This is an appeal by the plaintiff below from an adverse verdict and judgment in favor of three corporate defendants in a personal injury action. The plaintiff-appellant will be referred to herein as “plaintiff” and the defendants as “defendants Tobin and Clarkson” and “defendant Safe-T-Flare”. The points on appeal involve the propriety of a converse instruction of defendants Tobin and Clarkson and asserted error in the rulings of the trial court as to the admissibility of certain evidence proffered by the plaintiff. The trial court overruled plaintiff’s after trial motions, judgment was entered against her and this appeal followed.
All defendants argue that any alleged error charged here either as to instructions or admission or exclusion of evidence are immaterial and non-prejudicial since the plaintiff failed to make a submissible case of negligence against any of the defendants.
At the outset, therefore, it is necessary to view the basic and well-established rules which prescribe the scope of this court’s review in a case of this kind and *539where such a contention is raised by the respondents, because, of course, if under such rules and principles the plaintiff made no submissible case the trial court erred in not directing a verdict for defendants and the matter ends there. In such circumstance, in determining whether a submissi-ble ease was made, the evidence must be considered in the light most favorable to the plaintiff and she must be given the benefit of all favorable inference which may be reasonably drawn from the evidence and all evidence will be accepted as true which is not entirely unreasonable or contrary to physical facts or natural laws. Epple v. Western Auto Supply Co., 548 S.W.2d 535, 537, 538[1] (Mo.banc 1977), supplemented 557 S.W.2d 253; Green v. Crunden Martin Mfg. Co., 575 S.W.2d 930, 932[1] (Mo.App.1978).
The record on this appeal is voluminous, consisting of 1050 pages and 86 exhibits. However, for the purpose of ruling this contention of the defendants upon the application of the principles as stated in Epple and Green, supra the facts pertinent to their argument and to the points raised by appellant on this appeal may be thus summarized:
Prior to April 21, 1974, the J. A, Tobin Construction Company and Clarkson Construction Company, separate corporations, entered into a joint venture contract with the Missouri Highway Department for the construction, grading and widening of the roadway of Interstate Highway No. 29 which contract included a stretch of 1-29 near Route AA in Platte County, Missouri. Under the terms of this contract the joint venturers became responsible for handling traffic, barriers, barricades, signs, flagmen, and warnings necessary to protect members of the traveling public using the highway during the construction project.
Under a separate agreement defendants Tobin-Clarkson entered into an agreement with defendant Safe-T-Flare to supply the markers, signs, etc. necessary to accomplish this result on the project, including four-legged sawhorse type warning signs carrying electric blinkers commonly known as ‘No. 2 signs”. These signs were used, among other purposes, to place along the edge between the traveled portion of a construction project and that portion not usable because of a drop-off or other danger, to warn oncoming traffic of that dangerous condition. There was substantial evidence that the defendants Clarkson-Tobin, subject to inspection by a highway department project observer, determined the placement and number of such signs in use of the project. While there was some conflict (or at least confusion), there was evidence that defendant Safe-T-Flare’s obligation with reference to the No. 2 signs was to periodically inspect the signs and keep them in repair or replace damaged signs. This defendant periodically inspected the signs on the project site and, by reasonable inference, removed or caused the project contractors to remove conditions of obvious danger to the traveling public referable to the signs.
The record discloses that in certain weather conditions or when a large motor vehicle such as a bus or a freight hauling truck passed such a No. 2 sign the rush of air sometimes blew them over. Under such conditions they were sometimes anchored by sandbags tied to the horizontal crosspiece to add weight.
A Mr. Box testified in behalf of plaintiff. He was the principal partner in the firm of Paul C. Box and Associates, traffic engineers and consultants in the field of design, planning, operation of streets and highways in terms of efficiency of traffic flow, safety of the public, improvement and accident reconstruction.
He and his firm had done such traffic engineering work for many cities, counties and states (including many in Missouri) and for the federal government. His academic and professional qualifications as an expert were impressive and were not and are not challenged.
He was familiar with the No. 2 type sawhorse warning signs. Their purpose was to warn traffic past and around obstructions or other dangers existing from highway construction. Their design con*540templates that any impacting force would drive a No. 2 sign forward and downward and underneath the impacting vehicle to prevent the sign from being thrown sideways or into the vehicle impacting so that it would not become a dangerous projectile. Box stated that if such signs needed added weight due to weather or traffic conditions this would be done by tying sandbags to the sign. The placing of loose rocks on top of a No. 2 sign is not good practice nor is it safe since an impacting vehicle will underride the rock and it will likely become a projectile into the windshield of the vehicle.
Box testified that he was familiar with the site of this accident and that, in his opinion, No. 2 signs should be inspected there once a day since the location was heavily traveled. The accident happened on a Sunday and the evidence showed that Clarkson’s job superintendent and its safety director were last on the job site on Saturday and Safe-T-Flare’s employee was last on the site on Friday.
On Sunday, April 21, 1974, at approximately 12:15 p. m. one Stephen Ballard was driving his 1965 Rambler automobile in a generally northerly direction on Interstate No. 29 along the construction site as described .2 of a mile north of AA overpass. Riding as a passenger in his car in the right front passenger seat was the plaintiff, Bonnie Swindell, at the time of the trial 23 years of age. She and Ballard had been to church and were headed to the farm of Ballard’s parents to go horseback riding. Ballard testified that he was familiar with this road and the construction work in progress since he drove it at least twice a day going to and from his employment.
He testified that as he was proceeding on the traveled portion of 1-29 at 40 miles per hour (the posted speed) he lost steering control of his car; his car abruptly swerved to the right; his right wheels went off the traveled highway into the drop-off where the widening construction was in progress; his car struck two or three of the No. 2 warning signs; swerved back onto the traveled highway; and, came to rest several hundred feet north. He stated that the steering ball joint on his car was broken in two after the accident.
Ballard stated that during his daily use of 1-29 during this construction he had frequently observed rocks placed on top of the No. 2 warning signs along the traveled portion of the highway and that on the occasion in question just before he hit the first barricade he observed a large rock on top of that sign. He stated that the impact propelled the rock through the right front windshield of his car and that it was later found on the rear floorboard of his car. Photographic exhibits of the car disclosed a large hole in the windshield of the Ballard car and photos of the rock found inside the car were offered and received in evidence. There was testimony that it weighed approximately 40-50 pounds.
Ballard testified that after the impact the plaintiff slumped over onto his lap, was unconscious, was bleeding profusely from the head and he and the plaintiff were thereafter taken by ambulance to the hospital. Ballard noticed the plaintiff’s face appeared to be “smashed”.
Plaintiff did receive substantial injuries including loss of vision in her left eye; brain damage, multiple facial fractures to her nose, left eye socket, teeth and upper and lower jaws and a subdural injury to her brain. There was no substantial dispute as to the nature and extent of her trauma and resulting injuries, only the residual or permanent results were in any way contested. She testified she had no recollection of any events on the Sunday in question having first regained any consciousness in the hospital several days later. Apparently she suffered from retrograde amnesia, and was unable to add any testimony nor did she have any recollection of the facts of the accident.
Michael Murphy who lived in the area and used 1-29 daily to go to and from his home to his employment at the Federal Reserve Bank in Kansas City testified that he had upon a number of occasions seen rocks which had been placed on top of the sawhorse type warning signs along the construction area. The evidence offered by the *541defendants was to the effect that rocks were never placed on top the No. 2 signs.
As a preliminary consideration the argument contained in all defendants’ briefs as Point III must be addressed. The defendants assert that the alleged error in converse Instruction No. 3 submitted by defendants Tobin-Clarkson, or in the trial court’s rulings on the admission of evidence was immaterial and harmless because the plaintiff failed to make a submissible case. The argument is, in substance, that plaintiff failed in this regard because she did not sustain her burden of proving a duty, breach thereof and resultant proximate causation of her injuries. It is urged that, when viewed in the light of foreseeability and probability, the plaintiff’s case fails and a directed verdict for the defendants should have been granted.
No feasible argument as to the existence of a duty, both under the terms of the Tobin-Clarkson contract with the Missouri Highway Department and the principle that highway contractors have a continuing and non-delegable duty to exercise reasonable care for the safety of the public using the highway, is tenable. Best v. Fred Weber Construction Co., 525 S.W.2d 102, 108 (Mo.App.1975). This obligation logically carries with it a concomitant duty to use ordinary care to avoid creating a dangerous condition near a traveled thoroughfare. M.A.I. 22.02. If the defendants placed a rock on top of the No. 2 sawhorse warning sign and to do so constituted a hazardous and dangerous condition, as testified by expert witness Paul Box, the plaintiff’s evidence established both the duty and a breach thereof.
The test of what was the proximate cause of the injury is whether, after the occurrence, the injury appears to be the reasonable and probable consequence of the act or omission of the defendant, not whether a reasonable person could have foreseen the particular injury. Green v. Kahn, 391 S.W.2d 269, 277[10] (Mo.1965); Foley v. Hudson, 432 S.W.2d 205, 207[2] (Mo.1968). An efficient, intervening cause has been consistently recognized as a new and independent force which so interrupts the chain of events as to become the responsible, direct, proximate and immediate cause of injury, and may not consist of an act of concurring or contributory negligence. Seely v. Hutchison, 315 S.W.2d 821, 826[6] (Mo.1958). Proximate cause and intervening, efficient cause issues are for the jury when contradictory factual evidence is presented as to negligence and causation, and the facts presented are of such a nature and are so connected and related to each other, that the conclusion that the negligence charged was the proximate cause of the injury may be fairly inferred. Morris v. Isreal Brothers, Inc., 510 S.W.2d 437, 442-443[4, 5] (Mo.1974).
The evidence, viewed favorably to the plaintiff, reveals and a jury could find that a large rock was on top of the sign struck by Ballard’s car; the impact hurled the rock through the windshield and struck the plaintiff in the face and head severely injuring her; that by contract and law the defendants Tobin-Clarkson were responsible to furnish barriers, signs and barricades to protect the safety and the property of persons using the highway; that defendant Safe-T-Flare by contract with Tobin-Clark-son furnished and maintained this equipment; that Ballard, due to mechanical failure of his car left the traveled portion of the highway, the right side of his car passed down the 12-inch drop-off onto the excavation for the construction and struck the sign which had been weighted with the rock.
The evidence further justified findings that these rocks were placed on top of the signs at this site prior to the accident (a fact in dispute) .and this practice was unsafe as it defeated a purpose of the sign design, namely, to collapse forward at ground level to minimize danger and injury to impacting vehicles and persons in case of collision and that, in such event, a loose rock placed on top of the sign by the force of basic physics would likely be projected into the impacting vehicle; that the proper, safer method of weighting these warning signs was to use sandbags suspended from the horizontal crossbars and secured by ropes or wire; *542that the site of the construction was one of heavy traffic volume requiring daily inspection; and that Clarkson’s safety director and Safe-T-Flare’s employees were last on the site two days before the accident and Clarkson’s superintendent the day before.
The court is not unmindful of the fact that much of the above-summarized evidence was disputed and contrary evidence was offered, such as the evidence of the defendants that rocks were never placed on top of the No. 2 signs to weight them. However, the conclusion is reached that the evidence presented a submissible case under proper instructions and the court did not err in denying the defendants’ motions for directed verdicts.
The plaintiff-appellant vigorously attacks the propriety of the defendants’ Tobin-Clarkson’s converse Instruction No. 3 and charges the trial court with error in giving that instruction under the facts of this case. The argument is based primarily upon the contentions that said converse instruction violated the requirement that the converse be in substantially the same language as the plaintiff’s verdict directing Instruction No. 2 and further that this converse No. 3 improperly and erroneously advised the jury and required them to find that both Tobin and Clarkson failed to use ordinary care as a condition precedent to recovery by the plaintiff against either defendant.
Before any discussion of this point or analysis of the instructions it is well to keep in mind that it was undisputed that on the construction work on 1-29 involved in this case Tobin and Clarkson were acting as joint venturers. As such, their liability as to third parties for negligence was joint and several. See Atkinson v. Herington Cattle Company, 436 P.2d 816, 200 Kan. 298; Cherokee Village v. Henderson, 538 S.W.2d 169 (Tex.Civil App.). Their liability as to third persons is governed by the principles of partnership and agency law. See: 48 C.J.S., Joint Adventure, Sec. 14(a), pp. 866, et seq.
The plaintiff’s verdict director as against defendants Tobin and Clarkson was as follows:
INSTRUCTION NO. TWO
Your verdict must be for Plaintiff and against Defendant Clarkson Construction Company and Defendant J. A. Tobin Construction Company, if you believe:
First, either Defendant allowed a No. 2 barricade to be weighted with a rock on top adjacent to the traveled portion of the highway and as a result, the No. 2 barricade was not reasonably safe to the public, and
Second, either Defendant failed to use ordinary care to remove such unsafe conditions, and
Third, such failure directly caused or directly contributed to cause damage to Plaintiff.
(Emphasis added)
This verdict director properly declares the law in Missouri that joint ventur-ers are jointly liable for personal injuries sustained by third parties, even though the actual negligent act or acts of commission or omission (and therefore the actionable negligence) is that of some but not all of the members of the joint venture. Pigg v. Bridges, 352 S.W.2d 28, 33[7] (Mo. banc 1961). It should here be noted that Clark-son had the work force, superintendent and safety director on the project and although Tobin was a joint venturer on the job its people or officials were rarely even on the job site and their regular employees were not doing the work.
The Tobin-Clarkson converse instruction reads as follows:
INSTRUCTION NO. THREE
Your verdict must be for Defendants Tobin and Clarkson unless you believe Defendants Tobin and Clarkson failed to use ordinary care as submitted in Instruction No. 2 and that Plaintiff sustained damages as a direct result thereof. (Emphasis added.)
This converse instruction is necessarily confusing when considered in the light of the proper verdict director (No. 2) above *543quoted. Further, because of the relationship of Tobin-Clarkson as joint venturers it improperly and erroneously declares the law under this record. This is true and obvious since it was not necessary for the jury to find that both Tobin and Clarkson “failed to use ordinary care” in order to find both liable to the plaintiff. The negligence of either rendered both liable by reason of their legal relationship. Thus, Instruction No. 3 constituted a violent misdirection to the jury and its effect was misleading and confusing and was necessarily prejudicial to the plaintiff and it was reversible error to give that instruction.
The parties’ briefs do not eite nor has independent research disclosed any Missouri authority directly in point. Close and persuasive analogies may be drawn, however, with those cases where co-parties’ rights stem from different theories of liability or elements of damage.
The cases of Long v. REA Express Co., 573 S.W.2d 62, 67[7, 8] (Mo.App.1978), and Mayberry v. Clarkson Construction Co., 482 S.W.2d 721, 724-26[5, 6] (Mo.1972), held converse instructions that were confusing, misleading, and erroneous to be reversible error. In the Mayberry case, plaintiff’s husband and wife each sued both for personal injuries and for loss of consortium with the other spouse. The converse required a verdict for defendant unless the jury believed each proposition submitted in three separate verdict directors. Because this converse placed the three verdict directors in one category when in fact each represented a separate claim, this told the jury that either the plaintiff were to recover on all three, or on none. The Long case similarly involved plaintiffs husband and wife bringing suit for personal injuries and loss of consortium, except that two defendants were named. In their converse, defendants altered the words “plaintiff” and “defendant” to plural form. This, in effect, required a finding that both plaintiffs sustained damages as a condition precedent to recovery against defendants by either (l.c. 67), which was held to be misdirection and reversible error. The converse should allow the jury to find for plaintiff on each theory submitted, and should not deprive the plaintiff of any possible theory of recovery. See Royal Indemnity Co. v. Schneider, 485 S.W.2d 452, 457-58[2] (Mo.App.1972).
Davis v. St. Louis Southwestern Railroad Co., 444 S.W.2d 485, 489[4] (Mo.1969) is another case wherein remand for new trial was had because a converse erroneously limited plaintiff’s theory of recovery. In Davis, a personal injury action was brought under FELA against an employer based on the negligence of either the defendant-employer in failing to provide reasonably safe work methods, or another employee’s negligence in dropping a brake beam on a hammer handle. The converse submitted by defendant required a verdict for defendant if the jury did not believe defendant was negligent. Because this improperly deprived the plaintiff’s theory of recovery against the employer for the negligence of plaintiff’s co-employee, the converse was held to be error.
Under the principle of these foregoing cases, it was reversible error for Instruction No. 3 to require that both defendants Tobin and Clarkson failed to use ordinary care in order to return a verdict for plaintiff, because a finding that either defendant was negligent would support a verdict against both.
It is concluded that the giving of Instruction No. 3 constituted reversible error under this record.
As to the defendant Safe-T-Flare a different situation is presented. The plaintiff submitted a separate verdict director (No. 4) as to Safe-T-Flare and it offered a separate converse instruction (No. 5). It was entirely proper that this be done in this case for a number of reasons. Safe-T-Flare’s position in this case is that of working under contract, not with the Missouri Highway Department, but with defendants Tobin-Clarkson. Under this agreement it furnished certain barricades, markers and signs as requested by Tobin-Clarkson on a rental basis. The ownership of the signs remained that of Safe-T-Flare. It had no direct obligation either to the state or the *544public, although it did undertake to maintain them and replace any that were destroyed or damaged and to undertake periodic inspections of its equipment. The barricades, markers and signs were furnished and placed at the times and locations as directed by Tobin-Clarkson. The No. 2 sawhorse sign here involved was one of such pieces of equipment. There is no claim that this sign was of improper design or in any way defectively constructed. The charge is and the plaintiff’s evidence showed that it was improperly weighted by the rock. The jury under proper instructions as to the liability of Safe-T-Flare found for it and the evidence and instructions justified such conclusion.
Because of the interrelationship of the parties, including the state and traveling public, Safe-T-Flare’s liability to plaintiff could only be that of a joint tortfeasor. No vicarious liability existed as to it. It would be liable, if at all, jointly and severally with its codefendants. It has long been the law in Missouri that a new trial may be granted as to some defendants, where the liability among them is joint and several, if such can be done without confusing the issues. Nix v. Gulf, Mobile and Ohio R. Co., 362 Mo. 187, 240 S.W.2d 709, 712[1] (1951); Mount Arbor Nurseries v. New York C. & St. L. R. Co., 217 Mo.App. 31, 273 S.W. 410, 415[13] (1925); Costello v. Kansas City, 209 Mo.App. 155, 232 S.W. 165, 167[1] (1921). The error in this case was in the converse Instruction No. 3 as to defendants Tobin-Clarkson not as to the instructions relating to defendant Safe-T-Flare.
Converse Instruction No. 4 given for Safe-T-Flare presented no interwoven, overlapping, dependent or confusing issues as to all defendants.
The appellant raises as her Point II on this appeal the contention that the trial court erred in excluding certain proffered evidence pertaining to the claimed custom and practice of the defendants of weighting No. 2 warning signs with rocks placed on the cross members on this and other construction sites.
This proffered evidence which was excluded by the trial court consisted of the testimony of John Ramsey and Robert Bruce and certain photographs of highway construction sites. Both would have testified to the effect that they had witnessed instances of rocks placed atop barricades. Bruce had been a safety director for Tobin from 1969 until April, 1971. Ramsey had been safety director for Tobin from November, 1972 until March, 1975. Neither witness was acquainted with the job site in question. Their proffered testimony was to the effect that rocks had been placed on top of barricades before, during, and after the construction, but at different locations. Plaintiff offered this as collateral evidence of habit and custom.
In order to prove the absence or presence of due care, custom or practice evidence is admissible if the proof shows the witness possessed knowledge of the existence of the custom, the custom was a well-known and widespread trade custom and not confined to the practice of certain individuals only, and the custom is a definite, uniform, and known practice under certain definite and uniform circumstances. Wright v. Chicago, Burlington & Quincy Railroad Co., 392 S.W.2d 401, 405[3, 4] (Mo. 1965); Davis v. Gatewood, 299 S.W.2d 504, 509-511[4-7] (Mo.1957). Isolated instances or several instances do not establish a custom. See Smith v. Alaskan Fur Co., 325 S.W.2d 740, 743[1] (Mo.1959) where plaintiff testified she had seen a mat at defendants’ entranceway when it was raining on previous occasions. This was held insufficient to show a custom.
The trial court cannot be said to have erred in excluding this testimony. The inadequacies of plaintiff’s proffered evidence are numerous. The record nowhere discloses that this was a known and widespread custom. There was no evidence as to the similarities or dissimilarities between the present job site and the other proffered sites with respect to wind conditions and barricade placement. The testimony of Bruce and Ramsey was their observation at job sites operated by Tobin, when the site in *545question was that operated by Clarkson, of which site they had no personal knowledge.
Some of the photographs offered by the plaintiff were admitted into evidence and others were excluded. Those excluded in some particulars labored under the same lack of qualifying evidence and some confusion in the record as to time, place and identity of the contractor involved.
The trial court obviously concluded that the proffered evidence fell short of admissible proof of custom and practice. It was within the trial court’s sound discretion to exclude such evidence offered solely for the purpose of establishing custom and practice.
The judgment below is affirmed as to defendant Safe-T-Flare Rental Service, Inc. and reversed and remanded as to defendants J. A. Tobin Construction Company and Clarkson Construction Company for a new trial as to those defendants.
SHANGLER and PRITCHARD, JJ., concur in separate opinions filed.
MANFORD, J., concurs in majority opinion of SWOFFORD, Senior Judge.
CLARK, J., dissents in separate opinion filed.
SOMERVILLE, C. J., and TURNAGE, J., dissent and concur in dissenting opinion of CLARK, J.