13.6 kilometers.

1. First start from Dushu Lake Neighborhood Center and go 323 meters to Bada Street, then drive 3.7 kilometers on Xinghu Street.

2. Next, drive 4.4 kilometers through the Dushu Lake Tunnel and reach 440 meters along the Dushu Lake Avenue auxiliary road.

3. Then continue driving on the Xinggang Street auxiliary road for 1.5 kilometers to reach 285 meters of Xingrong Street and reach the end point, Suzhou Center.