What Is a Taper?
A plain-English explanation of tapers in work zones: what they do, the main types, and why taper length is tied to traffic speed.
Published June 24, 2026
A taper is a line of channelizing devices set at an angle that guides traffic out of its normal path, such as merging drivers out of a closed lane. It is one of the most important parts of a work zone because it shapes how smoothly traffic moves past the work.
This article explains what a taper does, the common types, and why its length depends on traffic speed.
What a Taper Does
A taper moves traffic from where it normally travels to where it needs to go around the work, using a gradual angle rather than an abrupt shift. Drivers follow the line of cones or drums into the open path.
A taper that is too short for the speed forces a sudden merge; one set correctly gives drivers time to react and move over smoothly.
Common Types of Tapers
Different situations call for different tapers, though they all share the same idea of guiding traffic at an angle.
- Merging taper: moves traffic out of a closed lane into an adjacent open lane.
- Shifting taper: moves traffic sideways into a shifted path without reducing lanes.
- Shoulder taper: guides traffic past work on the shoulder.
- Downstream taper: eases traffic back to normal lanes after the work.
Why Taper Length Depends on Speed
The faster traffic is moving, the more distance drivers need to merge safely, so taper length increases with speed. This is why the same lane closure needs a much longer taper on a highway than on a low-speed street.
The approved plan specifies taper lengths for the location, and matching them in the field is part of building the closure correctly.
Related Terms
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