my %pointdata;
my @chunkends;
for ( my $i=0; $i<@data; $i++ ) # road-chunks
{
  for ( my $j=0; $j<@{$data[$i]; $j++ ) # points in a chunk
  {
    my $key = join(",",$data[$i][$j]->{X},$data[$i][$j]->{Y});
    push @{$pointdata{$key}}, sprintf("%5.5d:%5.5d",$i,$j);
    $chunkends[$i] = $key if ( $j == 0 );
  }
  $chunkends[$i] .= "-$key";
}
# Now the %pointdata array contains all the information
# about junctures between chunks (these not necessarily 
# all end-point junctures -- perhaps some road chunks could
# intersect at the mid-points?)  Also, the @chunkends array
# cites the %pointdata keys for the endpoints of each chunk;
# if you only want to find end-point junctures, identify the
# %pointdata keys with multi-element entries and grep for
# each one among the strings in @chunkends.