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Back to Road Safety Audits (RSA) |
In the pre-construction phase, the audit team has the greatest potential to improve safety as they are examining the design before a road facility is built. Pre-construction phase RSAs can be conducted on any proposed project that is likely to alter interactions between different road users or between road users and the road environment.
This chapter will discuss two stages of RSAs that may occur within the pre-construction phase:
As shown in Exhibit 3.1, RSAs may also be conducted at the planning stage; however, this version of the guideline does not provide details on how to conduct planning stage RSAs. Prompt list 1 provided at the end of this guideline lists the items that would be within the scope of a planning stage RSA .
If a land use development proposal forms part of the design or may impact the design or the adjacent road network, it should be included in the RSA . Prompt list 7 provided at the end of this guideline lists the items that would be within the scope of land use development proposal RSAs.
Preliminary design RSAs are conducted on the preliminary (functional) design drawings. At this stage, design drawings may show only general details regarding road alignment and the profile of the road along with typical cross-sections. Design drawings for intersections and interchanges should be at a larger scale to allow for closer scrutiny by the RSA team. A base map may show vertical contours, watercourses, and existing roads, structures, and property lines.
What to consider in preliminary design RSAs.
During preliminary design RSAs, the RSA team will not be able to see the actual layout of the site as it will appear upon completion, but should still conduct a field investigation.
The RSA team should see how the planned road improvement will tie in to the existing road network and examine adjacent roadways to determine how consistent the design will be from the perspectives of different road users. They should consider prevailing climatic conditions, surrounding vegetation, and topography.
At this point in the life of a project, fundamental decisions regarding route choice, the overall design, and layout of the project have already been decided.
However, the audit team may still suggest significant physical changes, such as horizontal and vertical alignment, provision of a median, lane and shoulder width, provision of bicycle lanes and sidewalks, and channelization. Access provided (driveways, intersections, interchanges) should be reviewed for upstream/downstream effects, potentially conflicting movements, and sight distances. Consolidation of access points may still be considered at this time.
If alternative options are still being considered, the RSA team should review each of the alternatives. Where significant land acquisition is involved in the project, the RSA should be conducted before acquisition is finalized in the event that the RSA team recommends significant changes to horizontal alignment that would require additional land.
What is the purpose of a preliminary design RSA ?
If staged implementation of the project is to be carried out, each stage should be considered as well as the transition between each stage. The ability of the design to accommodate any future widening, expansion, or extension should be considered.
A detailed design RSA is conducted before completion of the final design drawings (plans 60-80% complete) for the construction of a road facility. The project owner may consider providing intersection and interchange layouts at an even larger scale to allow for a more thorough examination. The base map will show in significant detail existing vegetation, vertical contours, watercourses, and existing roads and property lines at a large scale. Design drawings made available to the RSA team will be large scale and will show significant detail, as follows:
Information available in a detailed design
What is the purpose of a detailed design RSA ?
The audit team may wish to ask the project manager about any other details pertinent to the RSA that are absent from the design drawings. If alternative plans are still being considered, the audit team should review each alternative option as well.
During detailed design RSAs, if road grading has started, the audit team will have a greater opportunity to appreciate the layout of the roadway in the context of its location through a field investigation. They should see how the planned road improvement would tie in to the existing road network and examine adjacent roadways to determine how consistent the design will be from the perspective of road users.
Detailed design RSAs provide the last opportunity to change the design before actual construction of the road commences. Land acquisition may be finalized at this stage and will prevent the audit team from making any recommendations involving significant changes to road alignment or road cross section.
As with preliminary design RSAs, if staged implementation of the project is to be carried out, each stage should be considered as well as the transition between each stage. The ability of the design to accommodate any future widening, expansion, or extension should also be considered.
Prompt list 3 provided at the end of this guideline lists the items that would be within the scope of the RSA of the detailed design.
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