Verkehr III

1430 ms

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

• Passenger cars
• Buses
• Trucks
• Recreational vehicles

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

Its

• weight
• dimensions
• operating characteristics

are used to establish the design standards

• Straight
• Horizontal curve
• Transition curve (Übergangskurve)

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

• 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

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

• Straight
• Vertical curves
  • Crest curves
  • Sag curves

• 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

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

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

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

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

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

• 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

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)

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

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

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

performance is defined as serviceability or reliability of the infrastructure

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

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:

• 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:

• 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:

• 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