# Physarum-Inspired Bicycle Lane Network Design in a Congested Megacity
## 4 Computational Experiments
### Test Case 1: BLN for Central Dhaka Area
#### 4.3.1 BLN Design Solution for Central Dhaka  
Figure 4 depicts the proposed BLN, in blue, for the central Dhaka area on its road network. The numerical values in the BLN map indicate corresponding link lengths in km. As desired, the BLN is designed such that the main roads are not intercepted much, except in a few cases where an alternative is not available or not suitable. For example, the path from node 17 to node 18 (located on opposite sides of the map) is available through 16-23-24-26-29, i.e., without using the main roads. The proposed BLN uses main roads in a few cases, when an alternative is not possible. For example, there is a direct main road sharing with BLN between neighbour nodes 2 and 6, in two small segments, since an alternative route, such as 2-10-7-6, is very long. Such consideration of small portions of \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Sl** & **Location** & \
\begin{tabular}{c} **Traffic** \\ **Pressure** \\ \end{tabular} & **Sl** & **Location** &
\begin{tabular}{c} **Traffic** \\ **Pressure** \\ \end{tabular} \\ \hline
01 & Motijheel & 9 & 16 & Kotwali & 3 \\
02 & Mohakhali & 8 & 17 & Lalbagh & 4 \\
03 & Gulshan & 5 & 18 & Khilgaon & 6 \\
04 & Shahbinga & 8 & 19 & Taltola & 3 \\
05 & Tejgaon & 9 & 20 & Afrthapagar & 4 \\
06 & Badda & 4 & 21 & Sadarghat & 5 \\
07 & East West Unv. & 5 & 22 & Matauil & 8 \\
08 & Bashundhara & 5 & 23 & Wari & 7 \\
09 & Mogbazar & 5 & 24 & Golapbag & 5 \\
10 & Mirbag & 5 & 25 & Donia & 3 \\
11 & Dhanmomdi & 7 & 26 & Rajarghagh & 5 \\
12 & Shahbag & 9 & 27 & Sobujagh & 5 \\
13 & Unv. of Dhaka & 9 & 28 & Green Model Town & 4 \\
14 & Kamlapur & 8 & 29 & Nandipara & 6 \\
15 & Ramna & 5 & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The location wise traffic pressure assignment for central Dhaka area. Figure 3: Schematic view of the central Dhaka area’s road network, where main and local roads are shown with wider and thinner lines, respectively. main road is sensible to make the network feasible. Another important BLN feature is the several alternative connectivities among nodes, e.g., the optimal route to connect nodes 21 and 28 is 21-24-28, and the alternative routes are 21-23-14-28 and 21-25-22-28. Such feasible alternatives are essential to increase the resilience of the network. Table 2 shows the resulting optimal routes and corresponding distances and travel times from node 1 to other individual nodes, using the proposed BLN shown in Figure 4. Notably, node 1 (Motijheel on the map) is in the centre of the BLN and the most demanding place to visit from different locations, due to its commercial importance. The travel time is calculated considering a standard bicycle speed of 20 km/h [46]. Along with cycling time, 5 min is also added for each main road crossing by bicycle to better reflect reality. According to the proposed BLN, node 3 (Gulshan on the map) is the farthest away from node 1 and route 1-9-10-2-3 (and vice versa) is 9.8 km, which requires 34.4 min including 5 min for travelling across the main road between nodes 2 and 3. The second farthest node is 22, route 1-23-21-25-22 (and vice versa) is 10.3 km and would take 35.9 min. The travel time for any other node is less than 30 min. Node 11 and node 18 are the farthest nodes from node 1 in the left and right directions, respectively, and travel time is less than half an hour using routes 1-12-11 (distance 7.6 km) and 1-29-18 (distance 7.8 km). On the other  
Figure 4: Proposed bicycle lane network (BLN) in the central Dhaka city area, depicted in blue color. Numerical values in BLN links indicate corresponding link’s length in km. hand, travel time between two opposite corner nodes might be the sum of two individual routes from node 1. The route between node 3 and node 22 might be 3-2-10-9-1-23-21-25-22 through node 1; it will take more than an hour for a 20.1 km (=9.8 + 10.3) long route. Routes for opposite end nodes might be possible, avoiding node 1, and in some cases, the route might be shorter than through node 1.