seven applicable countermeasures, where multiple countermeasures are applicable to the same crash type. For those countermeasures, a combined CMF is calculated and applied to crashes of that same type. Countermeasures with no applicable CMF do not count towards the maximum of three.
Table 4: Countermeasures Combination Example
Countermeasure Crash Type Original CMF Combined CMF
A
All
0.65
0.23
B
All
0.35
C
Pedestrian 0.87
D
Pedestrian 0.40
0.24
E
Pedestrian 0.68
F
Pedestrian --
G
Bike
0.47
0.47
Benefit-Cost Analysis
Benefit cost analysis compares the overall benefits of recommended improvements to a project’s total cost over a specified time period. This benefit-cost ratio (B/C) is provided for each recommended improvement. Higher B/C ratios indicate higher potential returns for safety improvements. This analysis can assist the City’s implementation decision-making. The process of calculating the B/C ratio begins with the identification of a horizon year (typically a 20-year project life span). The benefit of a project is the monetized value of crashes 4 that would be prevented over the project's lifespan. The number of crashes prevented is computed assuming a consistent crash rate as traffic grows in the future without safety improvements. The crash modification factor is then applied to calculate future year crashes over the 20-year period with safety improvements. The cost is the total initial cost of the project, which includes the construction cost and an allowance for survey and engineering, and the maintenance cost over a 20-year project lifespan. The cost estimates were developed using bid tab data provided by the City. All costs are in present (2025) values.
To calculate the benefits, the following steps were taken:
4 TxDOT crash costs by severity: https:/ftp.txdot.gov/pub/txdot-info/trf/hsip/sii-calculator.xls
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