1. Pilot Results on Forward Collision Warning System
Effectiveness in Older Drivers
Benjamin D. Lester1, Lauren N. Sager2, Jeffrey Dawson2, Sarah D. Hacker3, Nazan Aksan3, Matthew Rizzo4,
& Satoshi Kitazaki5
1Human
Factors
Prac/ce,
Exponent
Failure
Analysis
Associates,
Phoenix,
U.S.A.;
2Department
of
Biosta/s/cs,
3Department
of
Neurology,
University
of
Iowa,
Iowa
City,
Iowa,
U.S.A.;
4Neurological
Sciences,
University
of
Nebraska
Medical
Center,
Omaha,
NE,
U.S.A.;
Na/onal
Ins/tute
of
Advanced
Industrial
Science,
Japan
In each scenario, drivers
followed a lead veh50, 55,
& 60 M.P.H. at random
intervals. Drivers adjusted
their speed to match the
LV’s speed✔
✔
Abstract
Advanced Driver Assistance Systems (ADAS) have largely been
developed with a “one-size-fits-all” approach. This approach
neglects inter-individual variability in perceptual and cognitive
abilities that affect aging drivers. This study investigated the
effectiveness of a forward collision warning (FCW) with fixed
response parameters in young and older drivers. Older drivers
showed significantly slower responses at several time points,
compared to younger drivers. The FCW facilitated response
times (RTs) for older and younger drivers. However, older drivers
still showed smaller safety gains when the FCW was active. No
significant differences in driver risk metrics were observed in the
current scenario. The results demonstrate older drivers likely
differ from young drivers using a fixed-parameter FCW. Future
research should investigate potential relationships between
cognitive functioning and ADAS responses, to develop parameter
sets to better fit the individual driver.
Background & Aims
The number of drivers 65 and older in the U.S. is rapidly increasing, and
will continue to rise in coming decades.
Concrete data on ADAS in older adults is strongly lacking. It is
largely unknown how cognitive status and physical limitations
might interact with ADAS system parameters (Davidse, 2006;
Jamson et al., 2008).
Methods
Results
Conclusions
Older drivers showed reduced cognitive functioning in processing speed,
visuospatial abilities, memory, and executive functioning.
Older drivers showed slowed responses during the pedestrian incursion.
FCW improved responses in the incursion, but age-related slowing persisted
when FCW was active.
FCW and age did not influence scenario risk penetration. This is likely due to
the relatively low criticality of the current pedestrian incursion.
Future investigations will examine how cognitive and physical limitations in
aging might inform ADAS design, in an effort to tailor in-vehicle systems to the
individual driver.
Acknowledgements
This research was supported by a grant awarded from the Toyota Collaborative Safety Research Center (CSRC).
Candidate drives were extracted from a larger simulator dataset. Seven
drives made by neurologically-normal older drivers (M = 77.6 years, SD =
7.5) and 6 drives by younger controls (M = 39.4, SD = 9.1) were entered
into the analyses.
Participants encountered an unexpected pedestrian incursion, with and
without the FCW system (Figure 1).
The FCW system consisted of visual and auditory components. The visual
component appeared in a heads-up design, using a graded alert design.
-- This pilot study examined FCW effectiveness in a driving scenario
isolated from a larger simulator study of ADAS effectiveness.
Figure 1. Quad-cam views of the driver and a image of the pedestrian scenario, during
a FCW-on drive.
From 1999-2009, the number of licensed drivers 65 and older increased
by 23%, with 33 million licensed older drivers on the road in 2009 (FHA,
2009).
Older drivers are at an increased risk for automobile accidents and on-
road fatalities in certain contexts (NHTSA, 2009).
ADAS development began in the automotive industry in the early 90’s, in
an effort to increase safety and facilitate situational awareness.
However, current in-vehicle technologies are developed and tested with
healthy young drivers in mind (Rakotonirainy & Steinhardt, 2009).
-- We examine ADAS effectiveness, risk metrics, and initial
explorations of cognitive functioning in a pilot sample of older and
younger drivers.
Older adults were slower at accelerator pedal release (AP) and brake pedal touch
(BP) during FCW-off drives (ps < .03), compared younger drivers. No significant
differences were observed for maximum brake depression (MBP; p =.62). FCW
facilitated responses at AP release and BP touch (ps < .05) for all drivers.
Importantly, age-related slowing of responses persisted at AP release and BP
touch (ps < .09) when FCW was active.
As the age demographic shifts, a “one-size-fits-all” approach to ADAS
development may be suboptimal for improving vehicle safety.
Predictions
1. Older drivers should have reduced cognitive functioning in several
domains.
2. Older drivers should show slower responses during the
pedestrian incursion.
3. FCW should improve responses in all drivers, but safety gains will
differ for older drivers.
4.Older drivers should show greater risk penetration during the
incursion, even when FCW is active.
Cognitive Domains
Older adults showed reduced cognitive functioning on several
neuropsychological domains, compared to younger adults. Older adults had
significantly lower scores in processing speed (p < .001), visuospatial abilities
(p = .026), overall memory (p = .056), and executive function (p = .030).
Response Times
0
200
400
600
800
1000
1200
1400
1600
1800
AP release BP touch MBP AP release BP touch MBP
Older Younger
RT(inmilliseconds)
FCW off
FCW on
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
Older Younger
Maximumdeceleration(m/s^2)
FCW off
FCW on
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
Older Younger
MinimumTTC(inseconds)
FCW off
FCW on
FCW did not significantly influence maximum deceleration or minimum TTC (ps > .
26). Similarly, age status did not significantly influence either metric (ps > .12).
Risk Metrics
Z150288-9459