Use [collections.defaultdict(list)][1] to store your data:

    import arcpy, collections
    
    fc = r'C:\data.gdb\somefeatureclass' #Or shapefile
    fields = ['Road_Name','X','Y']
    
    d = collections.defaultdict(list)
    
    with arcpy.da.SearchCursor(fc,fields) as cursor:
        for roadname,x,y in cursor:
            d[roadname].append([x,y])

Key will be roadname and values will be a list of lists of coordinate pairs. For example if you do:

    d['Washington street']

you will get:

    [[1,2],[1,4],...]
and the 21 remaining coordinate pairs.

Your next step will perhaps be to iterate over keys and values, see this question: [Iterating over key and value of defaultdict dictionaries][2]


  [1]: https://docs.python.org/2/library/collections.html#defaultdict-examples
  [2]: https://stackoverflow.com/questions/2768188/iterating-over-key-and-value-of-defaultdict-dictionaries