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Publication Number: FHWA-HRT-04-139
Date: December 2005

Enhanced Night Visibility Series, Volume VIII: Phase II—Study 6: Detection of Pavement Markings During Nighttime Driving in Clear Weather

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CHAPTER 3—RESULTS

To measure the effect of pavement marking material and VES on pavement marking detection, data on two measures were collected. The first measure was the beginning detection distance, defined as the point where participants indicated first seeing the pavement markings in each section. The second measure was the ending detection distance, when the participants indicated seeing the end of the pavement marking in each section. A series of ANOVAs were conducted to look at the main effects and interactions of pavement marking material, VES, and age for both the beginning and the ending detection distances.

Table 5 represents the results of the ANOVA of the beginning detection distance for VES and pavement marking material. The main effects of VES and pavement marking as well as their interactions were significant (p < 0.05). The post hoc results for the significant main effects and interactions were graphed (figure 11 through figure 14). Means with the same letter (i.e., SNK grouping) are not significantly different.

Table 5. ANOVA table for the beginning detection distance for VES configuration and pavement marking.
Source DF SS MS F value P value
TOTAL 981 4915550.3 5005.7    
Between
Age 2 411512.9 205756.5 3.31 0.0518  
Subject/Age 27 1678307.5 62159.5    
 
Within
VES 10 470638.2 47063.8 25.03 <.0001 *
Age by VES 20 41143.3 2057.2 1.09 0.3551  
VES by Subject/Age 270 507631.0 1880.1    
 
Pvt. Mrkg. 2 442806.9 221403.5 28.73 <.0001 *
Age by Pvt. Mrkg. 4 3462.5 865.6 0.11 0.9777  
Pvt. Mrkg. by Subject/Age 54 416132.0 7706.1    
 
VES by Pvt. Mrkg. 20 17849.5 8912.5 6.62 <.0001 *
Age by VES by Pvt. Mrkg. 40 55268.2 1381.7 1.03 0.4292  
VES by Pvt. Mrkg. by Subject/Age 532 717617.5 1346.4    

Figure 11 shows the SNK results on beginning detection distance for each VES. The HLB configurations (i.e., HLB, hybrid UV–A + HLB, three UV–A + HLB, and five UV–A + HLB) and HOH provided the longest beginning detection distances, and they were significantly different from the HID configurations, the HHB, and HLB–LP. Appendix I shows these results side-by-side with results for the ending distances by VES.

Bar graph. SNK post hoc results on beginning detection distance for the main effect: VES. Click here for more detail.
Figure 11. Bar graph. SNK post hoc results on beginning detection distance
for the main effect: VES.

Figure 12 shows the SNK results on beginning detection distance for each pavement marking material. The fluorescent paint was statistically different from the fluorescent thermoplastic and the liquid system, and it provided the lowest beginning detection distance of the three.

Bar graph. SNK post hoc results on beginning detection distance for the main effect: pavement marking. Click here for more detail.
Figure 12. Bar graph. SNK post hoc results on beginning detection distance
for the main effect: pavement marking.

Figure 13 shows the interaction between pavement marking and VES for beginning detection distance. The fluorescent paint, the thermoplastic, and the liquid system appeared to perform comparably in conjunction with HLB, HLB with UV–A, and HOH. The beginning detection distance for the fluorescent paint diminished compared to the thermoplastic and liquid system when viewed with HHB, HLB–LP, and the HID configurations.

Bar graph. Results on beginning detection distance for the interaction: VES by Pavement Marking. Click here for more detail.
Figure 13. Bar graph. Results on beginning detection distance for the interaction:
VES by Pavement Marking.

A marginal effect was found for age and beginning detection distance. A post hoc SNK (figure 14) indicates that the young age group attained the highest detection distance, which was significantly different from both the middle and older age groups.

Bar graph. SNK post hoc results for beginning detection distance for the main effect: age. Click here for more detail.
Figure 14. Bar graph. SNK post hoc results for beginning detection distance
for the main effect: age.

Table 6 outlines the results for the ending detection distance. The main effects of VES configuration, pavement marking, and age were significant (p < 0.05). The interaction between VES and pavement marking was also significant (p < 0.05). Figure 15 through figure 18 illustrate the post hoc results for the significant main effects and interactions.

Table 6. ANOVA table for the ending detection distance for VES configuration and pavement marking.
Source DF SS MS F value P value  
TOTAL 981 8092123.1      
Between
Age
2 912646.0 456323.0 3.75 0.0367 *
Subject/Age
27 3213675.7 119025.0    
 
Within
VES
10 529420.3 52942.0 13.70 <.0001 *
Age by VES
20 133691.3 6684.6 3.13 0.6665  
VES by Subject/Age
270 1052452.9 3898.0    
 
Pvt. Mrkg.
2 138943.0 69471.5 5.12 0.0092 *
Age by Pvt. Mrkg.
4 31107.1 7776.8 0.57 0.6831  
Pvt. Mrkg. by Subject/Age
54 732624.6 13567.1    
 
VES by Pvt. Mrkg.
20 121992.7 6099.6 3.08 <.0001 *
Age by VES by Pvt. Mrkg.
40 63765.6 1594.1 0.75 0.8735  
VES by Pvt. Mrkg. by Subject/Age
532 1140971.0 2136.7    

Figure 15 shows the SNK results on ending detection distance for each VES. For this evaluation, the HLB configurations and HOH provided the highest ending detection distances, and the results were significantly different from those of the HID configurations, HHB, and HLB–LP. Appendix I shows these results side-by-side with results for the beginning distances by VES.

Bar graph. SNK post hoc results on ending detection distance for the main effect: VES. Click here for more detail.
Figure 15. Bar graph. SNK post hoc results on ending detection distance for the main effect: VES.

Figure 16 shows the SNK results on ending detection distance for each pavement marking material. For this evaluation, the liquid system and fluorescent thermoplastic were the most visible, but the fluorescent thermoplastic was not significantly different from the fluorescent paint.

Bar graph. SNK post hoc results on ending detection distance for the main effect: pavement marking. Click here for more detail.
Figure 16. Bar graph. SNK post hoc results on ending detection distance for the main effect:
pavement marking.

Figure 17 represents the interaction between pavement marking and VES for ending detection distance. Ending detection distances were higher for HLB configurations and HOH in conjunction with all three pavement marking materials. Both the thermoplastic and liquid system had high detection distances with HHB, but the fluorescent paint did not perform as well.

Bar graph. Results on ending detection distance for the VES by Pavement Marking interaction. Click here for more detail.
Figure 17. Bar graph. Results on ending detection distance for the VES by Pavement Marking interaction.

Figure 18 represents the SNK results on ending detection distance for age. Young drivers had significantly longer detection distances compared to the other two age groups.

Bar graph. SNK post hoc results on ending detection distance for the main effect of age. Click here for more detail.
Figure 18. Bar graph. SNK post hoc results on ending detection distance for the main effect of age.

 

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