1. The safety problem: nature of the problem, extent (partially covered already), factors
CE 552 week 4

2. Hauer Philosophy
You can learn the effect of a safety treatment with before and after observation – wrong
You have to have true randomized experiments to learn anything – wrong
You can learn from experience – ok
You must take great care in doing so – ok
You shouldn’t experiment – wrong
“the only way to find out what will happen when a complex system is disturbed is to disturb the system, not merely to observe it passively” – Box 1966

3. Hauer Philosophy Opportunities abound
If we do evaluate, we do so “in-house” because there is risk of failure
We do not publish because the measure failed
What is needed …
Sound methodologies
Collective will to employ them properly

4. Hauer quotes
“Perhaps we transportation engineers can not act in good faith as the custodian of traffic safety because the goal of safety and efficiency are too often in conflict”
“Within limits, highway traffic engineers can make roads safer or less safe so we must know the safety repercussions of our choices”

5. Road Safety Defined (From a Science-based Perspective)
Improved “security” may decrease “safety”
Accident or crash?
Is safety the number of crashes per time? What if some days have no crashes – perfectly safe?
Use running average?
Use longer period of time?
Safety may change – must be allowed to
Requires use of statistics (expected values) and reliability during a specific period
Counts are a “hint” at the underlying numbers

6. Federal Transportation Goals
Safety
Old: reduce fatality rate to 1.0
New: ???
Congestion
Preservation
Environment

7. Effect of Crashes on Traffic Congestion and Travel Reliability
Notes: Cambridge Systematics study shows that the costs of traffic crashes is nearly two and half times the cost of congestion – $164.2 billion for traffic crashes and $67.6 billion for congestion

8. Economic cost of crashes
value of life (FHWA Iowa division memo): $5.8million?
Iowa uses:
“You'll see that we've sold out...errrrrr...begun to use the Federal numbers in our B/C analyses for TSIP (and probably other things).” MDP
“For SICL, DOT uses 200, 100, 10, 1 and not actual $$$.  PDO for SICL is included via frequency and rate so thus no need to replicate via severity index.” MDP

9. Evans’ thoughts
“Factors” rather than “cause” (contributing circumstances)
Is it safer to keep a pet crocodile than a pet dog? – how to answer this?

12. Human Factors Driver intelligence/skill ladder in car
Des Moines drivers
Reaction time tests
Distractions
docs\text_messaging_crash.mht
Distracting Miss Daisy (includes risk compensation)
Cell phone bill; KCCI report
Speeding
Why the EZ pass speed is 15 mph
Fricker p. 307 “think about it”

13. NCHRP 500
aggressive driving
unlicensed drivers
seat belts
Drowsy/distracted
Alcohol

14. Road Crash Factors