
<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM CONSOLIDATED
BALANCE SHEETS CONSOLIDATED STATEMENTS OF INCOME AND IS QUALIFIED IN ITS
ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
<CURRENCY> US DOLLARS
       
<S>                             <C>
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1997
<PERIOD-START>                             JAN-01-1997
<PERIOD-END>                               JUN-30-1997
<EXCHANGE-RATE>                                      1
<CASH>                                          10,187
<SECURITIES>                                         0
<RECEIVABLES>                                   28,161
<ALLOWANCES>                                   (1,539)
<INVENTORY>                                          0
<CURRENT-ASSETS>                                72,375
<PP&E>                                         101,599
<DEPRECIATION>                                (50,976)
<TOTAL-ASSETS>                                 155,187
<CURRENT-LIABILITIES>                           56,538
<BONDS>                                         33,000
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                           184
<OTHER-SE>                                      58,327
<TOTAL-LIABILITY-AND-EQUITY>                   155,187
<SALES>                                              0
<TOTAL-REVENUES>                               134,234
<CGS>                                                0
<TOTAL-COSTS>                                  110,416
<OTHER-EXPENSES>                                 6,584
<LOSS-PROVISION>                                   189
<INTEREST-EXPENSE>                                 665
<INCOME-PRETAX>                                 16,569
<INCOME-TAX>                                     6,627
<INCOME-CONTINUING>                              9,942
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                     9,942
<EPS-PRIMARY>                                      .52
<EPS-DILUTED>                                      .52
        

</TABLE>
