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OCR for page 60
60 This concept seems well-known to transit agency personnel ponents to be evaluated at this stage of the project include as it was raised by local staff at several of the site visit work- intersection details, lane markings, signals/signs, lighting, geo- shops held for this project. However, the participants gener- metric layout, roadside clearances, and provisions for vul- ally believed that more could have been done during design to nerable road users. Field investigations conducted during the improve safety on their various systems. It is certainly possible detailed design phase of the project can provide the safety that cost or other constraints had an impact on safety features audit team with an enhanced understanding of the project in the design stages. layout and potential interactions with surrounding trans- portation networks, particularly if some preparatory work has already begun. If a previous safety audit has been conducted, Preliminary Design Stage any issues identified or overlooked during that audit should be Safety audits during the preliminary design phase should be re-examined at this stage of the project. If applicable, the safety conducted once critical decisions regarding route choice and audit team should assess the potential impact of construction project design/layout have been determined. The safety audit staging and traffic detour plans on the surrounding networks. should use both preliminary design drawings and site visits in the evaluation of a design. If multiple alternatives are still under In-use Stage consideration, or if the project will be implemented in stages, the safety of each alternative, stage, or transition between stages A safety audit of an existing roadway/railway seeks to iden- should be evaluated separately. tify where collisions will occur and their potential severity. This The primary objective of a safety audit is to evaluate the rel- is accomplished through an examination of available infor- ative safety of the proposed design based on all information mation, including as-built drawings, previous safety audits (if available. Typical components to be evaluated include applicable), volume data, speed data, signal-timing plans, horizontal/vertical alignment, sight distances, typical cross sec- etc. Unlike safety audits conducted during the design phases, tions, intersection/interchange layouts, potential conflict observations collected from site visits can be used to diagnose points, and property accesses. Design consistency and user areas of elevated safety risk. Physical evidence such as skid expectations should also be assessed. Any departures from marks, scuff marks, and damage to surrounding features can accepted design standards and their effect on safety should be be used to identify potential hazards. In addition, the audit noted. In addition, adequate safety should be ensured in areas team can observe the behavior of various users interacting where multiple project elements meeting minimum standards with the transportation facility and key features such as traffic interact. The safety audit should be conducted before land control devices, and assess the potential impact on safety. acquisition in case significant changes to the design are A safety audit differs from a safety review in that it is pro- required. During the site visit(s), the audit team should exam- active and not reactive. While safety reviews are often initi- ine the surrounding transportation network (roads, sidewalks, ated in response to a high number of incidents at a specific paths, etc.), and ensure that the proposed design is consistent location, a safety audit seeks to identify potential problems from the perspective of all potential users. The ability to before they occur. Therefore, a safety audit does not rely prima- accommodate future design improvements should also be rily on collision history to determine safety issues. Although considered. collision data may be useful to supplement the findings of the Conducting a safety audit during the preliminary design safety audit, it may not reflect current and future conditions, phase can avoid wasting valuable design time during the and should not be relied upon too heavily. detailed design phase. LRT collisions are relatively infrequent events and there- fore do not necessarily reflect all the safety issues at a site. The collision history may lead staff to early conclusions and rec- Detailed Design ommendations that, while not incorrect, may overlook other Safety audits during the detailed design phase should be safety concerns that exist but have yet to be implicated in an conducted when detailed design drawings and sufficiently incident. The safety audit team may choose not to review the detailed base maps are available. The base map should include collision data until they have developed recommendations all relevant environmental and topographical features in addi- based on all other available information in order to avoid tion to existing infrastructure. Similar to the safety audit dur- incorporating bias in the analysis. ing the preliminary design phase, all alternative stages and Inspectors should also be mindful of any potential changes transitions between stages should be evaluated separately. to the function or classification of the transportation facility A safety audit conducted during the detailed design phases since its construction. Changes might include increased traf- will benefit from access to information not available at earlier fic volumes and changes in vehicle mix, adjoining land use, or stages of the project, but any significant changes to the design the intensity of development. Elements of the facility that were will require greater expenditure to implement. Typical com- reasonable and effective in design may no longer serve their