4.02 Construction and Contract Methods
The WZSM Policy ensures all work zone impacts are appropriately identified, mitigated, and managed on a systematic basis. Work zone and traffic management design strategies should provide the highest level of safety, mobility, and constructability.
A total road closure may be the best example of this approach. Generally, this is the safest, most mobile and constructible work zone approach. Workers and road users are separated and exposed to fewer hazards, road users are not delayed through a restrictive work zone, and construction may proceed without accommodating traffic.
A full closure may be a desirable starting point for some projects based on the project specifics. The time is dramatically reduced, and safety and overall quality of the project are improved. However not all project are candidates for this strategy for a number of reasons:
- Lack of alternate route capacity
- Lack of adequate detours
- Severe congestion throughout a widespread area
- Local traffic access to residences and businesses
- Other traffic management and cost issues
A more common and acceptable approach is a combination of short-term closures and partial width stages. This strategy uses a TTCP that positively separates and protects workers and road users, while accommodating efficient work operations and traffic mobility.
Some projects may benefit from efficiently staged and protected work operations versus routine lane closures that close and open each day.
When developing the TMP it is important to consider the constructability of the project based on the preferred MOT scheme. A TMP should be developed in conjunction with the construction staff to ensure projects are buildable and safe. This includes reviewing work schedules, production rates, and industry means and methods. If the preferred MOT places too many restrictions and limitations on constructability, there may be negative consequences to the costs and quality. Several construction and contracting strategies are listed in Chapter 2 Transportation Management Plan.
It is important to remember there are practical limits to work zone strategies. Mobility and safety benefits that are relatively short term may not be practical if the cost of implementation offsets a significant portion of the benefit. Some projects may benefit from a wider review and discussion on possible work zone strategies, such as:
- Value Engineering Study
- Constructability Study
- Industry plan reviews
- Work Zone Construction Peer Review
- Maintenance of Traffic Meetings
- Traffic Survey/Study
- Innovative contracting
- Governmental agency and special event coordination meeting
Constructability is a key element in a successful work zone strategy. Issues of material selection, production rates, and work operation efficiencies have a direct tie to the feasibility of the strategy. The following successful strategies have been implemented:
- Short duration closures (weekend, week, or a combination)
- Continuous weekday closure
- Weekend closure
- Nighttime and weekend lane closures
- Rolling 15-min short term freeway closures
These strategies use specific materials such as quick-curing concrete, accelerated work schedules, prefabricated structure components, onsite mix plants, etc., and are based on actual production rates. Work zone strategy development is a dynamic process that continues as project information and design features are developed. There may be many factors involved with strategy development.
FHWA provides additional guidance and a comprehensive table of work zone impact management strategies to consider in the development of a TMP.
FHWA document links:
- Developing and Implementing TMPs (TMPs) for Work Zones
- FHWA Document Section 4.0
- FHWA Document Appendix B
MDOT also provides a best practice folder which may be found on ProjectWise (TMP Best Practices). For access to this folder please contact the WZMU.
