Chapter 5 - Appendix F – Safety Analysis Concepts
Section 1: SII Calculators
Variable | Definition |
S | annual savings in preventable crash costs (equal to crash cost savings per year less annual maintenance costs), as determined by the above formula |
R | crash reduction factor (see following subsection for explanation) |
F | number of preventable fatal and incapacitating injury crashes (see following subheading for explanation) |
Cf | cost of a fatal or incapacitating injury crash (see following subheading for explanation) |
I | number of preventable non-incapacitating injury crashes (see following subheading for explanation) |
Ci | cost of a non-incapacitating injury crash (see following subheading for explanation) |
Y | number of years of crash data |
M | change in annual maintenance costs for the proposed project relative to the existing situation |
Q | annual change in crash cost savings, as determined by the above formula |
Aa | projected average annual Average Daily Traffic (ADT) at the end of the project service life |
Ab | average annual ADT during the year before the project is implemented |
L | project service life (see following subheading for explanation) |
B | present worth of project benefits over its service life, as determined by the above formula |
C | initial cost of the project. |
