I believe that using cells connected both by top and bottom flanges ( closed cells) is better than cells connected by top flanges only. This is because of the higher torsional rigidity of the closed box sections over the other type.

Dear Abbas

When the depth of a box girder bridge exceeds 1/6 or 1/5 of the bridge

width, it is recommended to be designed as a single cell box girder bridge.However, if the bridge depth is smaller than 1/6 of the bridge width, then a twin-cell or multiple cell is a better choice

Thanks Dr Ayad and Dr Amjad for your valuable answers.