Opinion by
Me. Justice Eagen,The wife-plaintiff, Lena Cuthbert, fell and was injured while crossing a public street in the city of Philadelphia. An action for injuries on behalf of herself and her husband against the municipality and the Philadelphia Transportation Company followed. A jury returned a verdict against both defendants and awarded the husband $25,000 and the wife $15,000. Motions for judgment notwithstanding the verdict or a new trial were denied, although the court below did reduce the husband’s award, through an order of remittitur, to $10,000. Both defendants appealed.
Viewing the evidence in the light most favorable to the plaintiffs, the facts are these: The accident here involved occurred at 12:55 o’clock p.m. on January 17, 1958. The wife-plaintiff, accompanied by her sister, was going from her home in Philadelphia to that of her sister, also in the same city. Alighting from a public conveyance at the corner of Germantown Avenue and Oxford Street, the two women proceeded, with Mrs. *612Cuthbert on the curb-side of her sister, east along the north sidewalk of Oxford Street (a one way street with traffic allowed only from a west to east direction) until, after “some distance,” they arrived at the “T”type intersection of Oxford Street and 3d Street (also a one-way street with traffic allowed only from south to north), an uncontrolled intersection.
In the middle of each of these two streets are trolley rails which, by means of curved sections, swing from Oxford Street onto 3d Street. Along the inner side of the easternmost rail of part of this curved section was a depression in the street 3 to á inches in depth and 6 1/2 feet in length, characterized by witnesses for the city as a “tripping defect,” which defect had existed for a period of at least two years prior to the time of the present incident. Of the length of this depression, 18 inches lay south of the north line of the crosswalk (i.e., within the area of the crosswalk) across 3d Street, an area delimited by extensions of the north building line and north curb line of Oxford Street, and 5 feet lay north of the north line of the crosswalk. The evidence also indicated that there was a metal manhole cover lying between the said trolley rails some 3 feet north of the north line of the crosswalk.
Having to cross this intersection in their journey to the sister’s home, Mrs. Cuthbert testified that she casually glanced into the intersection and then looked over her right shoulder to determine whether any traffic was proceeding toward them. Seeing no moving traffic, the two women proceeded to cross the intersection. At this point the traffic control lights at the intersection of Germantown Avenue and Oxford Street changed, and Mrs. Cuthbert, hearing the screech of auto tires, became frightened. One car swung in an arc in front of her and then another swung behind her. Hurrying to complete crossing the street, Mrs. Cuthbert tripped and fell, causing the injuries for which this *613suit was instituted. Mrs. Cuthbert testified that before she fell her foot “got caught in the hole by the rail.” She also stated she “knew” she had tripped over the depression, described hereinbefore, and identifed this depression on a photographic exhibit. Admittedly, however, she did not see the depression before she tripped, nor immediately thereafter. The first time she saw the depression was at a point of time after she had gone to the hospital for medical attention and returned to “see what it was” that had caused her to fall. (Emphasis added.) She could not, or at least did not, identify the exact portion of the crosswalk (shown by other uncontradicted testimony to be 144 inches wide), upon which she was walking at or before the time of the accident. However, she did state that she and her sister were walking upon the crosswalk together in a straight line, with her sister on the house or north side thereof, and her on the curb-line side. In this connection, it should be noted that the depression extended into the crosswalk for a distance of only 18 inches on the north side thereof.
The determinative issue raised on this appeal by appellant-city is whether or not the plaintiffs failed in their evidence to prove that the defect here involved was the proximate cause of the injuries suffered. We agree that the plaintiffs did not so prove. This issue thus becomes determinative of both appeals. Plaintiffs having failed to prove proximate cause as a matter of law, the case should never have been submitted to the jury (Idlette v. Tracey, 407 Pa. 278, 180 A. 2d 37 (1962)), or judgment n.o.v. should have been entered in favor of both defendants.
We think it is clear that either one or the other of the appellants, not at this time determining which one, was negligent in allowing this defect — 6 1/2 feet long and 3 to 4 inches in depth — to lie unattended for a period in excess of two years. Granting that neither the *614city nor PTC had any greater duty than to maintain this area in a condition reasonably free from irregularities and defects (See, Bosack v. Pittsburgh Rys. Co., 410 Pa. 558, 189 A. 2d 877 (1963), and cases cited therein), even the city’s witness characterized this as a “tripping defect” which should have had immediate attention. Considering the particular character of the defect and the testimony of the parties in regard thereto, we cannot say, as a matter of law, that allowing this defect to exist for a two-year period did not constitute actionable negligence. Consequently, the court below properly left this question to be determined by the jury.
Nevertheless, it remains a principle so fundamental as to require no authority that the mere existence of negligence and the occurrence of injury are insufficient to impose liability upon anyone. There remains to be proved the vitally important link of causation: Flagiello v. Crilly, 409 Pa. 389, 187 A. 2d 289 (1963) ; Harrison v. Pittsburgh, 353 Pa. 22, 44 A. 2d 273 (1945); Philadelphia & R. R. Co. v. Spearen, 47 Pa. 300 (1864); Drill v. Genetti, 200 Pa. Superior Ct. 471, 190 A. 2d 185 (1963); and, Hillelson v. Renner, 183 Pa. Superior Ct. 148, 130 A. 2d 212 (1957). And plaintiff has the burden of proving this link, that the defendant’s negligence was the proximate cause of her injury: Cushey v. Plunkard, 413 Pa. 116, 196 A. 2d 295 (1964); Loeb v. Allegheny County, 394 Pa. 433, 147 A. 2d 336 (1959); or of proving evidence from which a reasonable inference arises that the defendant’s negligence was the proximate cause of the injury: Zilka v. Sanctis Construction, Inc., 409 Pa. 396, 186 A. 2d 897 (1962). On the other hand, it is not necessary that plaintiff prove with mathematical exactness that the accident could only have been caused in one manner to the exclusion of all other possibilities (Finney v. G. C. Murphy Co., 406 Pa. 555, 178 A. 2d 719 (1962)), but he must elimi*615nate those other causes, if any, as were fairly suggested by the evidence: Lescznski v. Pittsburgh Rys. Co., 409 Pa. 102, 185 A. 2d 538 (1962); Foley v. Pittsburgh Des Moines Co., 363 Pa. 1, 68 A. 2d 517 (1949); Stauffer v. Railway Express Agency, Inc., 355 Pa. 24, 47 A. 2d 817 (1946); Cohen v. Penn Fruit Co., 192 Pa. Superior Ct. 244, 159 A. 2d 558 (1960). And it is the duty of the trial court to determine whether or not this requirement has been met in the first instance before the issue can be submitted to the jury: Idlette v. Tracey, supra.
In this regard, all that the evidence shows is that upon undertaking to cross the intersection, plaintiff was threatened by approaching vehicles, became frightened, and tripped, serious injuries being caused by the fall. Mrs. Cuthbert was asked specifically on direct examination by her own counsel whether she ever saw the defect which is alleged to have tripped her. In response, she said that she had not seen the defect when she stood on the northwest corner of the intersection, while she was crossing the intersection, nor after she had tripped. She testified that the first time she saw the defect was upon her return, obviously some time later, from the hospital after having received medical attention for her injuries. The only eyewitness other than Mrs. Cuthbert, her sister, was not called upon to testify as to whether or not she had seen the defect. While, during this direct examination, Mrs. Cuthbert testified that at the time she fell and thereafter, she “knew” that it was into this defect which she fell and identified it on an exhibit, there was absolutely no evidentiary fact upon which this conjecture could have been based, nor upon which the jury could have weighed it. The jury may not be permitted to reach its verdict on the basis of speculation or conjecture; there must be evidence upon which its conclusion may be logically based: Smith v. Bell Telephone Co. of Pa., *616397 Pa. 134, 153 A. 2d 477 (1959); Schofield v. King, 388 Pa. 132, 130 A. 2d 93 (1957).
Mrs. Cuthbert may very well have fallen into the defect as she alleged, but she has failed to prove any facts upon which a jury would have been justified in so finding. It is equally possible that she tripped over a properly maintained section of the trolley rail for which, while unfortunate, no liability would have attached. Under her own testimony, the depression was not in her path as she traversed the crosswalk, but rather on that portion thereof upon which her sister was walking.
Appellees distinguish Reddington v. Philadelphia, 253 Pa. 390, 98 A. 601 (1916), on the basis that there the plaintiff could not testify as to what had caused her to fall, but that here Mrs. Cuthbert positively stated that she “knew” that the defect had caused her to fall. But, as above pointed out, this was an improper conjecture, without basis in proven facts, and as a result, it rises no higher than plaintiff’s inability to testify in Reddington, supra. On this point, we feel that Reddington, supra, is exactly apposite. Even further, in that case there was no evidence of other possible tripping objects lying about, as is the case here. See also, Freund v. Hyman, 377 Pa. 35, 103 A. 2d 658 (1954). Nonetheless, the court held in both of those cases that there was no evidence which would justify a jury in finding that the defect, alleged to have caused the injury, did in fact do so.
Plaintiffs having failed to prove that the defect along the trolley rail was the proximate cause of wife-plaintiff’s injuries, the judgments cannot stand.
In view of our conclusion on the question of causation, it is unnecessary to discuss the question of contributory negligence.
Judgments reversed and here entered for both defendants.