There is considerable debate about the exact meaning of Waibaidu (外白渡), the name given to the wooden bridge erected by the Shanghai Municipal Council in 1873.
According to one source, "The upper stream of any river was called li 裡 (internal, inside); the lower stream was called “wai”."
Xue Liyong (薛理勇), indicates in his book on the history of the Bund:
In several cases, the Chinese used the terms li 裡 (internal) and wai 外 (external) to indicate the greater (nei) or lesser (wai) degree of proximity of a location.
There was even an intermediate degree with the use of zhong 中 (middle) for places located between these two extremes.
There remains several place names in Shanghai that are linked to this practice.
The Chinese name of the Garden Bridge – waibaidu qiao 外白渡橋 – is such a case.
The name makes sense only in relation with another bridge called libaidu qiao 裡白渡橋 that was located further inside the Soochow Creek, whereas the Garden Bridge was located at the mouth of the creek where it merges into the Huangpu river.

Another source indicates that in Shanghainese, waibaidu means passing through the bridge without paying.
Because there was no longer any toll collected to cross the bridge, it began to be called Waibaidu, but "whereas the old name meant 'foreigners/outer ferry crossing bridge' the character bai was changed to a homophonic that altered the meaning to 'outer free crossing bridge'".
There is considerable debate about the exact meaning of Waibaidu (外白渡), the name given to the wooden bridge erected by the Shanghai Municipal Council in 1873. According to one source, "The upper stream of any river was called li 裡 (internal, inside); the lower stream was called “wai”." Xue Liyong (薛理勇), indicates in his book on the history of the Bund:
In several cases, the Chinese used the terms li 裡 (internal) and wai 外 (external) to indicate the greater (nei) or lesser (wai) degree of proximity of a location. There was even an intermediate degree with the use of zhong 中 (middle) for places located between these two extremes. There remains several place names in Shanghai that are linked to this practice. The Chinese name of the Garden Bridge – waibaidu qiao 外白渡橋 – is such a case. The name makes sense only in relation with another bridge called libaidu qiao 裡白渡橋 that was located further inside the Soochow Creek, whereas the Garden Bridge was located at the mouth of the creek where it merges into the Huangpu river.
Another source indicates that in Shanghainese, waibaidu means passing through the bridge without paying. Because there was no longer any toll collected to cross the bridge, it began to be called Waibaidu, but "whereas the old name meant 'foreigners/outer ferry crossing bridge' the character bai was changed to a homophonic that altered the meaning to 'outer free crossing bridge'".
Waibaidu Bridge