Mid-America Transportation Center
Date of this Version
2017
Document Type
Article
Citation
Paper prepared for presentation at the Innovations in Road Safety Session
of the 2017 Conference of the Transportation Association of Canada St. John’s NL
Abstract
Manitoba Infrastructure (MI) desired a new, tall concrete median barrier capable of satisfying the Test Level 5 (TL-5) safety requirements of the Manual for Assessing Safety Hardware (MASH). It needed to fit within the footprint of an existing F-shape median barrier located in a narrow median. It also was required to address headlight glare from opposing traffic. The barrier was designed with a height of 1,250 mm, a maximum width of 600 mm and to resist a load of 845 kN applied at the top of the barrier. The Manitoba Constrained-Width, Tall Wall was optimised to withstand the design load while minimising the amount of steel reinforcement. Variations of the barrier were developed, including a bridge rail and a roadside barrier.
The bridge rail was considered to be the critical design due to its narrow width and anchorage to a relatively thin, cantilevered bridge deck. Thus, one full-scale vehicle crash test was conducted on the bridge rail system to verify the entire family of barriers. A vertical back barrier (45.72 m long) was constructed. It had a height of 1,250 mm and widths of 450 mm at its base and 250 millimetres at the top. The upstream half of the barrier (22.86 m) was constructed on a simulated bridge deck that was 280 mm thick. A gap in the bridge rail was constructed that was 168 mm wide and a gap in the bridge deck that was 19 mm wide; these were placed mid-span to simulate an expansion joint. A steel cover plate was placed over the barrier joint to prevent vehicle snag. During the test, the tractor trailer impacted just upstream from the joint and was safely redirected. The barrier sustained minor damage in the form of cracks and spalling.
Anchorage options were developed for use with the TL-5 barrier system, including a foundation slab and an independent footing. Transition systems were also detailed for the connection of the TL-5 median barrier to various other new and existing barrier shapes. Finally, Manitoba Infrastructure developed a full series of barrier systems for median and roadside conditions that will provide designers many options to create construction drawings for their projects that are specific for their site(s).