West Side Highway, New York, 1951


For many historic roads, constructed to earlier standards and different needs, the provision of a safe driving environment for the modern traveler requires special considerations. The unique design and history of most historic roads makes the standard application of modern safety features and devices without a comprehensive safety study both unwise and potentially unsafe. All too often historic features (walls, bridges, trees) are removed or seriously altered due to a concern such features may pose a hazard or as the result of an accident. In many instances such changes are made based on the fact that the features are of a design or in a location that would not be considered appropriate by today’s design and safety standards. Yet seldom do such actions include a comprehensive analysis identifying the full complement of features and factors that may generate an unsafe situation.

A safety plan should look at the historic road holistically. Accident statistics should be compared to the geometrics (horizontal and vertical alignment, sight distance and superelevation) and existing safety features (barriers, walls, traffic signals, shoulders). Consider, for example, automobiles striking a historic bridge balustrade—is the historic barrier a safety concern, or did a road widening approaching the bridge increase the exposure to the balustrade? Only with a thorough understanding of the current safety functioning of the historic road can an assessment be made to determine if historic features enhance or harm the safety of the motoring public.

California Route 1, Marin CountyConsult your local, state or federal land highway engineering office to determine features of your historic road that may be problematic, even dangerous. Before you are too quick to write-off everything of the past however, look carefully at how your road functions today. It is possible some of those old details may be functioning as effective safety devices even though that was never their design intent. Cobblestone pavement, for example, may be an effective tool for traffic calming (speed reduction).

There may be attributes of a historic road that will require modification or alteration for modern safety, use or environmental needs or requirements. Reconciling modern needs with historic roads can be difficult, but is seldom impossible. In addition to an engineering analysis, a safety study should also address the safety implications of historic roadside features (street trees, access drives, lighting, rock outcrops or balustrades). Only after completing such an analysis can historic road advocates and the managing organization make a wise assessment of the potential impact such additions or alterations may have on the historic road.


Concerns for liability (the legal responsibility a managing agency holds for a particular road or transportation system) direct many of the decisions on the design and management of our national highway network. All road managing agencies or owners, through local, state or federal law are required to provide a safe driving environment or sufficiently warn a motorist of a potentially unsafe situation. Tort liability is a situation in which an injury or harm has occurred, due to a breech of a preexisting duty (providing a safe road), resulting in the potential exposure for damages to be awarded to the injured party or parties.

Every state and local jurisdiction addresses liability differently. In some states liability cases against the government are limited, in others departments, even individuals, may be held directly accountable for an accident resulting on a roadway. Additionally the interpretation of responsibility in a tort liability situation may be interpreted very differently by different courts.

When investigating the potential liability risk a historic road may pose it is helpful to review the safety history of the road. In additional to physical elements that may have resulted in an accident (structures, barriers, trees, walls) it is also important to investigate driver behavior (under the influence of drugs of alcohol, seizure, poor eyesight, aggressive driving) and environmental conditions (poor weather, ice, distractions due to a billboard, missing signs or improperly functioning traffic signals). Try to determine larger patterns such as repeated accidents at particular locations or particular times of day and determine if past efforts to improve safety at accident sites have succeeded in reducing the number of accidents or if such efforts have “shifted” accident locations.

To minimize the risks associated with liability and safety, accommodations and additions to historic roads should be well documented. Crash tests, alternate constructions or flexible designs should be provided as part of a written record citing the safety rationale for the selected design.

The following issues, features or concepts may be addressed in a safety and liability analysis:

engineering design
Most of the fundamental safety components of any road are established in the overall engineering design. The geometrics of a road—its calculated and measured movement through the landscape—are defined by its alignment and cross section. These, combined, determine both the design speed (the maximum safe speed for which the road is designed) and the posted speed (the maximum legal speed identified—generally lower than the design speed). Alignment is defined as both horizontal (movement to the left or right—a road’s curves) and vertical (movement up or down—the road’s hills or grades). Alignment is a principal determination of site distance (how far ahead the driver has a view of the pavement (a desired attribute)—hills or curves limiting site distance, for example). Cross section elements include the width of lanes and shoulders, slope or crown and superelevation (the “banking” of curves on higher speed roads).

Modern engineering concepts, if thoughtfully and appropriately applied to a historic road can greatly enhance safety with a minimal negative visual impact—the addition of superelevation to make a high speed curve safer, for example. Engineering design analysis may also assist in understanding the functioning of a historic road—demonstrating a road’s curves have a posted speed that exceeds the recommended design speed based on their geometry.

Modern design advances have enabled today’s automobiles to travel at average speeds well above those when many of our historic roads were constructed. Modern highway design with broad curves and superelevation further facilitates high speed driving. Accidents that occur at higher rates of speed are more likely to result in fatalities. Most traffic experts agree that reducing the posted speed, as an action to reduce speed, is generally ineffective—drivers will not arbitrarily lower their speed due to a new posting and enforcement, spotty at worst and expensive at best, can never be guaranteed twenty-four hours-a-day (raising a liability concern).

traffic calming
Traffic calming, a movement that began in Europe to reduce traffic speeds, has been widely implemented in the United States. As a principle, traffic calming introduces physical changes (speed humps, chicanes or “channels,” traffic circles or narrower lanes) to force a reduction in motorist speeds. While successful in reducing speeds on many roads throughout the country, the physical changes introduced through traffic calming may compromise the integrity of a historic road. Many historic roads however, by their design, embody elements of traffic calming. When looking at the safety of a historic road consider the possibility that original lane widths, narrow bridges and winding curves may be keeping speeds lower. It is also possible that the restoration or rehabilitation of historic cobblestone or brick pavements, due to their rough texture and audible tone, may aid in reducing or maintaining lower speeds.

Expectancy is a safety concept based on driver behavior and responses to changes in the roadway environment. Essentially, it suggests that when a driver is presented with a consistent, reliable and predictable driving experience he or she will respond prudently and appropriately. Thus both fifty miles of a narrow twisting mountain road and fifty miles of interstate highway both establish an expectancy that drivers instinctively respond to—caution and slower speeds on the mountain road compared to high speeds and confidence on the interstate. Safety problems tend to occur where an established expectancy is altered—a sharp curve or an entry ramp without an acceleration lane on a interstate highway, or a short segment of a wide straight road in the middle of the narrow winding mountain route (possibly sending the instinctive “signal” to motorists to increase their speed).

barriers and walls
Barriers and walls (guardrails, wire cables, wood posts, boulders and stone constructions) protect the automobile occupants from roadside hazards (fixed obstacles such as trees or bridge piers, or topographic dangers such as cliffs or ditches) and errant vehicles (an automobile crossing a median). Many historic barriers and walls, while constructed to the advanced engineering standards of their day, do not meet current guidelines for safety. Additionally many of the locations that today require a barrier or wall may not have had such installations historically. To improve safety without compromising historic integrity, a number of states and the federal government have redesigned historic barriers to meet modern crash testing requirements while maintaining the historic “look” of the original barrier. Design requirements for barriers and walls are based on the speed of the road and can vary significantly.

pedestrian and bicycle safety
The majority of our national safety policies are geared toward the occupants of motor vehicles. Yet pedestrian and bicycle fatalities hover between 15 and 20 percent of our annual traffic-related fatalities each year.* For historic roads associated with parks and recreation, urban thoroughfares or rural Main Streets a pedestrian and bicycle presence is part of the contemporary, and often historic, use. For these types of historic roads it is important to consider the impacts safety improvements will have on both the motor vehicle occupant and the pedestrian or bicyclist.

* source: National Transportation Safety Administration

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