Operational Effects of Geometric Design

Question 1

What is the basis for classifying the highway and street network?

Answer 1

Land access and mobility

Question 2

Road classifications

Answer 2

1. Principal Arterial
2. Minor Arterial
3. Major Collector
4. Minor Collector
5. Local Road

Question 3

Context Sensitive Design

Answer 3

Create projects that function safely and efficiently and are pleasing to users and neighboring community

Question 4

Access Control

Answer 4

legal limitation or restriction of access to and from properties neighboring highway facilities

Question 5

A person’s ability to recognize and respond to a situation that may require a decision and action

Answer 5

perception-reaction time

Question 6

What PRT is used for calculating stopping sight distance?

Answer 6

2.5 seconds

Question 7

Vulnerable Road User

Answer 7

a road user unprotected by an outside shield

includes pedestrians, bicyclists, person operating a personal mobility device, motorcyclists, etc.

Question 8

Design speed

Answer 8

selected speed used to determine various geometric design features of the roadway

Question 9

High and low speed design threshold

Answer 9

high-speed: 50 mph or greater
low-speed: 45 mph or less

Question 10

Driver eye height

Answer 10

3.5 feet

Question 11

Target height (SSD)

Answer 11

2 feet

Question 12

Target height (PSD)

Answer 12

3.5 feet, represents upper portion of opposing car

Question 13

L=KA

Answer 13

L = length of vertical curve (ft or m)
K = horizontal distance to affect one percent change in grade
A = absolute value of algebraic difference in grades (percent)

Question 14

What criteria are used to establish length of sag vertical curves?

Answer 14

headlight sight distance
passenger comfort
drainage control
general appearance

Question 15

Headlight height (sight distance for sag vertical curve)

Answer 15

2.0 feet

Question 16

What is the desired clear zone for a high-speed, high functional class roadway with level roadside slopes and tangent alignment?

Answer 16

30 feet

Question 17

Recoverable slope

Answer 17

1V:4H or flatter
1V:6H preferred on high speed roads

Question 18

Non-recoverable slope

Answer 18

1V:4H to 1V:3H

Question 19

Critical slope

Answer 19

Steeper than 1V:3H, may result in overturning

Question 20

System interchange

Answer 20

Connects two controlled-access highways or freeways, no at-grade intersections at ramp terminals

Question 21

Service interchange

Answer 21

Connect a higher functional class roadway to a lower functional class roadway, may have at-grade intersections at ramp terminals

Question 22

Criteria for choosing between and interchange or an at-grade intersection

Answer 22

• design designation
• reduction of bottlenecks or spot congestion
• improve safety
• site topography
• road-user benefits
• traffic volume warrant