1. Vehicle Motion Human Factors

2. Homework
Chapter 2: #3, 6, 7

3. Human Factors Rational Design of goods and services for people
Primary human requirements
increased speed
increased range
increased capacity
Secondary
safety, comfort & convenience, status

4. Environment Where workspace is located
effects person’s performance
lighting, noise, vibration, climate, pollutants
Man - Machine - Environment interaction
want to optimize

5. Human Variation Design is based on 90% of people
Top and bottom 5% not in design
who’s not included?
Adaptation & Instruction
want to limit instructions
How is a car laid out?
Where are the important components
Commonality

6. Human Contact Physical, Physiological, Biochemical
Size
Reach
Strength
Body Composition
Perception - Reaction
P-R, Info Processing, Motor Performance
Cognitive and Social

8. Pedestrians Important piece of urban design Crosswalk placement
Social distance
Personal distance
Intimate distance

9. Pedestrians How does personal space change ? Transit airplanes
waiting areas
cars

10. How big is a pedestrian?

11. Visual Acuity Contrast, brightness, illumination, relative motion
Acuity decreases with increased visual angle

12. Perception Reaction Time
Time from stimulus to response
Depends on complexity of info
P-R seconds depending on event type
Wake Up

13. Fig 2.2 pg 22 P-R times Expectancy
Continuity – experiences of the immediate past are expected to continue
Event – Events that have not happened previously will not happen
Temporal – for cyclic events the longer a given state is observed the more likely it will change

14. Distance covered during P-R time Pedestrians
1.47Vt
Pedestrians
~ 3.5fps, elderly pop ~3.0 fps just changed
Table 2.3
DWI - Figure 2.3

15. Lateral Displacement
Driver moves away from objects on the side of the road
Want to maintain a comfort zone between car and objects

16. Lateral Displacement
Closer objects is to pavement edge the more lateral displacement
3.3 ft for 8 ft lane
1.8 ft for 12 ft lane
Can estimate lateral displacement
need l, v, dQ/dt

17. Lateral Displacement Critical rate of change in visual angle
if dQ/dt is less than critical assume collision
l = a cotQ
dl/dt = -acsc^2QdQ/dt
dQ/dt = va/(a^2+l^2)

18. Lateral Displacement
A vehicle traveling 40 mph was observed to displace laterally when it was 300 feet from a bridge abutment placed 6 feet to the right of the path. At what longitudinal distance from the same abutment would you expect the same driver to displace laterally when traveling 60 mph?

19. Lateral Displacement What is critical rate of change (dQ/dt)
dQ/dt = {(40*1.47)*6}/(6^ ^2) = rad/sec
For 60mph
= {(60*1.47)*6}/(6^2 + L^2)
L = 368 feet

20. Forces Acting on a Vehicle
Propulsive (M)
Resistance (R)
Centrifugal (C)
Weight (T) ma
Supporting Forces (S)

21. Resistance Inherent Grade Curvature
vehicle is moving through something
R is a function of T and V
Grade
adds resistance or increases speed
Curvature
from centrifugal force
can be eliminated w/ banked curves

22. Grade

23. Curvature

24. Vehicle Motion
Superelevation e is the amount of banking in ft/ft on a curve
e + f = v2/gr depends on speed
Table 2.4 – Values for f
to negate f (no hands) e = v2/gr v in fps
e= v2 /15R v in mph

25. Vehicle Motion v=dx/dt a = dv/dt a=(dv/dx)v vdv = adx v =at + v0
x = v0t +1/2(at2)

26. Braking Distance Db= (v2-v02)/2g(f+G)
f = 11.2fps^2/32.2 = used for design
Not Brake type dependent – why?
NOT Weight dependent - why?
Does not account for reaction time

27. Safe Stopping Distance
Time to perceive and respond + time to brake to a stop
P-R time =2.5s want to be conservative
SSD = 1.47V(2.5) + (v2-v02)/2g(f+G)

28. Decision Sight Distance
Time to perceive and respond + time to brake to a stop
P-R time =2.5s want to be conservative
SSD = 1.47V(decision time) + (v2-v02)/2g(f+G)

29. Example How long does it take a vehicle to brake to a stop from 60 mph
On a 5% downgrade
On a 5% up grade
On ice on a 5% upgrade

30. Dilemma Zones
Area around intersection - can’t stop can’t go –occurs when Yellow time is too short
Need proper Y
P-R time

31. Dilemma Zones a2 is comfortable deceleration rate
4- 5 fps standing
8 -10 fps seated
xo > xc no problem
xo <= xc dilemma
Cannot cross intersection in Y+AR

32. Dilemma Zones Can find minimum amber needed to eliminate dilemma zone
Amber should be not more than 5 seconds
Amber time = D/1.47V
Assume 1s P-R time for signal

33. Dilemma Zones How long should the amber interval be for the following:
Design Speed = 35mph
Intersection = 30 feet wide
Vehicle length = 15 feet
P-R time = 1 s
Stopping distance = 1.47*35*1 + (35^2-0^2)/[30(0.0348)] = 169 feet
Amber = 169/(1.47*35) = 3.28s

34. Dilemma Zones How long should the amber interval be for the following:
Design Speed = 35mph
Intersection = 30 feet wide
Vehicle length = 15 feet
P-R time = 1 s
Distance thru intersection= = 213 ft
Amber = 213/(1.47*35) = 4.13s can use 3.28s Y + 1s AR