RSA | Optioneering | Concept Design
The audit team was tasked with assessing risks associated with two layout options concerning lateral shifts through an intersection, arising from site constraints. The team focussed on the following issues:
General
- The approach horizontal and vertical alignment
- Observed driver speed and behaviour
- Driver expectations based on approach alignment
- Pavement surface condition
- Effect of options on approach sight distance or stopping sight distance
- Visibility of the approach to intersection, intersection, and beyond (alignment, line marking, signals, etc.)
- Road crossfall on approach and through the intersection
- Edge of road delineation
- Edge of road hazards
Specific
- The extent to which a lateral shift through an intersection is inherently more dangerous than a lateral shift in a mid-block, in general and in this setting.
- The extent to which the design in each option is a deviation to existing conditions or driver expectations both locally and from a road network perspective.
- Geometric principles including lateral deviation rates.
The audit assisted the project by helping to understand the likely risks for both options, and possibly treatment options.
