14.5 Continuous Green T-Intersection (CGT)
14.5.1 Overview
A Continuous Green-T (CGT) is a T-intersection design where one major street direction of travel (the top side of the “T”) can pass through the intersection without stopping and opposite major street direction of travel is typically controlled by a traffic signal.
Left-turn vehicles from the side street use a channelized receiving lane on the major street to merge onto the major street. A CGT intersection is typically signalized but can also be designed without a traffic signal. Intersections of this type are common and have performed well in other states including Florida, Utah, Nevada, and New York. CGT intersections reduce delay at high-volume locations by removing the need to stop both directions of mainline traffic to accommodate left-turns.
A CGT is also known as:
- Turbo-T intersection;
- High-T intersection; and
- Seagull intersection.
shows an example of a GCT intersection.
Figure 14-15: Example of a CGT Intersection
Source: Innovative Intersections – Continuous Green-T (CGT) (VDOT)
Benefits of a CGT include:
- Improved safety –channelization of left-turn vehicles from the side street reduces the potential for angle crashes.
- Increased efficiency –because one direction of travel on the major street is free-flow, more green time can be provided to the other movements, reducing delay at the intersection.
- Free-flow in one direction –one direction of travel on the major street never stops, which improves traffic signal synchronization and reduces corridor travel times.
Conditions where a CGT may not be suitable include:
- If there is another intersection beyond the CGT that experiences congestion. This may cause spillback into the CGT and prevent the resultant free-flow;
- Intersections where pedestrians need to cross the major street; and
- Highly developed areas. The CGT may restrict access to existing driveways on the continuous flow lanes.
14.5.2 Design Considerations
A CGT should be considered in the following instances:
- 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 major street opposite the side street; and
- A limited number of pedestrian crossings across the major street or with an alternative pedestrian crossing location nearby.
Refer to
for more information on the safety performance of the CGT intersection.
14.5.3 Sight Distance
Sight distance for a CGT is similar to a standard intersection. Provide appropriate sight distance and lighting for approaching motorists to see activity at the crosswalk, as well as sight distance for pedestrians to see oncoming traffic. Stopping sight distance for the approaching motorists and sight distances for the pedestrians approaching the potential oncoming automobiles must be clear of obstructions and provide sufficient visibility for various users.
14.5.4 Access Management
From an access management standpoint, the CGT intersection will restrict access to driveways near the intersection for vehicles turning left into the top side of the T. Driveways with parallel roads may be provided beyond the intersection to provide access. Driveways near the intersection may also cause weaving.
14.5.5 Pedestrian and Bicyclist Considerations
Due to the continuous flow of traffic on the top side of the T, a CGT does not typically allow pedestrians to cross the major road. Traffic signal equipment can be installed to stop traffic along the continuous green cycle to accommodate pedestrians and bicyclists. If necessary, provide crosswalks and adequate sight distance and lighting for safety. Bicyclists may navigate the CGT either at the crosswalks provided, or by using bike lanes along the major road.