The provisions of this Article shall not prevent the Department of Transportation and the owner from entering into a written agreement whereby the owner agrees and consents that the Department of Transportation may enter upon his property without filing the complaint and declaration of taking and depositing estimated compensation as herein provided and the Department of Transportation shall have the same rights under such agreement with the owner in carrying on work on such project as it would have by having filed a complaint and a declaration of taking and having deposited estimated compensation as provided in this Article. (1959, c. 1025, s. 2; 1961, c. 1084, s. 8; 1973, c. 507, s. 5; 1977, c. 464, s. 7.1.)