The commissioner or his agent may enter upon private property for the purpose of conducting surveys, inspections or geological investigations for the location, relocation, construction or reconstruction of any proposed or existing highway. After giving reasonable notice to the property owner or owners affected, he or his agent may also enter private property for the purpose of performing borings, soundings or other tests required to accomplish any of the foregoing objectives with respect to such highways. He shall use care so that no unnecessary damage shall result, and the state shall pay damages to the owner of any property from appropriations made to the Department of Transportation for any damage or injury he causes such owner by such entrance and use. If entry to any property for the purpose of performing borings, soundings or other tests is refused to the commissioner or his agent after he has given reasonable notice to the owner or owners thereof, the commissioner shall assess damages in the manner provided by statute for the taking of land for highway purposes, and, at any time after such assessment has been made by said commissioner, may enter said property for the purpose of performing borings, soundings or other tests. If the owner accepts such assessment of damages, he shall notify the commissioner in writing, and said commissioner shall pay such sum to said owner within thirty days or, after the expiration of said thirty days, shall pay such sum with interest at six per cent. If the owner is aggrieved by such assessment, he shall notify the commissioner in writing and may appeal to any court within its jurisdiction for a reassessment of such damages within six months from the date said commissioner forwarded such assessment to such owner. This section shall not limit or modify rights of entry upon property otherwise provided for by law.