ETHZ


Kartei Details

Karten 38
Sprache Deutsch
Kategorie Verkehrskunde
Stufe Universität
Erstellt / Aktualisiert 04.01.2017 / 23.01.2018
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What percentage of Swiss households had at least one private car in 2005?

International comparison between swiss and american networks

Traffic networks consist of

Name four human factors which affect driver characteristics

  • Vision or visual reception
  • Hearing perception
  • Magnitudes
  • Quickness

How is the reaction to a stimulus divided?

PIEV - perception-reaction process

  • Perception
  • Interpretation
  • Emotion-Decision
  • Volition-Reaction

  • What are PIEV times used for?
  • What are the typical PIEV times determined from research?

  • Sight distances
  • Safe approach speeds at intersections and interchanges
  • Timing of signals at railroad crossing
  • Traffic signal change intervals

0.5 to 0.75 seconds for most driving tasks up to 4.0 seconds for complex driving tasks

What's the reaction time to break

1430 ms

What are the requirements for the power of a vehicle? What resistance does it have to overcome?

  • Air resistance
  • Rolling resistance
  • Curve resistance
  • Grade resistance

What are the general vehicle classes?

  • Passenger cars
  • Buses
  • Trucks
  • Recreational vehicles

How is a facility designed?

The largest vehicle to use the facility with considerable frequency is used.

Its

  • weight
  • dimensions
  • operating characteristics

are used to establish the design standards

Elements of horizontal alignment

  • Straight
  • Horizontal curve
  • Transition curve (Übergangskurve)

Simple horizontal curve

Compound horizontal curve

What's typical for transition curves

  • placed between tangents (or straights) and horizontal curves
  • gradual increase or decrease in radial forces
  • typically spiral in shape

What are the general design recommnedations for horizontal alignment

  • flowing line that generally conforms to natural contours in preferable
  • minimize use of short curves
  • long tangents needed on two-lane highways to provide passing sight distance
  • avoid compound curves
  • avoid abrupt reversals in alignment

What are the main criteria for the vertical alignment

  • adequate stopping sight distance
  • proper drainage
  • comfort
  • appearance

Elements of vertical alignment

  • Straight
  • Vertical curves
    • Crest curves
    • Sag curves

What are the general design recommendations for vertical alignment

  • Use smooth grade lines with gradual changes
  • Avoid "roller-coaster" or "hidden-dip" profiles
  • On long grades, place steepest grades at bottom and flatten near top of grade

Vertical curve

Types of nodes

  • Intersections
  • Roundabouts (traffic circles)
  • Intersection-free nodes

Critical gap

The critical gap is the minimum average gap length that will be accepted by drivers

A way to determine critical gap:

number of accepted gaps shorter than critical gap = number of rejected gaps longer than critical gaps

Advantages and disadvantages on roundabouts

The majority of road traffic injuries affect mostly whom?

people in low-income and middle-income countries - 90% of road traffic deaths occur in low-income and middle-income countries

What can be said about the number of deaths compared to the degree of motorization in a country

As the degree of motorization increases, there is a decrease in the number of deaths per registered vehicle

commonly used crash rate indicators and what they are good for

possible countermeasures so crashes are avoided

  • red light cameras for intersection crashes
  • rumble strips on highways
  • street lights at night

important points to consider to correctly evaluate the effectiveness of a countermeasure

  • need crash data from before the implementation and after the implementation
  • need crash data from a control location (crash rates can change for many reasons)
  • need to measure effects long enough after the implementation to avoid the novelty effect

typical applications of:

  • flexible pavement 
  • rigid pavement

Flexible pavement:

  • traffic lanes
  • auxiliary lanes
  • ramps
  • parking areas
  • frontage roads
  • shoulders

Rigid pavement

  • high volume traffic lanes
  • freeway to freeway connections
  • exit ramps with heavy traffic
  • under overpass which needs clearance
  • slow, and stop-go traffic (bus station, intersection)

Advantages and disadvantages to flexible pavement

advantage:

  • adjusts to limited differential settlement
  • easily repaired
  • additional thickness added any time
  • non-skid properties do not deteriorate
  • quieter and smoother
  • allow for a greater temperature variation

disadvantage

  • loses some flexibility and cohesion with time
  • needs resurfacing sooner than rigid concrete
  • not normally chosen where water is expected

Advantages and disadvantages to rigid pavement

advantage:

  • good durability
  • long service life
  • can withstand repeated flooding and subsurface water without deterioration

disadvantage:

  • may lose non skid surface with time
  • needs even subgrade with uniform settling
  • may fault at transverse joints
  • requires frequent joint maintenance

conditions of pavement surface in terms of its general appearance

pavement distress with:

  • flexible pavement
  • rigid pavement

flexible pavement:

  • fatigue cracking
  • rutting
  • thermal cracking
  • other mechanisms, asphalt concrete mix distresses

rigid pavement:

  • tensile stresses crack concrete slabs
  • environment-related mechanisms causing tensile stresses
  • load related mechanisms
  • environment and load stresses are additive

What is performance?

performance is defined as serviceability or reliability of the infrastructure

types of rehabilitation

  • maintenance - patching or sealing cracks
  • repair - adding a layer of asphalt overlay
  • reconstruction - tearing down the existing infrastructure and building a new one

types of measurements

traffic measurements:

  • cross-section measurements (flows) [traffic volume per time]
  • directional flows in a small scale [traffic flow per time]
  • directional flows in a large scale [traffic flow per time]

surveys:

  • surveys

measurements in stationary traffic:

  • counts [parking offers, parking time, trip purpose, occupancy rate]
  • survey

pros and cons of fixed sensors

pros:

  • high experience, high potential and quality
  • mature technologies
  • accurate traffic flow and speed
  • no car positioning error

cons:

  • expensive to install and mantain
  • limited coverage
  • low travel time accuracy
  • low precision for urban areas
  • can be affected by bad weather conditions

pros and cons of FCD (cellular phones)

pros:

  • large coverage area
  • low costs compared to conventional systems
  • high quality data
  • well suited to urban areas
  • integration of data with existing sources
  • easy to implement
  • not affected by adverse weather

cons:

  • sophisticated processing data
  • cost of communication
  • arrangements between actors are necessary
  • R&D efforts still required
  • privacy concerns

pros and cons of naturalistic driving data

pros:

  • large amounts of data, including hard to get information
  • high quality / accurate individual vehicle data
  • not affected by weather conditions
  • large coverage, well suited to urban areas

cons:

  • very expensive to install and maintain
  • limited number of test vehicles
  • non-mature technology, low experience
  • R&D efforts still required