes safer the approaching phase.
8 ACC reduces occurence of strong decelerations.
9 ACC decreases average speed.
10 ACC increases following distance.
11 ACC leads to a greater minimum distance when initiating an overtaking manouver.
12 ACC decreases severe injuries and fatalities.
13 ACC decreases occurrences of short time to headway (below 1s, below 1.5s?).
14 ACC reduces the occasions of travelling above 120 km/h.
15 ACC favours for the drivers will enter construction sites, curves and exit ramps at higher speeds.
16 ACC increases incidents on entrance ramps.
17 ACC decreases hard braking occasions.
18 ACC decreases the number of critical TTC's.
19 ACC increase the probability of other vehicles cutting-in manouvres
20 ACC makes the driver less prompt to intervene overriding the ACC in urban area
21 ACC speed will be set higher than the speed the driver would actually choose withouth ACC.
22 With FCW with assisted braking, some of the hard braking due to the ACC system is reduced (smoother transition to manual driving).
23 ACC decreases fuel consumption.
24 ACC increases fuel consumption in mountainous terrain.
25 ACC decreases emissions of CO2, NOx, PM.
26 ACC increases traffic flow performance.
27 ACC decreases use of residential roads.
28 ACC favours longer use of the fast lane.
29 ACC increases throughput (with higher penetration rates).
30 ACC prevents congestion through homogenisation of speeds (at higher penetration rates).
31 ACC homogenisation effects are most pronounced on motorways.
32 ACC vehicles influences the speeds of other, following vehicles.
33 ACC decreases the number of lane changes.
34 ACC has no influence on the driver's steering behaviour.
35 ACC increases situation awareness.
36 ACC increases driver's focus on secondary tasks.
37 ACC favors driver's drowsiness.
38 ACC decreases visual monitoring of the speed indicator.
39 ACC is overridden before overtaking by pressing the accelerator (drivers would initiate the lane change earlier) depending on locus of control.
40 ACC is not overrridden while overtaking (consequently low difference in speed between vehicles) depending on locus of control.
41 ACC makes drivers wait longer to adjust their speed to a lower speed limit.
42 ACC presence in the vehicle induces people to drive more km's.
43 ACC presence in the vehicleinduces people to drive more at night.
44 ACC presencein in the vehicle induces elderly drivers to drive more.
45 ACC makes lateral control worse (because drivers are less attentive). However, with LDW, this effect will be mitigated.
46 LDW mitigates the effect of ACC on lateral control.
47 ACC increases driver propensity to perform non-driving related tasks.
48 ACC increases secondary task performance.
49 ACC use changes over time.
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ACC OFF-switch is mainly used to deactivate the system and not to override the system.
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52 ACC use increases over time.
53 ACC "safe distance" setting is mainly used by the driver.
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ACC use depends on driver experience, driver's drowsiness, and weather conditions.55
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In case of un-expected ACC behaviour the driver can take over accordingly to the traffic situation.
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ACC usage depend on traffic situation for experienced drivers.
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ACC use depends on type or road (highway, narrow roads, etc...) and traffic events (convoi traffic, high traffic, etc...).
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63 ACC speed is set by the drivers slightly above the speed limit.
64 ACC minimum headway is always set by the drivers, except when a very high speed setting is chosen and in the case of elderly drivers.
65 ACC is used more often in bad weather than in good weather.
66 ACC is used more often in darkness than during daylight, because car following is harder.
67 ACC selected headway increases in bad weather and in the dark (except when the road is lit).
68 ACC will not be turned off at construction sites, curves and on/off ramps (because the drivers forget).
69 ACC speed settings are used rather than the off-switch to increase or decrease speed.
70 ACC will be overridden earlier the more experienced are the user (the user can better anticipate the need to override the ACC).
71 ACC settings are not adjusted in adverse weather by the drivers.
72 ACC settings are not adjsuted by the drivers in dangerous curves. With CSW, this effect will be mitigated.
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ACC increases driving perceived safety and comfort.
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78 ACC annoys the driver by braking harder than the driver would when cutting in behind a vehicle.
79 ACC annoys the drivers in the following vehicles when the driver has to override the system by braking.
80 ACC acceleration and deceleration dynamics annoy the driver
81 ACC reduces driving pleasure, depending on driver personality.
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Hypotheses
Breakdown process
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Research questions:
e.g. impact of ACC on safety,
environment, traffic efficiency etc.
Hypotheses:
e.g. ACC decreases number of
incidents
Performance indicators
e.g. number of incidents
Signals
e.g. vehicle speed, distance to forward
vehicle, deceleration etc.
Breakdown of
hypotheses
Adaptation of
data analysis
plan
Implementation
of analysis tools
Definition of
needed
subjective data
Questionnaire
content
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Hypotheses
Definition
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Hypothesis Reason Comparison Control factor
Situational variable
Event Performance indicator
ACC reduces
number of hard
braking
ACC brakes
earlier and
softer
For trucks:
baseline,
treatment ACC
on, treatment
ACC+LDW on,
For cars:
baseline,
treatment ACC
on, treatment
ACC off,
baseline 2
trip type: trips
longer than 5
minutes
road type: non-
urban roads
Trailer load,
weather,
passengers,
road type,
speed limits,
system state,
traffic density,
lighting,
curvature, day
of trial
Hard
braking,
Incident,
number of hard
braking
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Hypotheses
User related aspects• User related aspects are mainly tested by means of
questionnaire
• User related aspects cover several functional related
aspectsAcceptance
Abuse and misuse
Change of user practices over time
Trust
Perceived comfort
Perceived safety
Usage
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Hypotheses
Impact assessment• Hypotheses for safety, traffic efficiency and
environment cover the following aspects:Incident events
Hard braking events
Hard acceleration events
Number of trips
Number of kilometres travelled
Percentage of THW/TTC/TLC below x s
Fuel consumption
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Hypotheses
Function related aspects• ACC:
Usage of brake pedal
Override behaviour
Distance behaviour
• LDW:Night driving
Usage of turning indicator
Lane change behaviour
• IW:Driver reaction after driver alert
Frequency of drowsy driving
• CSW:Braking behaviour before entering a curve
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Cost-benefit analysis
Approach
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Quantification of benefits of analysed functions
(WP6400)
Safety (reduction of fatalities, injuries,
accidents etc.)
Efficiency (reduction of congestions)
Environment (red. of fuel cons. and CO2
emissions )
Translation of physical impacts into monetary benefits for society and customer
(direct and indirect costs for reduced accidents, congestions etc. based on existing cost statements)
Determination of installation and consequential costs (e.g. maintenance etc.)
Consideration of additional influencing factors (e.g. expected penetration rates, incentives etc.)
Determination of benefit-cost ratio
• Socio economic cost-benefit analysis: The methodology is based
on the approaches of previous national and European projects,
like eIMPACT etc.
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Thank you for your attention…
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