8.04 Work Zone Durations
(Updated 5/28/2021)
Maintaining safe work and road user conditions is a paramount goal in all work zones.
Work duration is a major factor in determining the number and types of devices needed for TTC. The duration of an activity is defined by the length of time an activity occupies a location.
The five categories of work type and their duration at a location are defined in MMUTCD section 6G.02, and are summarized as follows in Table 8-1:
Table 8-1: Work Durations
| Category | Work Duration |
|---|---|
| Long-term Stationary | Work that occupies a location more than 3 days. |
| Intermediate-term Stationary | Work that occupies a location more than one daylight period up to 3 days, or nighttime work lasting more than 1 hour. |
| Short-term Stationary | Daytime work that occupies a location for more than 1 hour within a single daylight period. |
| Short Duration | Work that occupies a location up to one hour. |
| Mobile | Work that moves intermittently or continuously |
8.04.01 Long-Term Stationary Work
There is adequate time to install a full range of TTC procedures and devices. These may include channelizing devices, temporary roadways, and temporary traffic barriers.
Since this work will extend into nighttime, retroreflective and/or illuminated devices must be used.
8.04.02 Intermediate-Term Stationary Work
In intermediate-term stationary work zones, it may not be practical to use procedures or devices that would be desirable for long-term stationary TTC zones, such as altered pavement markings, temporary traffic barriers, and temporary roadways. The increased time to place and remove these devices in some cases could significantly lengthen the project, thus increasing exposure time and risk to employees. Elaborate temporary traffic control measures may not be justifiable based on duration of work.
If this work will extend into nighttime hours retroreflective and/or illuminated devices must be used.
8.04.03 Short-Term Stationary Work
Most maintenance and utility operations are short-term stationary work. Work zone traffic control measures should be provided in a manner that considers the amount of time that work will be performed.
The roadway speed, volume, and work type should be used to determine what level of TTCD are needed to safely complete the work. If additional information is needed to determine what should be used contact the local TSC representative.
8.04.04 Short Duration Work
Compared to stationary operations, mobile and short-duration operations are activities that might involve different treatments. Devices having greater mobility might be necessary such as signs mounted on trucks. Devices that are larger, more imposing, or more visible can be used effectively and economically. The mobility of the TTCDs is important.
During short-duration work, it often takes longer to set up and remove the TTC than to perform the work. Workers also face hazards in setting up and taking down the TTC. Since the work time is short, delays affecting road users are significantly increased when additional devices are installed and removed.
8.04.05 Mobile Work
Mobile operations often involve frequent short stops for activities such as litter cleanup, pothole patching, or utility operations, and are similar to short-duration operations.
Mobile operations also include work activities where workers and equipment move along the road without stopping, usually at slow speeds. The advance warning area moves with the work area.
Channelizing devices to delineate open and closed lanes must be used at 50’ spacing when workers are outside of their vehicles in a existing lane while in a mobile operation is occurring during the nighttime hours. An example of such an operation is the layout of concrete patches.
Mobile operations must have appropriate warning devices on the equipment (high-intensity rotating, flashing, oscillating, or strobe lights, signs, or special lighting), or must use a separate vehicle with appropriate warning devices.
When mobile operations are being performed, a shadow vehicle equipped with an arrow board or a sign should follow the work vehicle, especially when vehicular traffic speeds or volumes are high. Where feasible, warning signs should be placed along the roadway and moved periodically as work progresses.
Under high-volume conditions, consideration should be given to scheduling mobile operations work during off-peak hours.
