This matter arose out of a personal injury action instituted by appellee, Mary Cooper, against the District of Columbia as the result of a fall she sustained on a walkway located within the confines of the Lorton Reformatory. A jury trial was had at which appellee posited that her fall and resultant injuries were proximately caused by the District’s negligent failure to maintain the walkway in a reasonably safe condition. Following the denial of the District’s motions for a directed verdict at the close of appellee’s case, and again at the close of all the evidence, the case was submitted to the jury which returned a verdict of $30,000 in favor of appellee. Judgment was entered in accordance therewith. Appellant’s subsequent motion for a judgment non obstante veredicto having been denied, this appeal was taken.1 On appeal, we are presented with one question: whether there was sufficient evidence to support the jury’s conclusion that the District of Columbia, by any negligent act or failure to act, proximately caused injury to appellee.2 We find that the jury verdict is supported by sufficient evidence and therefore affirm.
I
At approximately 7:00 p. m. on March 9, 1977, Mary Cooper and a companion, Frances Fuller, arrived at the Lorton Reformatory for the purpose of visiting an inmate. Having been “processed” at the visitors’ trailer, the two women emerged from the trailer onto a brick walkway. The walkway was the only route which led to the visitors’ lounge. Cooper testified that she took approximately two steps along the walkway, “left level ground and went to unlevel ground.” In doing so, she fell on a portion of the walkway where the bricks had been removed and replaced with material largely composed of dirt, sand, and little rocks. *654She landed on her knees striking her forehead on the sand compound. Appellee stated that the portion of the walkway which contained the sand was not equal in height to the level of the brick walkway, but was lower. Although she was not sure of the exact difference in elevation, she was positive that the sand base was lower than the bricks. When asked on cross-examination to give the specific dimensions, Cooper stated that there was a difference of an eighth of an inch in the surface level. Appellee saw no signs warning of the irregularity, nor was she given a verbal warning. Assisted by Fuller and Lieutenant James A. Meyer, a correctional supervisor at Lorton, who observed the fall, appellee got to her feet. At that time she declined Meyer’s offer of medical assistance. She decided instead to proceed to the visitors’ lounge. Once there, however, dizziness caused her to abbreviate her visit and return to the visitors’ trailer. Appellee then attempted to get medical assistance but was informed that she could not be taken to the Reformatory infirmary at that time; she was advised to see her personal physician.
The testimony of Frances Fuller was substantially the same as appellee’s. She testified that she almost tripped in the same area. She turned to warn appellee, only to see her fall. She added that no signs were posted, nor was she given any warning by any Lorton employee.
William Dawson, a bricklayer employed at Lorton, testified on behalf of the District. He recalled that in early March 1977, cold weather caused water underneath some of the bricks in the walkway to freeze and buckle in an area approximately four feet wide and six feet long. Dawson was called to repair the walkway but was unable to replace the bricks because the subzero temperature would cause the mortar to freeze before the bricks could be reset. As a temporary measure, he filled the area (where the bricks had been removed) with sand which he “tapped down” and leveled with the remaining bricks. He returned once a day to inspect the area and make sure that the sand was level with the adjacent bricks. Dawson testified that, in light of the inclement weather, this was one of the few things that could be done to make the walkway safe. He further testified that on the day of appellee’s fall, he inspected the walkway at approximately 2:00 or 3:00 p. m. At that time, the sand was level with surrounding bricks.
Lieutenant James A. Meyer testified that while on duty at the walkway leading from the visitors’ trailer to the prison, on March 7, 1977, he observed appellee and Fuller exit from the visitors’ trailer at approximately 7:16 p. m. He observed appellee trip and fall, landing on her palms and knees. Meyer testified that he did not see appellee’s head strike the ground. Upon witnessing the fall, Meyer rushed to appellee and assisted her to her feet. Once on her feet, she declined the medical treatment which was offered. After the lieutenant obtained the information needed for an accident report, appellee proceeded to the visiting hall. As she walked to the hall, Meyer observed nothing out of the ordinary. The witness also testified that, at the time of the fall, the sand in the area under repair was level with the surrounding bricks. It was illuminated by a light on a twelve foot pole.
Captain Joseph S. Mastín, the shift supervisor, was stationed with Lieutenant Meyer at the entrance to the visitors’ lounge. Mastín did not observe appellee fall, nor did he converse with her. He did, however, observe appellee as she rose to her feet and moved to the visiting hall. He noticed nothing unusual as she did so. Mastín was also present when appellee left the institution. He testified that as Cooper was departing, he heard Sergeant Nelson offer her the same medical treatment which Meyer had previously offered. Again she declined. According to Mastín, approximately 150 to 200 people passed through the trailer (and over the walkway) on an average night during visiting hours.
Lastly, Sergeant Harold S. Nelson testified that he processed appellee into Lorton on that particular evening, but did not see her fall. Nelson did see her again at 9:00 p. m. at the close of visiting hours. At that *655time, he noticed that appellee was walking with an unusual gait. He made inquiry and upon being told by appellee that she had fallen, Nelson “insisted” that she see the medical technician who was on duty. She declined to do so, stating that her leg felt “all right” and that she would soak it when she got home.
Sergeant Nelson was charged with the responsibility of inspecting the visitors’ trailer and gate area for safety and health violations. On the night of the accident, when Nelson came on duty, he noticed that some bricks in the walkway had been taken up and replaced with sand. He testified that the sand was “up to the surface of the remaining bricks and the borders and it was packed.” At approximately 9:00 p. m., when visiting hours ended, it was his opinion that the walkway was in the same condition. If the sand was not level with the surrounding bricks, it would have been Nelson’s responsibility to report that or prevent visitors from entering the institution until the walkway was properly repaired. Nelson estimated that 200 people were processed between 5:00 p. m. and 9:00 p. m. on March 9, 1977 at the checkpoint at which appellee was processed, and the same number entered the institution via the walkway on which she fell. The sergeant received no other accident report concerning the walkway during that time.
II
We start with the premise that the District is not an insurer of the safety of those who utilize its streets and sidewalks. It is, however, required to maintain the same in a reasonably safe condition. Washington Gas Light Co. v. Jones, D.C. App., 332 A.2d 358, 361 (1975); District of Columbia v. Williams, D.C.Mun.App., 46 A.2d 111, 112 (1946). The question of whether a walkway is reasonably safe is generally one for the jury. Only in extreme instances where no reasonable person could reach a verdict in favor of the plaintiff on the evidence presented, should a directed verdict be granted, Proctor v. District of Columbia, D.C.App., 273 A.2d 656, 659 (1971), and only in such cases is a judgment non obstante veredicto proper.3 For, jurors are the triers of fact and where there is evidence upon which reasonable persons might differ as to negligence and other elements of liability, those questions must be decided by the jury. Id.; Shewmaker v. Capital Transit Co., 79 U.S.App.D.C. 102, 103, 143 F.2d 142, 143 (1944).
The plaintiff has the burden of establishing that a violation of the reasonable standard of care is the proximate cause of the injury sustained. The mere happening of an accident does not meet this burden. See Jones v. Safeway Stores, Inc., D.C.App., 314 A.2d 459, 460 (1974). There must be evidence of the violation and injuries proximately caused thereby. However, “the law does not require proof of negligence to a certainty. Rather, the law requires only that the evidence, when viewed most favorably for the plaintiff, indicate a reasonable probability of negligence on the part of the defendant.” Rich v. District of Columbia, D.C.App., 410 A.2d 528, 532 (1979) (citation omitted).
Viewing the evidence in the light most favorable to appellee, id., we find sufficient evidence on this record from which a reasonable person could conclude that the District failed to maintain the walkway in a reasonably safe condition and that its failure to do so proximately caused appellee’s injuries.
Relying primarily on Proctor v. District of Columbia, supra, appellant argues that appellee’s evidence was insufficient to go to the jury. In Proctor, the plaintiff, while en route home from a neighborhood store at about 10:00 p. m., stubbed her toe on what she described as a “protruding brick” in a brick sidewalk, and fell to the ground, fracturing her arm. By measuring the distance *656between the two fingers which plaintiff held up to depict the difference in the elevation of brick over which she tripped and the surrounding bricks, the trial court determined that there was a one-quarter inch difference. On those facts this court examined whether there was sufficient evidence to raise a factual question to be presented to the jury. Inasmuch as the only evidence of negligence offered by the plaintiff was a brick protruding one-quarter of an inch, we agreed with the trial judge that “no reasonable men [could] differ regarding the condition of the surface at the point where plaintiff said she tripped and fell.” Id. at 658 (footnote omitted). Thus, taking into consideration the frequency with which pedestrians in urban areas witness minor elevations in the sidewalks, the plaintiff’s failure to offer evidence of negligence other than the height of the protruding brick, and the minor nature of that protrusion, we affirmed the trial court’s decision, concluding as a matter of law that the evidence could not support a finding of negligence.
Appellant argues by analogy that in this case, the one-eighth inch4 irregularity was likewise so trivial that a directed verdict or judgment non obstante veredicto should have been granted. We are not persuaded by this argument since, in the instant case, the evidence of negligence is not a mere minor differential in the elevation of bricks in a brick sidewalk, but an area of known irregularity in a walkway, where the jury reasonably could infer that the temporary walkway area was predominantly sand, where there was no alternate route of travel, where remedial action was under way, without any notice or warning to that effect. Thus, the question which was presented to the jury in this case was multifaceted and therefore dissimilar to the trial court’s treatment in Proctor of the legal effect of a single protruding brick on a city sidewalk. Given the fact that repair work was under way, which required visitors to walk from the brick walkway to a sand path, with minor elevation change, a reasonable person could find that these conditions, in toto, were sufficient to warrant some warning to the visitors. Absent the same, a reasonable person could find that the District failed to exercise reasonable care and thereby caused appellee’s injuries.
Moreover, unlike the Proctor case where the height of the protruding brick was not a contested factual issue for the jury to decide, here reasonable persons could differ as to the condition of the walkway when ap-pellee fell. To rebut the appellee’s testimony that the level of sand was below the level of brick, the District offered the testimony of Lorton employees who stated that the sand compound was even with the brick walkway before, during, and after visiting hours on the day appellee fell. Testimony was also presented, however, indicating that approximately 200 people had stepped across the sand-filled area, thereby creating some indication that a depression had formed. Thus, the jury was entitled to consider and resolve this contested issue of fact — i.e., the condition of the walkway when appellee fell.
As reasonable people could differ on the record before us, it was not error for the trial court to submit the case to the jury and deny appellant’s motion for judgment non obstante veredicto.
Affirmed.
. This case was initially heard by a division of the court. The opinion which was rendered, District of Columbia v. Cooper, (No. 80-206, June 2, 1981), was later vacated and the matter was presented to the full court.
The view has been expressed, in dissent, that the questions presented by this case are not of sufficient importance to warrant the en banc attention of this court. From the vantage point of trial judges and attorneys, however, there is considerable importance in providing a guide, as best we can, to a problem which is recurring, significant to the outcome of many cases, and likely to be the basis for advice which is given to potential litigants. That we appear closely divided on such a fundamental concept does not lessen the need to confront it.
. Appellant also asserts that assuming arguen-do that appellee’s evidence was sufficient to establish the existence of a dangerous condition on the Lorton walkway, appellee failed to establish that the District had actual or constructive knowledge of the defect sufficiently in advance of appellee’s fall to give the District a reasonable time within which to take proper corrective action. We do not reach the District’s notice argument since it is conceded the District had actual knowledge of the defect and took what it perceived as reasonable corrective action.
. Indeed, “[i]t must be kept in mind that it is the unusual case in which only one conclusion reasonably could be drawn from the evidence, and in which negligence, contributory negligence, and proximate cause will not be questions of fact for the jury." Rich v. District of Columbia, D.C.App., 410 A.2d 528, 532 (1979).
. Although appellee Cooper testified on cross-examination that the difference in surfaces was one-eighth of an inch, this estimated measurement — unlike the description given by the plaintiff in Proctor — did not become the focal point of the trial. Indeed the District refused to accept appellee’s characterization regarding the condition of the walkway. Rather, the District continually asserted that there was no difference in elevation whatsoever.