# Coordinated Multi-Platooning Planning for Resolving Sudden Congestion on Multi-Lane Freeways
## 5 Implementation and Experimental Results
We observed that traffic congestion due to the accident needed around 900 to 1000 s to clear out; therefore, we compared the delay of vehicles driving through the congestion area around this time. Specifically, in Lane 0, Figures 6a-8a show that the average delay of the vehicle \(i\) ranges from 100 to 250 when it uses and does not use the proposed planning scheme. In Lane 1, Figures 6b-8b show that the average delay of the vehicle \(i\) ranges from 90 to 190. In Lane 2 (Figures 6c-8c), vehicle \(i\) is shown to range from 90 to 230. In Lane 3 (Figures 6d-8d), vehicle \(i\) is shown to range from 40 to 120. The last number represents the last vehicle in the lane to pass the accident spot before the accident is cleared. Therefore, we observed that there were 790 vehicles in total from when the first vehicle receives the warning notification until the accident is cleared. Figure 5: The average platoon size in Lane 0 to Lane 3 in three scenarios of simulations. Figure 6: _Cont._  
In the first scenario (Figure 6), the vehicles receive an accident warning 3500 m ahead of the accident spot. With a substantial distance for platoon forming, the proposed system can smoothly schedule the vehicles into platoons to exit the congestion area. By contrast, as shown in Lane 0 (Figure 6a), the delay of the 250 th vehicle in the case without the proposed scheduling scheme (red line) is approximately 14.64 s longer than the case using the proposed scheduling scheme. In other words, the proposed system reduces approximately 22% of the congestion delay on average. In addition, in Lane 1 (Figure 6b), Lane 2 (Figure 6c), and Lane 3 (Figure 6d), the delay reduction in its last vehicle is 11.22 s, 9.89 s, and 5.43 s, respectively. We observed the delay reduction for all vehicles in the exit  
Figure 6: The mean time taken for the vehicles to exit the congestion spot if they receive an accident warning 3500 m ahead of the accident spot. lane and compared them to their respective red lines. The oscillating curve behavior occurs when a vehicle joins the platoon and accelerates to catch up with the preceding vehicle. The downward swing is normal. However, if the platoon-based vehicles oscillate less, it means that the platoons do not interfere with incoming vehicles in the exit lane when making lane changes. As a result, regardless of the platoon size, the platoon-based vehicles can leave the accident spot quickly. Figure 7: Cont. Figure 8: _Cont_. Figure 7: The mean time taken for the vehicles to exit the congestion spot if they receive an accident warning **2500** m ahead of the accident spot. In the second scenario (Figure 7), the vehicles receive the accident warning 2500 m ahead of the accident spot. We reduced the warning distance by 1 km, equal to approximately 33 s to 45 s shorter than the first scenario, in receiving the notification. Nonetheless, the proposed algorithm is still effective for the vehicles to pass the accident spot. As shown in Lane 0 (Figure 7a), the congestion delay of the 250 th vehicle is reduced by approximately 10.73 s by using the proposed CPP algorithm. In addition, in Lane 1 (Figure 7b), Lane 2 (Figure 7c), and Lane 3 (Figure 7d), the delay reductions in the last vehicle are approximately 6.24 s, 5.01 s, and 3.96 s only, respectively. The result means that the distance when receiving the warning notification is still great enough to allow vehicles to form the platoons and follow their platoon leader to maintain a safe inter-vehicle gap and successfully execute smooth lane-changing actions. In the third scenario (Figure 8), the warning distance is reduced to 1500 m. As shown in Lane 0 (Figure 8a), the congestion delay of the 250 th vehicle is reduced by up to 7.4 s if using the proposed CPP algorithm. In addition, in Lane 1 (Figure 8b), Lane 2 (Figure 8c), and Lane 3 (Figure 8d), the delay reductions in the last vehicle are 4.31 s, 3.94 s, and 3.2 s, respectively.