Realignment - Horizontal

Unexpectedly tight horizontal bends can lead to crashes when drivers try to negotiate them at high speed.

On narrow roads, vehicles may cross into the path of an approaching vehicle on tight bends, or they may travel onto shoulders and pedestrian areas.

There are several ways in which the horizontal alignment of a road may be modified to improve safety. These include increasing bend radius, providing transition bends (to facilitate the gradual transition of steering from straight sections of road to bends), removing compound bends or improving superelevation.

The horizontal alignment of intersection approaches may be realigned to improve sight distance or to reduce approach speeds and reinforce priority at the intersection (for example, at a Y-junction).

  • Reduced risk of head-on crashes.
  • Reduced risk of run-off-road crashes.
  • Better traffic flow.
  • Road realignment is costly and time consuming because it usually involves rebuilding a section of road.
  • Horizontal curve realignments require considerable design and construction effort. These projects may also require the purchase of land.
  • Horizontal realignments often include lane widening, shoulder improvement, and delineation treatments.

Benefits

  • Reduced risk of head-on crashes.
  • Reduced risk of run-off-road crashes.
  • Better traffic flow.

Implementation issues

  • Road realignment is costly and time consuming because it usually involves rebuilding a section of road.
  • Horizontal curve realignments require considerable design and construction effort. These projects may also require the purchase of land.
  • Horizontal realignments often include lane widening, shoulder improvement, and delineation treatments.

Did you know?

In March 2010 the United Nations General Assembly resolution proclaimed a Decade of Action for Road Safety 2011-2020.

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Treatment Summary

Costs
High
Treatment life
20 years +
Effectiveness
25-40%

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