Design Philosophy

Question 1

what are the 5 characteristics of a safe road

Answer 1

consistent
transitions
controlled release of info
repeated info
forgiveness

Question 2

Design domain can be

thought of as?

Answer 2

a range of values that a design parameter (e.g. coefficient of deceleration,
lane width) might take. These values should be justified in an engineering sense (e.g.
based on test data, sound reasoning, etc) and therefore have a reasonable level of
defence if questioned

Question 3

what is the operating speed

Answer 3

it is the 85th percentile speed of free speeds of users (not obstructed by other cars)

Question 4

what is the desired speed

Answer 4

The speed driven at on a long, level tangent when not constrained by other vehicles (depends on drivers perception)

Question 5

what is the speed environment

Answer 5

assumed value relating to a length of road incorporating several curves . is the 85 percentile value of the desired speed for that length.

Question 6

what is the design speed

Answer 6

speed chosen based on horizontal/vertical and cross section changes. should not be lower than 85 percentile of operating speed .

Question 7

what are the four steps in alignment design method

Answer 7

1 estimate speed environment
2 estimate design speed
3 assess speed environmetn
4 if speed environment not as estimated, revise

Question 8

what is general driver behaviour in regards to speed and curves

Answer 8

will adjust for horizontal curves

will maintain desired speed on grades

Question 9

how much should the speed vary by and whats the expected speed for the following environments?
-high speed
intermediate
low speed

Answer 9

high speed 100-130 vary

Question 10

if there is an isolated design feature such as roundabout what must you do to its approach

Answer 10

reduce desgin speed in series of steps or reducing radius curve