
<TABLE> <S> <C>




<ARTICLE> 5
<MULTIPLIER> 1,000
       
<S>                             <C>
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>               DEC-31-1998
<PERIOD-START>                  JAN-01-1998
<PERIOD-END>                    JUN-30-1998
<CASH>                                16,922
<SECURITIES>                               0
<RECEIVABLES>                        320,988
<ALLOWANCES>                          10,290
<INVENTORY>                           39,689
<CURRENT-ASSETS>                     411,894
<PP&E>                             1,941,264
<DEPRECIATION>                       991,847
<TOTAL-ASSETS>                     1,397,179
<CURRENT-LIABILITIES>                292,328
<BONDS>                              222,892
<PREFERRED-MANDATORY>                      0
<PREFERRED>                                0
<COMMON>                              50,777
<OTHER-SE>                           689,315
<TOTAL-LIABILITY-AND-EQUITY>       1,397,179
<SALES>                                    0
<TOTAL-REVENUES>                   1,514,330
<CGS>                                      0
<TOTAL-COSTS>                      1,397,907
<OTHER-EXPENSES>                           0
<LOSS-PROVISION>                           0
<INTEREST-EXPENSE>                     6,876
<INCOME-PRETAX>                      109,547
<INCOME-TAX>                          43,360
<INCOME-CONTINUING>                   66,187
<DISCONTINUED>                             0
<EXTRAORDINARY>                            0
<CHANGES>                                  0
<NET-INCOME>                          66,187
<EPS-PRIMARY>                           1.32<F1>
<EPS-DILUTED>                           1.29<F2>
<FN>
<F1>EARNINGS PER SHARE - BASIC (IN COMPLIANCE WITH SFAS 128)
<F2>EARNINGS PER SHARE - DILUTED (IN COMPLIANCE WITH SFAS 128)
</FN>
        


</TABLE>
