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‏Capacity-Defined Capacity: Maximum hourly rate of vehicles or persons that can reasonably be expected to pass a point, or traverse a uniform section of lane or roadway, during a specified time period under prevailing conditions (traffic and roadway)
‏Prevailing Road Conditions Highway capacity depends on certain conditions as listed below, Road way characteristics: Traffic conditions: Control conditions: -Any change in the prevailing conditions changes the capacity of the facility Prevailing Road Conditions 1. Road way characteristics: Roadway factors include the following: Number of lanes, The type of facility and its development environment, Lane widths, Shoulder widths and lateral clearances. Design speed, Horizontal and vertical alignments, and Availabilitv of exclusive turn lanes at intersections 2- Prevailing Traffic Conditions They are not fixed but vary from hour to hour throughout the day. Hence the flows at any particular time are a function of The speed of vehicles The composition of the traffic streams OThe manner in which they interact with each other The physical features of the roadway itself Type of driver population Directional distribution of traffic

‏-prevailing controlConartions They refer to the types and specific design of control devices and traffic regulations present on a given facility. the location, type, and timing of traffic signals stop and yield signs lane use restrictions; and Oturn restrictions

‏IDEAL ROADWAY CONDITIONS Ideal roadway conditions assume good weather, good pavement conditions, users familiar, and: Uninterrupted flow o Passenger cars only in the traffic stream o Traffic lane 12 ft (3.6 m) wide o adequate shoulders and no lateral obstructions within 6 ft (1.8 m) of the edge of the pavement o Free-flow speed of 100 km/h for multilane highways o Level terrain
‏Capacity-Defined Capacity: Maximum hourly rate of vehicles or persons that can reasonably be expected to pass a point, or traverse a uniform section of lane or roadway, during a specified time period under prevailing conditions (traffic and roadway)

‏Prevailing Road Conditions Highway capacity depends on certain conditions as listed below, Road way characteristics: Traffic conditions: Control conditions: -Any change in the prevailing conditions changes the capacity of the facility Prevailing Road Conditions 1. Road way characteristics: Roadway factors include the following: Number of lanes, The type of facility and its development environment, Lane widths, Shoulder widths and lateral clearances. Design speed, Horizontal and vertical alignments, and Availabilitv of exclusive turn lanes at intersections 2- Prevailing Traffic Conditions They are not fixed but vary from hour to hour throughout the day. Hence the flows at any particular time are a function of The speed of vehicles The composition of the traffic streams OThe manner in which they interact with each other The physical features of the roadway itself Type of driver population Directional distribution of traffic

‏-prevailing controlConartions They refer to the types and specific design of control devices and traffic regulations present on a given facility. the location, type, and timing of traffic signals stop and yield signs lane use restrictions; and Oturn restrictions

‏IDEAL ROADWAY CONDITIONS Ideal roadway conditions assume good weather, good pavement conditions, users familiar, and: Uninterrupted flow o Passenger cars only in the traffic stream o Traffic lane 12 ft (3.6 m) wide o adequate shoulders and no lateral obstructions within 6 ft (1.8 m) of the edge of the pavement o Free-flow speed of 100 km/h for multilane highways o Level terrain

Level of Service (LOS) The LOS depending upon the travel speed and v/c ratio. o The ratio v/c can vary between 0 and 1. o Levels represent range of operating conditions defined by measures of effectiveness (MOE). o Letters designate each level, from A to F. o LOS A representing best operating conditions o LOS F representing worst operating conditions. Transportation 2-CE 342 Factors affecting LOS The factors affecting (LOS) can be listed as follows: Speed and travel time Traffic interruptions/restrictions Freedom to travel with desired speed Driver comfort and convenience Operating cost. Lateral obstruction, Lane width Traffic composition, Grade and Driver populationr











LOS A- Free Flow Free flow conditions. Vehicles are unimpeded in their ability to maneuver within the traffic stream. Incidents and breakdowns are easily absorbed. Free Flow with low volumes, densities and high speeds. Drivers can maintain their desired speeds with little or no delay. v/c 0.15
LOS B-Reasonably Free Flow Flow reasonably free Ability to maneuver is slightly restricted General level of physical and psychological to drivers is high comfort provided Effects of incidents and breakdowns are easily absorbed v/c 0.27 The lowest average vehicle spacing is about 330 fil 100 m) or 16 car lengths
LOS C- Stable Flow Flow Speeds at or near FFS Freedom to maneuver is noticeably restricted Queues may form behind any blockage. Lane changes more difficult Minor incidents will be absorbed, but will cause deterioration in service Acceptable delay. v/c 0.43
LOS D-Approaching Unstable Flow Speeds decline slightly with increasing flows Density increases more quickly Freedom to maneuver is more noticeably limited Minor incidents create queuing Drivers experience physical and psychological discomfort Tolerable delay. v/c 0.64 Vehicles are spaced about ease, 160 fi50m) or 8 car lengths.