## 5 Results and Discussion
### Service Performance of the Trial Section
Despite the different paving materials and structures used for the two directional lanes, the concrete had excellent high-temperature stability, which hindered the occurrence of pavement rutting distress to some extent. As a whole, the SDRDI of the NB lane was higher than that of the CS lane, especially the CS3 lane, which possessed the lowest SDRDI of 92.01 and 92.09. SDPWI is used to assess the overall wearing rate of the pavement by measuring the texture depth at the wheel track zone. In the lane towards Ningbo, NB1 had the highest SDPWI with 98.43 and 94.72, and towards Chuanshan, CS3 had the highest SDPWI with 93.97 and 87.38. The results showed that the wear of the pavement was mainly concentrated in the NB2, NB3, CS1, and CS2 lanes, which meant that the skid resistance of these lanes was declining. It is worth noting that the overall SDPWI of the lane towards Ningbo was slightly higher than that of Chuanshan, probably because the top layer of the lane towards Ningbo used SMA-13 gradation. Its road surface roughness was higher than that of the lane towards Chuanshan using the SMA-10 gradation, which was relatively less adversely affected in the process of undergoing friction and impact of tires. Nevertheless, the whole abrasion resistance of the SBDP was unsatisfactory, which may be related to the quality of the aggregates. Consequently, it is necessary to use aggregates with a hard texture and superior abrasion resistance to prevent the rapid deterioration of pavement skid resistance in the initial service period [43]. The SDPQI of each lane was calculated using Equation (1). The results are shown in Figure 12. It can be seen that the SDPQI of each lane towards Ningbo was above 90, among which the right of NB3 lane was the lowest at 90.88; in contrast, the SDPQI of the lanes towards Chuanshan was significantly lower, except for the CS1 lane, which reached 93.80 and 94.32, and all other lanes were below 90. In particular, the SDPQI on the left of the CS3 lane was only 80.58. In order to visualize the service performance condition of each lane, it was divided according to the SDPQI value, as shown in Figure 13. Where 95 \(\leq\) SDPQI < 100 is Excellent, 90 \(\leq\) SDPQI < 95 is Good, 85 \(\leq\) SDPQI < 90 is Moderate, and 80 \(\leq\) SDPQI < 85 is Qualified. Figure 12: Results of SDPQI. As shown in Figure 13, the SDPQI of all test lanes in the NB direction was above 90, with the SDPQI of the left of the NB3 lane reaching 96.34, and exhibiting excellent service performance. For the lanes towards Chuanshan, the CS1 lane performed favorably. However, the CS2 and CS3 lanes had poor pavement service performance, with the left CS3 lane only qualified and the other lanes performing moderately. It should be noted that the lanes near the centerline of the roadway, NB1 and CS1, are fast lanes with a high percentage of lightweight vehicles. In contrast, heavy vehicles generally travel in the NB2, NB3, CS2, and CS3 lanes. The pavement layer in the Chuanshan direction adopted the same ERS system as the old pavement structure, which was susceptible to defects such as rutting, cracks, and potholes under the action of heavy vehicles. On the contrary, although the annual traffic volume was higher in the NB direction, a novel pavement structure, SMAC + EAC, was used in this trial road. After indoor tests, both HSAC and ESAC used in the pavement have outstanding high-temperature rutting resistance and satisfactory low-temperature toughness, which can be well accommodated with the structural characteristics of steel bridge plates. This reduced the occurrence of rutting and cracking defects in the top layer as well as prevented reflection cracks caused by cracks in the bottom layer. Consequently, the novel pavement structure exhibited significantly improved service performance and lower performance degradation compared to the previous pavement solution. Even the NB2 and NB3 lanes, which have a high proportion of heavy vehicles, still performed well after one year of operation.