<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<RESTATED> 
<MULTIPLIER> 1,000
       
<S>                             <C>                     <C>                     <C>
<PERIOD-TYPE>                   3-MOS                   3-MOS                   3-MOS
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1997             DEC-31-1997
<PERIOD-START>                             JAN-01-1997             APR-01-1997             JUL-01-1997
<PERIOD-END>                               MAR-31-1997             JUN-30-1997             SEP-30-1997
<CASH>                                          60,416                  34,436                  20,070
<SECURITIES>                                         0                       0                       0
<RECEIVABLES>                                   21,919                  22,470                  23,341
<ALLOWANCES>                                     (806)                 (1,000)                   (705)
<INVENTORY>                                          0                       0                       0
<CURRENT-ASSETS>                                84,017                  62,387                  46,012
<PP&E>                                         256,536                 280,326                 304,157
<DEPRECIATION>                                (77,999)                (86,710)                (96,358)
<TOTAL-ASSETS>                                 274,921                 268,799                 266,064
<CURRENT-LIABILITIES>                           23,403                  22,128                  24,321
<BONDS>                                        179,304                 179,454                 179,460
<PREFERRED-MANDATORY>                                0                       0                       0
<PREFERRED>                                          0                       0                       0
<COMMON>                                           111                     112                     114
<OTHER-SE>                                      68,827                  63,200                  58,206
<TOTAL-LIABILITY-AND-EQUITY>                   274,921                 268,799                 266,064
<SALES>                                         29,656                  33,132                  36,692
<TOTAL-REVENUES>                                29,656                  33,132                  36,692
<CGS>                                           12,817                  14,338                  15,731
<TOTAL-COSTS>                                   19,444                  20,228                  21,362
<OTHER-EXPENSES>                                     0                       0                       0
<LOSS-PROVISION>                                     0                       0                       0
<INTEREST-EXPENSE>                               4,064                   4,302                   4,638
<INCOME-PRETAX>                                (6,669)                 (5,736)                 (5,039)
<INCOME-TAX>                                        10                      20                      11
<INCOME-CONTINUING>                            (6,679)                 (5,756)                 (5,050)
<DISCONTINUED>                                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0
<CHANGES>                                            0                       0                       0
<NET-INCOME>                                   (6,679)                 (5,756)                 (5,050)
<EPS-PRIMARY>                                    (.60)                   (.51)                   (.45)
<EPS-DILUTED>                                        0                       0                       0
        

</TABLE>