Assured Clear Distance Ahead and Vision Zero

Too often, bicyclists are treated as scapegoats for the consequences of negligent motoring behaviors. This tactic was on clear display at the October 6 meeting of the HB232 Bicycle Safety Law Study Committee. A committee member who is antipathetic to bicyclists told a story of a motorist who was pulling a boat at high speed on a narrow rural road when he crested a hill and spotted a single bicyclist ahead traveling the same direction. The motorist reported that he could not slow in time, but instead swerved right and crashed into a ditch in order to avoid the bicyclist and oncoming traffic in the other lane. The motorist and the committee member blamed the damage to the driver’s property on the bicyclist.

The State Traffic Engineer expressed similar sentiment, saying that bicyclists should stay at the rightmost edge of such rural roads in order to allow high speed motorists enough space to pass them. He said that motorists have an expectation that other traffic will be moving at the speed limit, and that by traveling slower, bicyclists violate this expectation and create a danger. This was the basis of his opposition to allowing bicyclists to ride two abreast on rural roads with high posted speed limits, despite no evidence of rear-ending collisions actually happening to cyclists riding two abreast on North Carolina’s rural roads.

BikeWalk NC’s representative on the committee debated both committee members by describing safe vehicle operating practices, the visibility benefits of riding two abreast, and the practice of lane control to deter unsafe same lane passing. The State Traffic Engineer appeared unconvinced. Following the meeting, the state official asked BikeWalk NC a hypothetical question: “Suppose it’s a higher speed rural road, and it’s raining, so visibility is poor, and a motorist rear-ends a slower moving bicyclist. Are we going to say that the motorist was negligent in such a case?”

Answer: Yes.

Both the boat-trailering and rainy-condition scenarios are perfect examples of violation of the basic speed law. All drivers, regardless of their vehicle type, have a responsibility to drive no faster than is safe for conditions, including any braking performance limitations of their vehicle or weather conditions that reduce visibility distances. The relevant NC statute subsections are these:

§ 20-141. Speed restrictions.
(a) No person shall drive a vehicle on a highway or in a public vehicular area at a speed greater than is reasonable and prudent under the conditions then existing.
…
(m) The fact that the speed of a vehicle is lower than the foregoing limits shall not relieve the operator of a vehicle from the duty to decrease speed as may be necessary to avoid colliding with any person, vehicle or other conveyance on or entering the highway, and to avoid injury to any person or property.

The North Carolina Driver’s Handbook provides guidance on this:

“The faster you are moving, the farther ahead you must be able to see to allow enough distance for stopping.” (p. 46)

“Never drive at a speed at which you cannot stop within the distance you can see on the road ahead” (p. 62)

This principle is also known as “assured clear distance ahead.”

“The Assured Clear Distance Ahead (ACDA) is the distance ahead of a vehicle or craft which can be seen to be clear of hazards by the driver, within which they should be able to bring the vehicle to a halt. It is one of the most fundamental principles governing ordinary care and the duty of care and is frequently used to determine if a driver is in proper control and is a nearly universally implicit consideration in vehicular accident liability.”

Drivers who overdrive their sight distance and collide with slow or stopped traffic on the road ahead are typically cited for “failure to reduce speed.” Note that removing bicyclists from rural roads can’t prevent such crashes; drivers traveling at speeds unsafe for conditions inevitably crash into cars stopped in traffic or waiting to turn left, school buses, garbage trucks, mail carriers, pedestrians, police officers… any one of a multitude of legitimate road users, not to mention hazards such as fallen trees or animals. North Carolina needs to focus on the root cause of such crashes – unsafe speeds – if the state’s Vision Zero policy is to be taken seriously. From the North Carolina Strategic Highway Safety Plan:

“North Carolina is a Vision Zero State—even one fatality is too many on our roadways. This Plan articulates the way forward to achieve Vision Zero. The Plan’s vision, mission, and goals guide the development and implementation of strategies and actions to achieve Vision Zero.”

The Strategic Highway Safety Plan describes speed as an emphasis area:

“The North Carolina General Statutes (§20 – 141) refer to speeding as driving at a “speed greater than is reasonable and prudent under the conditions then existing,” while the State crash report form (Form DMV-349) defines speeding as either exceeding “authorized speed limit” or exceeding “safe speed for conditions.” Not only do higher speeds leave less time for drivers to perceive and react to roadway conditions or situations, they also lead to more severe impacts when collisions do occur. Because excessive speed can exacerbate all other roadway safety issues in North Carolina, progress in addressing speeding has the potential to positively affect other areas, as well.

“It takes the involvement of many parties to create a culture that encourages and expects safe speeds. Such parties include law enforcement, roadway designers, driver educators, and drivers themselves.”

Developing a culture of safe speed will ultimately require our public officials to stop blaming innocent victims in crashes involving unsafe motoring behaviors, and instead place higher expectations on those who wish to exercise the privilege of motoring on our shared roads. BikeWalk NC hopes that our Department of Transportation officials will take these critical steps as they develop their recommendations for the HB232 Bicycle Safety Law Study.