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PIARC (World Road Association), founded in 1909 and comprising 125 member governments from all over the world, is the global forum for exchange of knowledge and experience on roads, road transport policies and practices. With consultative status to the Economic and Social Council of the United Nations, the Association is contributing to a stable and sustainable global development of the road and transport sector.

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Term of the Road Dictionary

maintained headroom

  • Language : PIARC Road Dictionary / English
  • Theme : Structures Tunnels
  • Definition : Vertical distance between the highest point of the carriageway and the lowest point of the vault (or of equipment under it), which shall be preserved at all times to ensure passage of authorized traffic. Notes: 1. This comprises the minimum headroom plus a comfort margin. 2. The maintained headroom must be at least equal to the minimum headroom plus the vertical clearance.

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