616.5 One-Lane, Two-Way Traffic Control (MUTCD Chapter 6E)
616.5.1 One-Lane, Two-Way Traffic Control – General (MUTCD Section 6E.01)
Standard. When traffic in both directions must use a single lane for a limited distance, movements from each end shall be coordinated.
Guidance. Temporary one-lane, two-way traffic control operations are considered on a case-by-case basis. One-lane, two-way operations should be avoided when hourly volumes exceed 600 vehicles per hour. When hourly volumes exceed 600 vehicles per hour or conditions in the following articles cannot be met, alternative construction methods should be considered, such as night work, shoulder improvements for maintaining two-way traffic, time restrictions for lane closures, construction during off-peak hours, detours, or diversions.
Provisions should be made for alternate one-way movement through the constricted section via methods such as flagger control, a flag transfer, a pilot car, or traffic control signals.
Control points at each end should be chosen to permit easy passing of opposing lanes of vehicles.
Provisions should be made for the control of movements from intersecting side roads or access points within a one-way, two-lane TTC zone (see TA-10).
Option. Individual residences along the highway within the work area may be personally contacted and informed of the process for entering and exiting their property.
616.5.2 Flagger Method (MUTCD Section 6E.02)
Guidance. Traffic should be controlled by a flagger at each end of a constricted section of roadway. One of the flaggers should be designated as the coordinator. To provide coordination of the control of the traffic, the flaggers should be able to communicate with each other orally, electronically, or with manual signals. These manual signals should not be mistaken for flagging signals. When more than one flagger is being used, all communication procedures should be clear before any flagging begins.
Support. Flagger segments are generally not longer than three miles for rural highways and one mile for urban highways. The maximum length is specified on the TTC plan so the contractor can properly stage the work.
616.5.3 Flag Transfer Method (MUTCD Section 6E.03)
Support. The driver of the last vehicle proceeding into the one-lane section is given a red flag (or other token) and instructed to deliver it to the flagger at the other end. The opposite flagger, upon receipt of the flag, then knows that traffic can be permitted to move in the other direction. A variation of this method is to replace the use of a flag with an official pilot car that follows the last road user vehicle proceeding through the section.
Guidance. The flag transfer method should be employed only where the one-way traffic is confined to a relatively short length of a road, usually no more than 1 mile in length.
616.5.4 Pilot Car Method (MUTCD Section 6E.04)
Option. A pilot car may be used to guide a queue of vehicles through the TTC zone or detour.
Pilot vehicles may be specified to supplement flaggers when the length of the one-lane, two-way operation exceeds one-half mile.
Guidance. The pilot car should have the name of the contractor or contracting authority prominently displayed.
Standard. The PILOT CAR FOLLOW ME (GO20-4) sign shall be mounted on the top or on the rear of the pilot vehicle (see EPG 616.8.35).
The pilot car operation shall be coordinated with flagging operations or other methods of control at each end of the one lane section of the work zone.
If an Automated Flagger Assistance Device (AFAD) (see EPG 616.12.2) is used in pilot car operations, the AFAD shall be operated by a flagger positioned near and within the line of sight of the AFAD. The AFAD shall not be left unattended at any time that the AFAD is being used.
Guidance. The access control and signing for each side road located within the work area of the one-lane, two-way operation should be determined as discussed in EPG 616.5.1. Where applicable, the signing sequence for the side road should be supplemented with the PILOT CAR IN USE WAIT & FOLLOW (GO20-4a) sign (see TA-10 for MoDOT internal use).
If temporary traffic control signals are used in pilot car operations and long wait times will be encountered by road users, consideration should be given to using signs to notify drivers of the wait time and/or pilot car operation, based on engineering judgment.
When a pilot vehicle is used, traffic delays should be limited to 15 minutes.
616.5.5 Temporary Traffic Control Signal Method (MUTCD Section 6E.05)
Option. Traffic control signals may be used to control vehicular traffic movements in one-lane, two-way TTC zones (see TA-12 and EPG 616.15).
Portable Signal Flagger Device (PSFD) Control. PSFDs are portable traffic control systems that may be used by the contractor to replace flagging operations for short-term lane closures on two-lane highways. In a typical flagging operation, a PSFD system requires four units with two units placed on either side of the roadway, in each direction. The primary benefit of the PSFD is the safety enhancement to the flaggers (see TA-10SPSFD).