That's a debatable point.
Criminal damage occurs when a person without lawful excuse destroys or damages property belonging to another, attempting to destroy or damage property, or is reckless as to whether such property is destroyed or damaged.
I would contend that it is not reckless to attempt to continue to walk lawfully along a footway, probably far less reckless than walking jn a live road to by pass such an unlawful obstruction. So, provided you don't do it with intent to cause damage (Google mens rea - its a lengthy subject on its own) and take a reasonable degree of care not to do so then any subsequent damage would not meet the definition, technically no crime.
There is the occasional stated case here and there in similar circumstances and people have got away with in court.