El programa National Cooperative Highway Research Program (NCHRP) lanza una convocatoria para el desarrollo de modelos para el ” Development of Crash Prediction Models for Short-Term Durations” que podría ser utilizado, por ejemplo, en el caso de obras de mantenimiento.
Current crash prediction methods—such as those in the AASHTO Highway Safety Manual (HSM)—consist of safety performance functions (SPF), crash modification factors (CMF), and severity distribution functions (SDF). These tools use annual average daily traffic (AADT) data along with geometric and operational characteristics to predict annual average crash frequency of roadway sites. While these models have statistical merit, they do not allow users to accurately predict crashes for variable, short-term periods (e.g., peak periods, special events). This can be an issue for agencies wanting to assess the safety impacts of temporary works zones or time-of-day capacity changes (e.g., lane configuration or speed limit). The existing annual prediction convention also limits the models’ ability to quantify the effects of variables that fluctuate throughout the day (e.g., operating speeds, or operating speed variance). State departments of transportation require the ability to more accurately assess daily or hourly changes that could affect crash outcomes. There is a need for research to explore new data, revised aggregations, and newer statistical methods to effectively model highway safety on a daily, hourly, or other short-term basis.
The objectives of this research are to: (1) develop short-term crash prediction models to estimate the safety performance of roadways. Consideration should be given to specific geometric, operational, and exposure characteristics (e.g., detours, variable speed limits), and routes that experience short-term capacity changes (e.g., hard shoulder running, reversible lanes). (2) Identify explanatory variables measured over short durations. Include more precise measures of exposure other than AADT (e.g., peak hour volume, special event volume), and factors such as speed (including speed variability) to help predict crashes for varied periods of time. (3) Develop an implementation tool suitable for practitioner use.
Accomplishment of the project objective(s) will require at least the following tasks.
The NCHRP is seeking the insights of proposers on how best to achieve the research objectives. Proposers are expected to describe research plans that can realistically be accomplished within the constraints of available funds and contract time. Proposals must present the proposers’ current thinking in sufficient detail to demonstrate their understanding of the issues and the soundness of their approach to meeting the research objectives.
The research plan should: (1) include a kick-off teleconference with the research team and NCHRP convened within 1 month of the contract’s execution; (2) address the manner in which the proposer intends to satisfy the project objectives; (3) be divided logically into at least two phases that detail tasks necessary to fulfill the research objectives; (4) include appropriate milestones and interim deliverables; and (5) incorporate opportunities for the project panel to review, comment, and approve milestone deliverables.
The research approach should address, at a minimum, the following tasks, questions or concepts.
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