Types of Lanes
Through Lanes vs Auxiliary Lanes
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Overview
Overview
Lanes are designed to be used by a single line of vehicles and help guide drivers to minimize traffic conflicts and congestion. There are two general types of lanes used in the Highway Performance Monitoring System (HPMS) report: through lanes and auxiliary lanes.
Through Lanes
Through Lanes
A though lane is a lane on a roadway that extends through at least two intersections. If a lane ends at or before the second intersection, it is typically not considered a through lane. Through lanes do not include ramps or auxiliary lanes (see below).
Auxiliary Lanes
Auxiliary Lanes
Auxiliary lanes include portions of a roadway that do not accommodate through traffic. Unlike through lanes, auxiliary lanes do not pass through more than two intersections. Below are examples of auxiliary lanes.
Turning Lanes
Lanes that allow right or left turns off of a roadway
Parking Lanes
A lane on a roadway reserved for vehicle parking
Shoulders
Found on the sides or in the centerline area of most roadways, shoulders are generally reserved for vehicles that must stop due to emergency issues so they do not interfere with ongoing traffic
Frontage Road Lanes
Lanes that run parallel to and accommodate traffic from nearby highways, like interstates and freeways
Collector-Distributor (CD) Lanes
A CD lane separates freeway through-traffic from other vehicles that are exiting or entering the freeway.
See how CD lanes will be used in the redesigned I-10 Broadway Curve Area.
Weaving Lanes
Lanes used for incoming ramp traffic and outgoing highway traffic to merge, or weave, around each other
Source: Caltrans
Acceleration/Deceleration Lanes
Lanes that allow traffic to accelerate or decelerate to safely match the speed limit of the roadway that they are about to merge onto
Truck Climbing Lanes
Lanes added to roadways with steep uphill grades, allowing slower-moving vehicles to move out of the way of faster moving traffic
Toll Collection Lanes
Lanes used to direct traffic to or from a toll booth. Note, Arizona does not have toll roads.
Why the Distinction Between Lane Types is Important?
Why the Distinction Between Lane Types is Important?
Different items in the federal HPMS report use the different lane types in their calculations. For example, Lane Miles and Certified Public Mileage (CPM) only use through lanes. However, reports that use maintainance lane miles, such as the State Highway System Log, use both through lanes and auxiliary lanes.
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