(concurring in result) For the reasons stated by the majority I agree that the exceptions should be sustained. The cost in 1962 of reproducing a structure erected in 1889, which admittedly never would be reproduced, is obviously irrelevant and confusing as a factor in determining the damages sustained by the taking.
The majority suggest, however, that the cost of a suitable replacement structure may be considered by an expert in forming an opinion of the residual value of the old armory. This, it seems to me, would be equally irrelevant and confusing. The Commonwealth’s evidence shows that a suitable replacement, which would necessarily require a different locus, would involve the construction of a modern school-type building with gymnasium, a parking area (for military and civilian vehicles),.a helicopter landing area *152and other features, none of which were present on the land taken. The dissimilarity is so gross as to make replacement cost patently absurd as a guide in reaching an opinion of the residual value of the old armory at the time of the taking. The replacement cost, like the reproduction cost, would result in a blizzard of figures irrelevant to the simple question to be resolved. The Commonwealth’s evidence tends to show that the old armory, by obsolescence, had become so ill adapted to modern needs that its value as a special purpose structure had attenuated almost to the vanishing point.1 This being so, I see no reason for applying any special rule for the determination of damages. Mathematical certainty is not always possible. We should require, however, the application of a sensible and understandable rule to enable the jury to reach a just result. The familiar and fundamental rule for the assessment of damages in eminent domain cases (the fair market value of the property taken, at the time of the taking) contemplates compensation to the owner for the residual useful value which the structure may contribute to the land, “taking into consideration all uses to which the land was adapted and might in reason be applied.” Nichols, Eminent Domain (Rev. 3d ed.) § 12.2 (1). Providence & Worcester R.R. v. Worcester, 155 Mass. 35, 42. Teele v. Boston, 165 Mass. 88, 92. Tigar v. Mystic River Bridge Authy. 329 Mass. 514, 517. On the Commonwealth’s evidence, it would seem that the application of the general rule would more nearly accomplish a just result than would an exceptional rule which would give free rein to the sometimes fanciful theories of experts.
Expert opinion testimony doubtless will be necessary to establish the fair market value of the property at the time of the taking. Although the admissible range of supporting data for the expert’s opinion rests mainly in the discretion of the judge, it should not, I submit, extend to the estimated cost of a replacement structure.
Statute 1962, c. 717, shows that the Commonwealth then contemplated the erection of a new armory by providing that the funds received from the Massachusetts Turnpike Authority be used, in addition to an amount already appropriated and to available Federal funds, for the acquisition of land and for the erection of a replacement armory with facilities.