
<TABLE> <S> <C>

<ARTICLE>                                          5
<MULTIPLIER>                                       1000
       
<S>                                                <C>
<PERIOD-TYPE>                                      6-MOS
<FISCAL-YEAR-END>                                  DEC-31-1996
<PERIOD-END>                                       JUN-30-1997
<CASH>                                             41,367
<SECURITIES>                                       0
<RECEIVABLES>                                      276,637
<ALLOWANCES>                                       12,277
<INVENTORY>                                        26,542
<CURRENT-ASSETS>                                   422,898
<PP&E>                                             2,259,793
<DEPRECIATION>                                     767,797
<TOTAL-ASSETS>                                     2,055,140
<CURRENT-LIABILITIES>                              512,211
<BONDS>                                            417,075
<PREFERRED-MANDATORY>                              0
<PREFERRED>                                        0
<COMMON>                                           204,362
<OTHER-SE>                                         516,247
<TOTAL-LIABILITY-AND-EQUITY>                       2,055,140
<SALES>                                            953,335
<TOTAL-REVENUES>                                   953,335
<CGS>                                              0
<TOTAL-COSTS>                                      905,915
<OTHER-EXPENSES>                                   0
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<INTEREST-EXPENSE>                                 22,432
<INCOME-PRETAX>                                    28,401
<INCOME-TAX>                                       9,874
<INCOME-CONTINUING>                                18,527
<DISCONTINUED>                                     0
<EXTRAORDINARY>                                    0
<CHANGES>                                          0
<NET-INCOME>                                       18,527
<EPS-PRIMARY>                                      0.52
<EPS-DILUTED>                                      0.52
        


</TABLE>
