public int getRoadNumber(){
        int number=0;
        String requete= "select count(*) from road";
        try {
            Statement statement = MyConnection.getInstance().createStatement();
            ResultSet resultat = statement.executeQuery(requete);
            while(resultat.next()){
                number=resultat.getInt(1);
            }
        } catch (SQLException ex) {
            System.out.println("Error in road statistics "+ex.getMessage());
        }
        return number;
    }