(concurring in part and dissenting in part).
[¶ 48.] I concur except on Issues 3 and 5. I dissent on those issues because Bland was denied a fair trial as a result of the trial court’s refusal to allow impeachment of County’s employee, and its refusal to allow Bland’s expert to testify as to reasonable standard of care. We should reverse and remand for new trial.
[¶ 49.] 3. THE TRIAL COURT ABUSED ITS DISCRETION BY REFUSING TO ALLOW IMPEACHMENT OF A WITNESS IN ACCORDANCE WITH THE EXCEPTION TO THE SUBSEQUENT REMEDIAL MEASURE RULE
[¶ 50.] Shortly after the accident, law enforcement called the highway department and requested sanding of the stretch of ice on Loomis road. Bland was not allowed to introduce evidence of the post-accident sanding, or the actions of County’s employee in warning traffic at the scene, because it was incorrectly excluded under the “subsequent remedial measure” rule:
When, after an event, measures are taken which, if taken previously, would have made the event less likely to occur, evidence of the subsequent measures is not admissible to prove negligence or culpable conduct in connection with the event. This section does not require the exclusion of evidence of subsequent measures when offered for another purpose, such as proving ownership, control, or feasibility of precautionary measures, if controverted, or impeachment.
SDCL 19-12-9 (FedREvid 407) (emphasis added).
[¶ 51.] Bland argues she should have been able to introduce the evidence under the impeachment exception to the rule. While County admits to a policy where this area was never sanded, even when its employees knew the ice was present, Bland attempted to show that the condition of the ice that day was different and more dangerous than normal. Assistant Department Superintendent King (King) testified by deposition that he stayed at the accident scene for approximate*465ly an hour with his hazard lights flashing, to warn “other oncoming traffic that something was wrong,” and that he did not leave until a sand truck arrived. At trial, he testified that “there was nothing wrong” and that the road was not dangerous. The trial court ruled that King could be impeached, but only regarding his trial testimony that nothing was wrong. The trial court refused to allow the deposition testimony showing King waited an hour to warn other traffic, that his hazard lights were flashing, or that the area was sanded.
[¶ 52.] The trial court’s evidentiary rulings are reviewed under the abuse of discretion standard. State ex rel. Dep’t of Transp. v. Spiry, 1996 SD 14, ¶ 11, 543 N.W.2d 260, 263 (citations omitted). Under this standard, “not only must error be demonstrated, but it must also be shown to be prejudicial error.” Id. (quoting Shaffer v. Honeywell, Inc., 249 N.W.2d 251, 258 (S.D.1976)). Prejudicial error is “that which in all probability must have produced some effect upon the final result and affected rights of the party assigning it.” Id. (quoting K & E Land & Cattle, Inc. v. Mayer, 330 N.W.2d 529, 533 (S.D.1983)).
[¶ 53.] There is no basis to exclude evidence of subsequent remedial measures when offered to impeach testimony, as the rule expressly permits impeachment. Traylor v. Husqvarna Motor, 988 F.2d 729, 734 (7th Cir.1993).
It is the general rule ... that evidence of precautions taken and repairs made after the happening of the accident is not admissible to show a negligent condition at the time of the accident [but] such evidence may be admitted to impeach the testimony of a witness who has testified that the condition prior to the accident was not a dangerous one.
Love v. Wolf, 249 Cal.App.2d 822, 58 Cal.Rptr. 42, 48 (1967); cf. Kenny v. Southeastern Pennsylvania Transp. Auth., 581 F.2d 351, 356 (3rd Cir.1978), cert. denied, 439 U.S. 1073, 99 S.Ct. 845, 59 L.Ed.2d 39 (1979) (“[W]hen the defendant opens up the issue by claiming that all reasonable care was being exercised at the time, then the plaintiff may attack that contention by showing later repairs which are inconsistent with it”) (citing 2 J. Weinstein & N. Berger, Weinstein’s Evidence ¶¶ 407[03], [04] (1977)).
[¶ 54.] The majority claims Bland was not prejudiced. The prejudice resulted from the fact that the jury was denied the evidence it needed to properly perform its duty. The majority attempts to set forth, supra at ¶ 22, testimony which supposedly refutes any claim made by King downplaying the condition of the road. That testimony simply reiterates the icy conditions, which are essentially undisputed. What Bland was not allowed to impeach was King’s assertion the road was not dangerous, when in fact he stayed at the accident scene for an hour to warn traffic something was wrong. This went beyond merely ordering sanding, and refutes King’s characterization of the road as merely icy. Evidence tending to establish negligence should not be kept from the jury. The majority wants to sterilize the court proceedings to permit only evidence favorable to the county. That is not our job on appeal. As noted, evidentiary rulings are reviewed under an abuse of discretion standard. However, whether to allow impeachment also involves construction of SDCL 19-12-9; mixed questions of fact and law requiring the application of a legal standard are reviewed de novo. Abild v. Gateway 2000, Inc., 1996 SD 50, ¶ 6, 547 N.W.2d 556, 558-59 (citation omitted).
[¶ 55.] I agree with Bland that it was an abuse of discretion for the trial court to disallow this impeachment of King. Bland was prejudiced by the ruling because the jury was allowed to hear King’s uneontro-verted testimony that downplayed the condition of the road that day. We should reverse on this issue.
[¶56 ] 5. BLAND’S EXPERT SHOULD HAVE BEEN ALLOWED TO TESTIFY TO STANDARDS OF ROAD MAINTENANCE BY COUNTIES AND OTHER GOVERNMENTAL ENTITIES
[¶57.] Bland argues that the trial court erred when it excluded her expert’s testimony regarding a reasonable standard of care in the maintenance of roads. As noted above, evidentiary rulings will not be dis*466turbed in the absence of the trial court’s abuse of discretion. The trial court ruled, before trial, that experts would not be allowed to testify to what a county “should do” or to what is “reasonable” for a county to do in the way of road maintenance. The court’s ruling limited expert testimony to what “could” be done.
[¶ 58.] County argues that it would not have made a difference if the experts testified on a reasonable standard of care because the jury would simply be presented with two different, subjective opinions. However, County’s argument relates to credibility, not to admissibility. “It is a function of the jury to determine the credibility of the witnesses and to accept one witness’ version of the facts and reject another’s.” State v. Larson, 512 N.W.2d 732, 737 (S.D.1994) (citations omitted). Without the excluded testimony, the only standard of care heard by the jury was County’s policy or practice of not sanding visible stretches of ice.
[¶ 59.] The statute governing admissibility of expert testimony provides:
If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise.
SDCL 19-15-2 (FedREvid 702). The trial court has broad discretion concerning the admission of expert testimony and its decision on such matters will not be reversed absent a showing of an abuse of discretion. State v. Hill, 463 N.W.2d 674, 676 (S.D.1990).
[T]he determining factor in admitting expert testimony is if it would assist the jury in understanding matters that normally would not lie within a layman’s breadth of knowledge. When opinions are excluded, it is because they are unhelpful and therefore superfluous and a waste of time.
Schaffer v. Edward D. Jones & Co., 1996 SD 94, ¶ 8, 552 N.W.2d 801, 805 (finding no abuse of discretion in the admission of expert’s testimony when it was sufficiently helpful to the jury under the standard set forth in SDCL 19-15-2 in understanding the issues involved in that case) (citations omitted).
[If 60.] Apparently the trial court equated expert testimony concerning a reasonable standard of care with expert testimony concluding County was negligent. They are not the same, and the trial court’s reliance on Zens v. Harrison, 538 N.W.2d 794 (S.D.1995), was misplaced. In that case, we affirmed the trial court’s exclusion of the portion of an expert’s testimony where he opined the defendant was negligent in his instruction and supervision of the workplace. Id. at 795-96. A review of Bland’s offer of proof, supra ¶ 29, demonstrates that “whether County was negligent” was not the testimony which Bland sought to elicit from her expert. Furthermore, we have recently stated that “an expert’s testimony is not inadmissible merely because it may involve an ultimate issue for the jury.” State v. Barber, 1996 SD 96, ¶ 37, 552 N.W.2d 817, 823 (relying upon SDCL 19-15-4 (Fed.R.Evid.704), which provides: “Testimony in the form of an opinion or inference otherwise admissible is not objectionable because it embraces an ultimate issue to be decided by the trier of fact.”). Obviously, it is an abuse of discretion to disallow expert testimony solely on the basis that it embraces an ultimate issue. Id.
[¶ 61.] We stated in Bland v. Davison County, 507 N.W.2d 80, 82 (S.D.1993) (Bland I), that “evidence of an accumulation of snow or ice over a long period of time on a highway may present a hazard to motorists and creates a jury question as to the ordinary and reasonable maintenance provided by County.” (Emphasis added). Obviously, road maintenance is not within a “layman’s breadth of knowledge,” Schaffer, supra, and therefore, expert testimony regarding the subject would be sufficiently helpful to the jury and should be admitted. Without the support of expert testimony to establish a standard of care by which County’s conduct could be judged, the jury was denied evidence necessary to properly decide the issue of negligence. In effect, the jury was denied the tools to do its job.
[¶ 62.] The majority argues incorrectly that our decision in Zens points to exclusion of the expert testimony; a simple review of that *467case instructs to the contrary. In Zens, the plaintiff sought the expert’s opinion on whether the defendant was “negligent”; here, Bland’s expert would have testified to an ordinary standard of care concerning highway maintenance. The expert in Zens was allowed to testify whether the workplace was “reasonably safe” — what is the difference between that testimony and the testimony excluded here? The majority completely ignores Barber, 1996 SD 96 at ¶¶ 37-38, 552 N.W.2d at 823 and SDCL 19-15-4, which state the settled law, i.e., expert testimony is not inadmissible merely because it “involves” or “embraces” an ultimate issue for the jury. The majority also states the average person can reach their own conclusion regarding whether a reasonable standard of care requires that an icy road be sanded based upon their own experience of driving, or owning a driveway or sidewalk. The average person probably does have an opinion on any given subject; as noted in Justice Konenkamp’s special writing, this is not a reason to exclude expert testimony concerning a reasonable standard of care. See infra ¶ 64 (quoting John W. Larson, South Dakota Evidence § 702.1, at 475 (1991)). The deck was stacked on this issue in favor of County, and Bland deserves a new trial.13 We should reverse on this issue.
. The majority incorrectly characterizes Bland's argument on both Issues 3 and 5. See supra note 8 & ¶ 36. She did not argue that a successful result on appeal on either issue was contingent upon like success on Issues 1 and 2. She simply argued that juror bias and misconduct, factors she obviously believes were present, were compounded by the trial court's refusal to allow impeachment and refusal to allow testimony concerning the correct standard of care. Obviously, one erroneous evidentiary ruling can warrant reversal. See, e.g., State v. Moeller, 1996 SD 60, 548 N.W.2d 465.