Calculations across multiple columns based on non-blanks

Dear Experts,

Help please! Thank you in advance.

In the spreadsheet attached:

Row 1 notes different tram numbers

Column A notes distance travelled.

Columns B onwards has "1"s in rows noting where failures have occurred at corresponding distances, as per Column A.

I want to calculate the deltas only between the "1"s in each column. For example, in Column B there are four "1"s.  There should be 3 corresponding deltas.  Is there a way to do this, using arrays perhaps?

Many thanks.