Iowa Local Technical Assistance Program

About the research

Different types of temporary barrier rail (TRR) are utilized for head two lane two way (TLTW) work zone configurations, including tubular markers, temporary barrier, or barrels. Each has different advantages/disadvantages in terms of cost, safety, mobility, and ease of application/removal.  Channelizers are the most cost effective and easy to place or move in a work zone. However, in high speed operations, they provide minimal separation of opposing vehicles.  Concrete median barriers, on the other hand, provide full separation and protection from on-coming vehicles but are significantly more expensive and not as easily moved. Additionally, they occupy more of the travel lane which may restrict traffic flow. A brief literature review did not yield any information pertaining to guidelines or safety impacts although both Iowa, Minnesota, and other states have been using the devices. As a result, agencies have little guidance on when and where different configurations should be used.

The objective of this research is to assess when each type of barrier should be used in TLTW work zones and to develop guidelines for their use. This includes evaluation of the safety and operational impacts as well as an assessment of the tradeoffs in terms of benefit and cost.