Continuous Green-T (CGT)
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Continuous Green-T (CGT)

Innovative Intersections

Aerial view of a Continuous Green‑T (CGT) intersection at Thunder Drive and Callaghan Road, showing a three‑leg layout where the curved major roadway maintains uninterrupted through traffic while the side street connects via dedicated turn lanes.

CGT Intersection at Thunder Drive and Callaghan Road in San Antonio, Texas

Source: Nearmap

What is a CGT

Blue line icon of a continuous green T-intersection (C‑G T). The top horizontal roadway has two lanes with arrows pointing to the left. From the middle of the top road, a curved channel guides traffic into a single downward lane, shown with a straight arrow pointing down. The layout emphasizes continuous flow for left-turn movements without stopping.

A Continuous Green-T (CGT), also known as a High-T, is a three-leg innovative intersection. This configuration enables uninterrupted traffic flow on one side of the major roadway while accommodating left turns on to and off the minor road. CGT’s may be either signalized or unsignalized.

Diagram of a Continuous Green‑T (CGT) intersection with navigation guidance, showing uninterrupted through travel on the main road, channelized left‑turn merge from the side street, and typical pedestrian and right‑turn movements.

Continuous Green-T Diagram with navigation guidance

Source: VDOT, used with permission

Design principles

The CGT is characterized by the following basic principles:

Blue circular traffic symbol displaying a white infinity-shaped loop, representing continuous flow of traffic with no stops or signal interruptions.

Continuous Flow

Through movements are uninterrupted on the far side of the major roadway.

Blue circular traffic sign displaying a white left-turn arrow, indicating that vehicles must turn left at this location.

Separated Lefts

Left-turn lane(s) are provided on the major roadway, and an acceleration/merge lane is provided to receive lefts from the minor roadway. 

Blue circular traffic symbol displaying a white T-shaped road layout, indicating a T‑intersection where the roadway ends at a cross street.

T -Intersection

CGTs are designed to be used at T-intersections.

Design characteristics

Common to all CGTs

Pedestrian crossings along the major roadway are typically discouraged.

Raised medians are recommended to help channelize drivers and discourage incorrect movements. 

Left-turning vehicles from the minor roadway require acceleration lanes to merge safely with the major roadway.

Site dependent

Depending on the capacity analysis, CGTs may be signalized or unsignalized.

Continuous major roadway through-lanes may feature green through-arrow signalization.

Can cause driveway access limitations.

When to consider a CGT

  • Intersections with three legs.
  • Heavy through traffic volumes on the major street.
  • Moderate to low left-turn traffic volumes on the side street.
  • No driveways along the free-flowing side of the major street.
  • Pedestrian crossings across the major street are not required, or with an alternative pedestrian crossing location nearby.

CGT limitations

  • Restricts pedestrian crossings along the major street.
  • Increased intersection length for the receiving acceleration lane on the major street.
  • Increased cross-sectional width for the speed change lanes and the center median.
  • Specifically applies to three-legged intersections only.
  • May not be feasible in close proximity to adjacent intersections.
Aerial view of a Continuous Green‑T (CGT) intersection at Bicentennial Boulevard and Lark Boulevard, showing a three‑leg layout where the major roadway carries uninterrupted through traffic while the side street connects via channelized turn movements.

CGT Intersection at Bicentennial Boulevard and Lark Boulevard in McAllen, Texas

Source: Nearmap

Benefits of CGTs

  • Reduces the number of left-turn and crossing conflict points, resulting in a reduction of angle, injury, and total crashes.
  • Implementation of CGT’s cumulatively reduced angle crashes at the treated intersections by 96.8 percent, injury crashes by 70 percent, and total crashes by 60 percent (FHWASA09016)
  • Reduce delays at high-volume intersections by ~10%. (Litsas, S. and Rakha, H.)
  • Free flow movement simplifies traffic signal phasing, reducing overall delay.
  • The far side of the major street can operate uninterrupted, improving overall corridor travel times.
  • Studies have shown that continuous green-T intersections are a cost-effective alternative to the traditional signalized T intersection. (FHWA-HRT-16-036)

Educational materials

Videos

VDOT’s Continuous Green T (Signalized)
VDOT’s Continuous Green T (Unsignalized)

Additional resources

Have questions about CGTs? Please reach out!
innovative.intersections@txdot.gov