concurring.
The law imposes upon a contractor for highway improvements a nondelegable duty of care for the safety of persons who lawfully use the way. Best v. Fred Weber Construction Co., 525 S.W.2d 102, 108[13, 14] (Mo.App.1975). That duty for safe passage extends to traffic on the contiguous shoulder area. Penn v. Columbia Asphalt Company, 513 S.W.2d 679, 687[11, 12] (Mo.App.1974). A contractor who creates a condition on the highway or on the shoulder dangerous to persons on the thoroughfare, therefore, is negligent. [That the excavation was to extend the pavement rather than to install another shoulder does not alter the construction as highway work and the attendant duty of care, nor render the risk of injury to a lawful motorist any the less foreseeable.] That is not to say that to be liable a contractor must foresee the precise danger or the exact consequence. Rather [as the principal opinion instructs], actionable negligence — the foreseeability that injury will result from conduct — is tested prospectively: what a reasonable person should anticipate. Gruetzemacher v. Billings, 348 S.W.2d 952, 957[3] (Mo.1961). The consequence is tested retrospectively: whether the injury was the normal result of the act or the omission. Reckert v. Roco Petroleum Corporation, 411 S.W.2d 199, 205[7] (Mo.1966); Restatement (Second) of Torts § 435 (1966). Thus, our law rests tort liability on the principle that, where conduct creates a foreseeable risk of harm to another, it does not avail to say that the very injury incurred or the full course of consequences could not be foreseen. Boyd v. Terminal Railroad Association of St. Louis, 289 S.W.2d 33, 37[2, 3] (Mo.1956); Harper & James, The Law of Torts § 20.5, p. 1147 (1956).
I understand the principal opinion to say that a highway contractor who excavates an open trench contiguous to the travel lanes of the roadway and undertakes to warn of that condition by a sign on the excavation weighted atop by a fifty-pound rock will anticipate, in the exercise of the duty of care the law expects, that a vehicle operated upon the roadway at a lawful speed and in a lawful manner — but which becomes unmanageable by a sudden failure of the steering mechanism — may veer from the paved roadway onto the shoulder excavation and impact with the sign so as to *548traject the rock into the vehicle and injure the occupant. I agree with the principal opinion that the injury is within the compass of the original unreasonable risk of harm created by the contractor and so is actionable.
I concur.