, good evening.
There is a system, can I suggest you have a look @ "Soda Blasting" ?
It is similar to "Sand blasting" but the soda is a load softer and tends not to remove the surface, the Soda removes the paint.
The draw back ?? there is a down side, that is the mess left, so not a good solution on [say] a main street??
On this Forum someone noted that there is Dry Ice blasting, that will leave only paint residue and water.
The machinery involved can I believe be hired as well as all the consumables, not sure about Dry Ice that stuff needs careful handling.
Draw back with using chemicals is keeping the chemicals out of any water course.