9_27_11_HSM_SPF_CMF - Crash Prediction, How? You are tasked...

Info iconThis preview shows pages 1–15. Sign up to view the full content.

View Full Document Right Arrow Icon
Crash Prediction, How? You are tasked with assessing the possible safety benefits of the RLC on I/S of Stadium & Providence How would you go about it? What data would you need to collect? How much data would you need? What would you do with such data? CE4130 Transportation Safety 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Crash Prediction, How? CE4130 Transportation Safety 2
Background image of page 2
Crash Prediction, How? CE4130 Transportation Safety 3
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
HSM Prediction Structured methodology to estimate expected average crash frequency by total crashes, crash severity, or collision type of site, facility or network for a given time period, geometric design and traffic control features, and traffic volumes (AADT) CE4130 Transportation Safety 4
Background image of page 4
HSM Prediction Method also allows for crash estimation in situations where no observed crash data is available or no predictive model is available CE4130 Transportation Safety 5
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Summary of HSM Mechanics Prediction for a specific site type Statistical model developed from similar sites data Adjusted to for specific site and local conditions Empirical Bayes Method Combine estimation from statistical model with observed crash frequency at the specific site EB Method not apply if no observed data CE4130 Transportation Safety 6
Background image of page 6
HSM Organization CE4130 Transportation Safety 7 Intro Roadway Safety Management Predictive Methods Crash Modification Factors
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
SAFETY PERFORMANCE FUNCTION (SPF) CE4130 Transportation Safety 8
Background image of page 8
HSM Terminology Safety Performance Functions (SPFs) Statistical “base” models Used to estimate average crash frequency for a facility type with specified base conditions Based on regression CE4130 Transportation Safety 9
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Regression What is it? Is it a relapse to a less perfect or developed state? CE4130 Transportation Safety 10
Background image of page 10
Regression Given a set of data Finds a function of independent variables that best fit that data Regression could be linear or nonlinear Regression estimation methods: Least squares method minimizes the sum of squares residuals (observed – expected from function) Maximum Likelihood CE4130 Transportation Safety 11
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Example of Simple Linear Regression (Least Squares) CE4130 Transportation Safety 12 What is a “best fit” line through 5 pts.?
Background image of page 12
Example of Simple Linear Regression (Least Squares) Y=-8.098+0.19x CE4130 Transportation Safety 13
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Negative Binomial (NB) Regression CE4130 Transportation Safety 14 NB is extension of Poisson distribution Better suited than Poisson to model crash data Poisson appropriate when mean = variance Crash data - variance typically > mean i.e. overdispersed
Background image of page 14
Image of page 15
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 10/26/2011 for the course ECON 101 taught by Professor Dr.siam during the Spring '11 term at American University of Kuwait.

Page1 / 47

9_27_11_HSM_SPF_CMF - Crash Prediction, How? You are tasked...

This preview shows document pages 1 - 15. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online