So you have some participants twice in the data set, some only

once. I am not sure how to deal with such situations properly.

If each of the observations was from a different subject AND you

could break down your research question(s) to binary ones

(e.g. effect of the intervention on whether someone did street

parking yes/no), then a binary logistic regression could be

used, with 3 predictors: when was the observation (before/after),

where was the observation (experimental area/control area),

and the interaction of these two. The interaction would tell you

whether the before-after difference was different between areas.

But I don't know how the test results are affected by the fact

that not all observations are from different subjects. Maybe someone

else here has an idea.

With kind regards

K.