## 5 Conclusions  
Drivers, being the primary users of urban highways and roads, are the most affected by an inappropriate design of urban street-lighting systems. The performance of urban street-lighting systems can be effectively appraised through drivers' opinions gathered with the help of a questionnaire survey. A performance evaluation framework consisting of nine sub-criteria encompassed under three main criteria was designed. Each sub-criterion was appraised through a question posed to the respondents. Chi-squared and Cramer's V tests found a significant association between the evaluation sub-criteria and the performance of USLS. Fuzzy synthetic evaluation aggregated the statistically diverse responses obtained on the lighting design, visibility, and driver satisfaction, the three primary criteria. The primary criteria evaluation revealed that the positioning of electronic billboards, the impact of oncoming vehicle lights, and poor lighting during bad weather (mainly dust) are the main underperforming sub-criteria (factors) affecting the performance of urban street-lighting systems in the study area. Largely, all the primary criteria need further improvement, with performance levels ranging between \"medium\" and \"high\", with no criteria or sub-criteria achieving a \"very high\" performance level.  
The following factors can be included in future studies on the performance assessment of urban street-lighting systems. The impact of lighting on nighttime accidents can be assessed with more accuracy by asking the drivers questions related to the visibility and design of street-lighting, immediately after the occurrence of a crash. Likewise, the information about nighttime crashes that involved a pedestrian can be used to evaluate the height of the luminary design. As vehicle sizes (lightweight or heavyweight) are equipped with headlights of different intensities (lumens), future research should include this factor in the evaluation process.  
The proposed methodology can be used for translating human judgment into a more comprehensible measure for performance improvement of the urban street-lighting system in Qassim (KSA) and elsewhere. The transportation ministries in different regions can add additional measures (factors) to the questionnaire survey to appraise the street-lighting system's performance and driver satisfaction before making improvement decisions, such as conversion to LED lights and smart lighting control systems.  
Conceptualization, A.H.I., H.H. and A.E.M.E.; methodology, A.H.I., H.H. and F.A.; software, F.A.; validation, M.I.A. and A.E.M.E.; formal analysis, H.H. and F.A.; investigation, A.H.I.; resources, A.H.I., F.A. and M.I.A.; data curation, A.H.I. and M.I.A.; writing--original draft preparation, H.H.; writing--review and editing, F.A., A.E.M.E., M.I.A. and I.A.; visualization, F.A.; supervision, A.H.I. and M.I.A.; project administration, A.H.I.; funding acquisition, A.H.I. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Deanship of Scientific Research, Qassim University, with grant No. QEC-2019-2-2-1-5584.  
**Institutional Review Board Statement:** The study was conducted following the ethics rules of Qassim University for conducting questionnaire surveys and was approved on 24 March 2021.  
**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.  
**Data Availability Statement:** All the shareable data have been included in the manuscript.  
**Acknowledgments:** The authors gratefully acknowledge Qassim University, represented by the Deanship of Scientific Research, for the financial support for this research under the grant No. Qec-2019-2-2-1-5584, during the academic year 1440 AH/2019 AD. The authors also extend their gratitude to all the participants who shared their opinions.  
**Conflicts of Interest:** The authors declare no conflict of interest.