Farzaneh Shahini| Portfolio
Analysis of Advanced Driver Assistance Systems in Police Vehicles: A Survey Study
Funding: U.S. department of transportation
My Role: graduate leader and researcher
Timeline: Feb 2021-July 2021
Research Method: Survey, qualitative and quantitative analysis of the survey
Story
Few studies have examined the impact of advanced driver-assistance systems (ADAS) on police officers to improve driver safety and prevent crashes. This is in spite of police officers having higher driving-related mortality rates than average civilians. To fill this gap, a survey study was conducted on 73 police officers to assess their opinions on various ADAS features as well as their recommendations for improvement. Results of the correlation analyses indicated that officer behavior and opinion on ADAS features were influenced by the trust officers had in the available ADAS systems among other key factors such as ADAS training and perceived usefulness. On this basis, guidelines for future research and development of ADAS were provided to improve officer driving safety in police operations. The guidelines need to be further validated in future driving simulation or naturalistic studies
Research objective
The objective of this study is to understand police officers’ opinions and needs regarding ADAS in police vehicles. To achieve this objective, an online survey is conducted to identify correlations and trends between officer opinions on ADAS features in their vehicles. Also, a technology acceptance model (TAM) was conducted to investigate officers' intention and acceptance to use ADAS technologies in future.
Methods
Participants:
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Survey questionnaire:
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Technology Acceptance Model (TAM):
Data analysis:
Correlation analysis was used to understand the relationships between the individual responses. For comparisons between two yes/no questions, the phi correlation coefficient test was used. This test compromises a nonparametric statistic used in cross-tabulated table data where both variables are dichotomous. The assumptions of the phi test, including having samples randomly and independently selected from a defined population with expected values of at least 5, were met. Comparisons between two Likert scale responses were conducted by the Kendall rank correlation. The Kendall rank test was the best alternative to the Spearman’s rank correlation, as the results collected for the survey failed one of the assumptions of the Spearman’s rank correlation in addition to having many tied ranks. Finally, comparisons between yes/no and Likert scale responses employed the Wilcoxon rank sum correlation with the assumptions for the test met. Free response questions were analyzed using conventional quantitative analysis separate from the analysis conducted on the other questions.
To analyze the structural model, we used the PLS-SEM technique using the SmartPLS 3.2.9 software. To ensure that the model used was valid, the indicator reliability, internal consistency reliability, convergent reliability, discriminant validity, and model fit of the model were evaluated. below shows that that all of the indicators have individual indicator reliability values that are much larger than the minimum acceptable level of 0.4.
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Results
Descriptive statistics on Likert scale questions:
Summary of responses to Yes/No questions:
Beneficial ADAS features:
Beneficial ADAS features:
Technology acceptance model (TAM):
officer’s trust in technology (β = 0.26, t = 2.27, p = 0.01, f2 = 0.07) and ADAS training (β = -0.35, t = 3.54, p< 0.01, f2 = 0.14) affected officer’s behavioral intention to use ADAS, explaining 25% of the variance in their behavioral intention. ADAS training (β = 0.4, t = 2.69, p< 0.01, f2 =0.2) was also found to be a significant predictor of driver’s perceived usefulness of ADAS features.
Guidelines:
Guideline 1: Emphasize clarity above everything else.
About 68% of respondents affirmed that they would make greater use of ADAS if the functionality and advantages were more clearly explained. Since ADAS training significantly impacts perceived usefulness and officers’ intention to use these features, improving officers’ knowledge of ADAS can potentially increase ADAS acceptance among police officers.
Guideline 2: Improve ADAS accessibility and usability
About 38% of police officers stated that there were situations where they preferred to have their ADAS features disabled. However, over half of the respondents identified that they were unable to easily turn on or off their ADAS features. Accessibility and usability, desired qualities according to the free response results, should be emphasized in the design of ADAS to account for individual differences and preferences of police officers when using ADAS features.
Guideline 3: Provide adaptive ADAS
Police driving conditions including pursuit and emergency operations are different from the situations that civilian drivers are involved in. Therefore, ADAS features for police vehicles should be easily adaptable to these situations or powered off effectively otherwise.
Guideline 4: Investigate ways to integrate ADAS into existing police vehicle technology.
Officers indicated that ADAS should be compatible with existing police in-vehicle technologies and should be easily activated or adjusted based on individual preferences, needs, and driving situations. This highlights a need for a unique approach to design and manufacture ADAS for police vehicles.
Guideline 5: Focusing on perfecting a few features is better than having many less elaborate features.
The survey indicated the lack of understanding regarding ADAS as one of the primary barriers towards using ADAS features for police officers. To combat this, researchers and manufacturers should focus on ADAS features, which target the factors specified above when designing for police vehicles, with future research validating the directions chosen for designing such features. Furthermore, building the trust that compromises the main significant contributor towards officers’ intention to use ADAS requires that officers understand the nature of the features they are using.
Guideline 6: Police vehicle ADAS features should focus on improving officer driving safety
Roughly a third of respondents rated the extent to which ADAS features reduce their workload as a 1 out of 5 on the Likert scale, as low as possible. However, more than half of the responders believed that ADAS can improve their driving safety. The findings of this survey indicated that police officers might prioritize ADAS features with regards to avoiding collisions such as intersection collision avoidance over other ADAS such as traffic sign detection or autonomous highway driving, which might be due to the unique driving situations that they are involved in. Police vehicle manufactures should prioritize integration of those ADAS features, which have the greatest potential to improve officers’ driving safety.
Guideline 7: Design to reduce the need for extensive ADAS training
The results indicated that ADAS training has a significant effect on officer intention to use ADAS and perceived usefulness of ADAS. Useful as ADAS features are, the prospect of needing to undergo training to fully understand and utilize these features can be daunting to police officers already burdened with high mental workload and stressful jobs.