Chapter 4G. Traffic Control Signals for One-Lane, Two-Way Facilities

Section 4G.01 Application of Traffic Control Signals for One-Lane, Two-Way Facilities

Support:
A traffic control signal at a narrow bridge, tunnel, or roadway section is a special signal that assigns the right-of-way for vehicles passing over a bridge or through a tunnel or roadway section that is not of sufficient width for two opposing vehicles to pass reasonably safely.

Temporary traffic control signals (see Sections 4D.20 and 6F.80) are the most frequent application of one-lane, two-way facilities.

Guidance:
Sight distance across or through the one-lane, two-way facility should be considered as well as the approach speed and sight distance approaching the facility when determining whether traffic control signals should be installed.

Option:
At a narrow bridge, tunnel, or roadway section where a traffic control signal is not justified under the conditions of Chapter 4C, a traffic control signal may be used if gaps in opposing traffic do not permit the reasonably safe flow of traffic through the one-lane section of roadway.

Section 4G.02 Design of Traffic Control Signals for One-Lane, Two-Way Facilities

Standard:
The provisions of Chapter 4D shall apply to traffic control signals for one-lane, two-way facilities, except that:

Durations of red clearance intervals shall be adequate to clear the one-lane section of conflicting vehicles.
Adequate means, such as interconnection, shall be provided to prevent conflicting signal indications, such as green and green, at opposite ends of the section.

Section 4G.03 Operation of Traffic Control Signals for One-Lane, Two-Way Facilities

Standard:
Traffic control signals at one-lane, two-way facilities shall operate in a manner consistent with traffic requirements.

When in the flashing mode, the signal indications shall flash red.

Guidance:
Adequate time should be provided to allow traffic to clear the narrow facility before opposing traffic is allowed to move. Engineering judgment should be used to determine the proper timing for the signal.