Repairs to Civil Structures

Under the category " Commercial and Industrial Construction Service" not only services with regard to new construction but also in connection with repair to old Civil Structure are taxable. Clause (b) of Section 65(25b) of Finance act, 2005 provides that repair of civil structure is taxable under the category " Commercial and Industrial Construction Service" . But services provided in respect of road and bridges ( new construction as well as repairs ) are specifically excluded from the perview of taxability under  this category. Does it mean that these services are not taxable at all or are not taxable under these categories? If the repairs of roads or bridges are taxable under Management , Maintenance and repairs shall it not be violation of  the principle to exempt a particular activity under one category and tax  the same under the other?