The following terms are utilized in the Alternative Design application.

formerly known as Part C CMFs—(see crash modification factors)

Adjustment factors are similar to crash modification factors, with one difference, adjustment factors are created with and correspond to a single safety performance function (SPF). Standard CMFs do not correspond to a single SPF.

A lane or set of lanes at an intersection that accommodates all left-turn, through, and right-turn movements from a given direction.

The default set of conditions for each SPF. The base conditions are the conditions for which each SPF was developed. The base condition is different for each SPF and is specified in the HSM. The base condition is not necessarily a perfect or ideal condition; it is a reflection of the data available to the statisticians at the time the SPF was developed.

A factor to adjust crash frequency estimates produced from a safety prediction procedure to approximate local conditions. The factor is computed by comparing existing crash data at the state, regional, or local level to estimates obtained from predictive models.

the total roadside border area, starting at the edge of the traveled way, available for use by errant vehicles.

An index of how much crash experience is expected to change following a modification in design or traffic control. CMF is the ratio between the number of crashes per unit of time expected after a modification or measure is implemented and the number of crashes per unit of time estimated if the change does not take place.

the level of injury or property damage due to a crash, commonly divided into categories based on the KABCO scale (See KABCO).

an interchange that results in two or more closely spaced surface intersections, so that one connection is made to each freeway entry and exit, with one connection per quadrant.

An estimate of long-range average number of crashes per year for a particular type of roadway or intersection.

Four‐lane divided roadways (for arterials it includes segments with a raised or depressed median)

An intersection of a rural two-lane, two-way road and two minor roads. A stop sign is provided on both minor road approaches to the intersection.

An intersection of a major road and two other roads of the same type. Signalized control is provided at the intersection by traffic lights.

intersections that consist of structures that provide for the cross-flow of traffic at different levels with- out interruption, thus reducing delay, particularly when volumes are high.

a crash that occurs at the intersection itself or a crash that occurs on an intersection approach within 250 ft (as defined in the HSM) of the intersection and is related to the presence of the intersection.

An injury scale developed by the National Safety Council to measure the observed injury severity for any person involved as determined by law enforcement at the scene of the crash. The acronym is derived from (Fatal injury (K), Incapacitating Injury (A), Non-Incapacitating Injury (B), Possible Injury (C), and No Injury (O).) The scale can also be applied to crashes: for example, a K crash would be a crash in which the most severe injury was a fatality, and so forth.

the portion of a divided highway separating the traveled ways from traffic in opposite directions. Types include:

An island in the center of a road that physically separates the directional flow of traffic and that provides pedestrians with a place of refuge and reduces the crossing distance of a crosswalk.

the lower volume street controlled by stop signs at a two-way or four-way stop-controlled intersection; also referred to as a side street. The lower volume street at a signalized intersection.

a highway with at least two lanes for the exclusive use of traffic in each direction, with no control, partial control, or full control of access, but that may have periodic interruptions to flow at signalized intersections.

A lane added to improve passing opportunities in one or both directions of travel on a two-lane highway.

a person traveling on foot or in a wheelchair.

considers the clear zone in conjunction with the roadside slope, roadside surface roughness, recoverability of the roadside, and other elements beyond the clear zone such as barriers or trees. As the RHR increases from 1 to 7, the crash risk for frequency and/or severity increases.

A portion of a road that has a consistent roadway cross-section and is defined by two endpoints.

devices designed to give strong auditory and tactile feedback to errant vehicles leaving the travel way.

an equation used to estimate or predict the average crash frequency per year at a location as a function of traffic volume and in some cases roadway or intersection characteristics (e.g., number of lanes, traffic control, or type of median).

A portion of the roadway contiguous with the traveled way for accommodation of pedestrians, bicycles, stopped vehicles, emergency use, as well as lateral support of the subbase, base, and surface courses.

the deviation from an intersection angle of 90 degrees. Carries a positive or negative sign that indicates whether the minor road intersects the major road at an acute or obtuse angle, respectively.

An area with a mixture of densities for housing and employment, where high-density non- residential development is intended to serve the local community.

An arterial consisting of three lanes including a center two-way left-turn lane (TWLTL).

An intersection of a major road and a minor road. A stop sign is provided on the minor road approach to the intersection only.

A roadway consisting of two lanes with a continuous cross-section providing two directions of travel in which the lanes are not physically separated by either distance or a barrier.

An area typified by high densities of development or concentrations of population, drawing people from several areas within a region.

the average number of vehicles passing a point on a roadway in a day from both directions, for all days of the year, during a specified calendar year, expressed in vehicles per day.