<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
CONSOLIDATED FINANCIAL STATEMENTS AS OF AND FOR THE SIX MONTHS ENDED JUNE 30,
1998 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FORM 10-Q FOR THE
QUARTERLY PERIOD ENDED JUNE 30, 1998.
</LEGEND>
<MULTIPLIER> 1,000
       
                             
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-START>                             JAN-01-1998
<PERIOD-END>                               JUN-30-1998
<CASH>                                           8,461
<SECURITIES>                                         0
<RECEIVABLES>                                  162,494
<ALLOWANCES>                                    18,384
<INVENTORY>                                          0
<CURRENT-ASSETS>                               177,114
<PP&E>                                         714,565
<DEPRECIATION>                                 154,455
<TOTAL-ASSETS>                                 972,255
<CURRENT-LIABILITIES>                          138,341
<BONDS>                                        282,497
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                           492
<OTHER-SE>                                     462,404
<TOTAL-LIABILITY-AND-EQUITY>                   972,255
<SALES>                                              0
<TOTAL-REVENUES>                               456,278
<CGS>                                                0
<TOTAL-COSTS>                                  354,864
<OTHER-EXPENSES>                                19,642
<LOSS-PROVISION>                                 2,576
<INTEREST-EXPENSE>                                   0
<INCOME-PRETAX>                                 57,315
<INCOME-TAX>                                    17,596
<INCOME-CONTINUING>                             39,719
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                    39,719
<EPS-PRIMARY>                                      .89
<EPS-DILUTED>                                      .86