Problem
A substantial increase in both the number and proportion in total population of older adults is expected for most developed countries. A main point of consideration for road designers and road safety engineers is the resulting rise in the number and proportion of older road users, who, given their physical vulnerability and limitations in terms of perceptual, cognitive, and psychomotor performance, would be more likely to have problems in driving and as pedestrians
(Staplin et al, 2001), and to adapt (self-regulate) their behavior accordingly. User-centered roadway design and road improvements should accommodate older road users, the fastest growing population group, by addressing their information needs, limitations and capabilities— and in addition, their perception of risk.
A critical highway safety issue is the potential discrepancy between the “objective” risk that is attributed to roadways (road sections, road sites) by road safety professionals’ tools and the “subjective” risk attributed by road users. Such discrepancies can reveal how well roadway infrastructure is understood, perceived, and responded to by road users. This knowledge can inform designers’ ability to accommodate (older) road users, and guide development of educational countermeasures with the potential to influence the perceptions of this group in a manner that enhances their mobility.
Objective
The objectives of this research are 1) to determine the correlation between the level of safety of particular roadway sites/sections, as perceived by aging road users, and the level of safety provided to the road user according to the International Assessment Programme (iRap)
Star Rating protocol; and 2) to identify the site characteristics that account for observed discrepancies between the objective ratings and subjective estimations.
The needed research will reveal the correlation between subjective estimated road safety and the RPS, as attributed to the road sections by the Star Rating protocol (see below), and the identification of specific roadway characteristics that most strongly influence perceived safety.
Analyses of discrepancies between objective calculations and subjective estimations (implying either overestimation or underestimation by drivers of the safety level of the various road sections) will reveal the design elements that individually or in combination account for these
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discrepancies. The results of this study could provide valuable input into roadway design and improvements that accommodate older road users, and aid in the development of educational countermeasures for this group.
Key Words
Subjective safety, objective safety, older road user, risk perception, risk awareness
Related Work
Research has demonstrated the effect of different roadway design elements on driver behavior and safety perceptions (Ben-Bassat and Shinar, 2011). Research indicates that older people perceive risk as something external (e.g. bad infrastructure) that can sometimes be managed through internal means. According to Siren and Rishoj Kjaer (2011), they interpret self-regulation and compensation in their driving as a response to external risk factors rather than a reflection of their own actual risk or abilities. These findings raise a concern that older persons may experience risks and threats in the traffic environment in such a way as to lead to a lack of confidence in driving, and overestimation of risks; this in turn could have more severe negative consequences in its impact on mobility than a potentially biased assessment of risk (Siren and
Rishoj Kjaer, 2011).
Horswill et al. (2011) have stated that self-assessment of driving ability may be used by drivers to determine the degree to which they restrict their driving. The problem is that drivers have little insight into their own driving ability (including hazard perception ability). This may impact the potential road safety benefits of self-restriction of driving because drivers may not have the information needed to optimally self-restrict.
Objective safety refers to the use of a quantitative measure, which is independent of the observer. Subjective safety – or how safe a person feels on a specific section of road – for the same site may vary substantially between observers (HSM, 2009).
A road’s Star Rating is based on an inspection of road design elements which are known from extensive research to influence the likelihood of crashes occurring and the severity of those crashes that do occur (AusRAP, 2006). iRAP Star Ratings provide a simple and objective measure of the level of safety which is “built-in” to the road for car occupants, motorcyclists, cyclists and pedestrians (iRAP, 2009). Star ratings have been developed using iRAP protocols.
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iRAP’s approach was to adopt the best concepts from EuroRAP, AusRAP, and usRAP and combine these into RPS (Road Protection Scores) criteria and Star Rating protocols which incorporate both crash likelihood and crash protection considerations. iRAP’s RPS criteria and
Star Rating protocol appear promising for application as a road assessment tool in the United
States (usRAP, 2010). RPS is the sum of RPS for the relevant crash types (run-off RPS, head-on
RPS, intersection RPS), which are in turn a function of likelihood, severity and crash-type calibration factors. A high score equates with a high level of risk and a low score with a low level of risk. Between 1 and 5 stars are awarded to roads depending on the level of safety that is
“built in” to the roadway (iRAP, 2009).
Urgency/Priority
High. Provided with the proper information, designers and road safety professionals can produce safer road design and roadway improvements matched to aging road users and provide input into appropriate educational programs, increasing aging road users’ self-awareness and improving their risk awareness. The research findings could have important implications for safety and mobility of the aging road users.
Cost
$250,000, with a sample of 30 normally aging (no acute medical conditions or functional impairments known to impair driving) drivers including both 65-74 and 75+ cohorts.
User Community
Highway designers, traffic engineers involved in the design and operation of highway facilities, road safety professionals and researchers concerned with issues of older road user safety and mobility; and those who develop educational countermeasures for older drivers and pedestrians.
Implementation
Work on Road Assessment Programs is currently ongoing, with many countries planning to extend them to their road network after the success of their pilot projects. With RAP being in a relatively early phase of implementation, the proposed research on road user participation
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would be readily implementable as inputs to roadway design and improvements, and to education and training programs to improve older drivers’ risk and state awareness. These findings could also have the potential to improve education regarding the use of roadway safety countermeasures, heightening their social acceptability and ultimately their effectiveness.
Moreover, they might provide valuable input and support for decision-making regard the need to implement countermeasures programs.
Effectiveness
The effectiveness of design improvements and of countermeasures implemented based on the results of this research would be indicated by increased use of road sections (with the characteristics studied in this research) by older drivers, at operating speeds that are safe and appropriate to the Star Rating of the roadway.
References
Highway Safety Manual, 1 st
Edition, 2009.
AusRAP (2009). Safer Roads Save Lives. RAC VIC.
( http://www.ausrap.org/ausrap/media-centre/reports/pdfs/2006-10-00-star-ratings-forvictorian-highways.pdf
) iRAP (2009). Star Rating Roads for Safety The iRAP Methodology (http://www.irap.org) usRAP (2010). Pilot Program Phase III. AAA Foundation of Traffic Safety.
( http://www.aaafoundation.org/pdf/usRAPIIIFinalReport.pdf
)
Siren, A., Rishoj Kjaer, M. (2011). How is the older road users’ perception of risk constructed.
Transportation Research Part F, 14, 222-228.
Ben-Bassat, T., Shinar, D., (2011). Effect of shoulder width, guardrail and roadway geometry on driver perception, Accident Analysis and Prevention, 43, 2142-2152.
Horswill M., S., Anstey, K., J., Hatherly, C., Wood J.M., Pachana, N., A. (2011). Accident
Analysis and Prevention 43, 2121-2127.
Staplin, L., Lococo, K., Byington, S., Harkey, D. (2001). Guidelines and recommendations to accommodate older drivers and pedestrians . Report FHWA-RD-01-051, Federal Highway
Administration, U.S. Department of Transportation, McLean VA.
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Submitted by:
Dr. Sophia Vardaki
National Technical University of Athens (NTUA)
Department of Transportation Planning and Engineering
5 Iroon Polytechniou St, 157 73 Zografou, Athens. Greece phone 
+30.210.7721282 fax: 
+30.210.7721327
email: sophiav@central.ntua.gr
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