Verkehr I
Norman Garrick
Norman Garrick
Fichier Détails
Cartes-fiches | 57 |
---|---|
Langue | English |
Catégorie | Code de la route |
Niveau | Université |
Crée / Actualisé | 03.08.2021 / 14.08.2021 |
Lien de web |
https://card2brain.ch/box/20210803_verkehr_i
|
Intégrer |
<iframe src="https://card2brain.ch/box/20210803_verkehr_i/embed" width="780" height="150" scrolling="no" frameborder="0"></iframe>
|
Definition: Access, Accessibility
Ability/opportunities to reach the desired destination
is defined through:
- Generalised cost: Travel Time, Cost, Comfort
- Proximity of bus station
Goal of Transportation Planning: maximize Accessibility
=> for higher productivity & more user for public transport
Definition: Impendance function
describes difficulty to reach a destination
Definition:
- User Equilibrium
- System Equilibrium
System Equilibrium
- minimal total generalised cost
=> additional car makes other cars slower
User Equilibrium:
- shortest route for all users
=> used routes have same generalised cost
=> not used ones have higher cost - illustrated through Minimum Tree
Time Mean Speed
Space Mean Speed
TMS
- measured with radar scanner
- = arithmethic average of spot speed:\(u_t =\frac{\sum v_i}{n}\)
SMS
- areal photograph
- total distance/total time
- harmonic mean: \(u_s =\frac{n}{\sum{1/v_i}} \)
Draw the traffic flow curves
- u-k
- u-q
- k-q
-> siehe Notion
Definition: directional distribution
- factors, affects on design
- Solution
Difference of traffic flow in two opposite direction
- Travel flow during peak hours is mainly focused in one direction
=> generated through insufficient land use mix - problem: empty streets & pt in other direction => insufficient use of infrastructure
Solution
- mixed land use
- reversible lande
- zipper machine
Solution to reduce temporal variation of traffic flow
- mixed land use
- differential pricing: higher charge of transport systems during rush hour
=> ppl who are not dependent on traffic during peak hours delay their travel
Characteristics of Travel Flow
- temporal variations: traffic flow depends on observation time & space, peak hours,
- spatial variation:
- Travel flow depends on local land use (city: higher q)
- depends on the infrastructure provided (street width)
- depending on travel direction
- change of transportation & land use changes travel flow as well
How is traffic data being collected?
- permanent & temporary count stations
- GPS data
Definiton: ADT
How is ADT being collected
Why is ADT alone not sufficient for traffic planning
?
Charactersistics of Capacity
Capacity of a street is not fixed but based on level on level of congestion we are willing to put up with
=> determined by a desirable Level of Service
-> based on Social, Economic, and Tracel Capacity
=> is a political number
- characterized by DHSV: Design hourly service Volume
Definition: Design Hour Volume DHV
- issues of DHV
- how to select DHV
for traffic planning we need to set a future time we want to plan/design for
- DHV describes traffic occurence in the design hour & year and in the design direction for the design capacity (based on Level of Service)
- estimated from ADT
How to select DHV:
- traffic planning for the traffic occurence of 50th-200th most busy hour of the year
Problems:
- Determining DHV is a Trade off between too many congestion hours & inefficiently big facility
- When Design year >20 y in the future: predict & provide
Definition "predict and provide" Approach
- problematics
- Traffic design solely based on past trends & numerial datas
- doesn't take into account societal parameters, like change of mindset, that can influence traffic occurence
Problems
- reacting instead of acting
- Induced Traffic:
- wider streets -> attracts more cars -> bigger traffic occurence than predicted -> again wider streets
- unpredictable occurence -> more traffic in comming year -> again predict & provide -> massive & insufficiently used infrastructure
- wrong assumptions
- new technologies
Definition: Level of Service
- Problematics of low LOS
= What level of traffic concentration do we want to have for design hour?
low LOS:
disigning a low LOS during busiest hour of the year => broad streets
=> Empty & insufficiently used street for the rest of the time
Calculation: Number of Lanes
Nr. of Lanes = DHV/DHSV
- DHSV: given by LOS
- DHV = ADT * Directional Split * Traffic in Designhour (as fraction of ADT)
5 Levels of Autonomous Driving
- driver assistance
- partial automation
- conditional automation
- high automation
- full automation
Evolution of the Urban Form (through Transportation)
- before cars: compact cities that were designed for walking
- cars & electric rail changed shape & size of city
- faster travel BUT not reduction in total travel time (-> 30-minute commute principle)