Public Transport and Railways

ETHZ / Bauingenieur Bsc. / 5.Semester / HS2020 / Public Transport and Railways

ETHZ / Bauingenieur Bsc. / 5.Semester / HS2020 / Public Transport and Railways


Set of flashcards Details

Flashcards 94
Students 48
Language Deutsch
Category Traffic
Level University
Created / Updated 02.10.2020 / 28.01.2025
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Crew Scheduling

Crew scheduling is typically a sub-problem completed for each "Base":

1. Develop rough plan based on vehicle circulation for a given period (e.g. 1-week)

2. Assign generic workers to vehicles based on crew working criteria.

Crew Working Criteria - because CREW are PEOPLE!

  • Maximum working/driving hours, rest time, meal breaks, rest relief
  • People cannot sleep anywhere: daily schedule must return crew to starting base
  • Employee fairness: distribute unattractive services (holidays, boring, "unsafe")

Simple Timetable Planning - Assumptions

Simple methods can be used to plan timetables for many bus systems and small railways.

Assumptions:

  • Vehicles do not interact with each other or interactions can be summarized in minimum headways
  • Service is focused on lines: network is not planned or optimized

Bus Bunching

Solutions:

  • Prevent buses from becoming late (e.g. public transport priority, buffer times)
  • Real-time headway management (e.g. second bus waits at time point to maintain headway)

Required amount of vehicles

\(N = \frac{\text{min. circulation time}}{\text{headway}}\)

min. circulation time including headway, dwelling, stops etc.

N --> rounding up to next integer

Train-Track Interaction

Network Dilemmas

- node density (spatial accessibility)

- network density

- line density

- frequency

- number of services / systems

- connection structure

- budget

Network Functions - Hierarchies

A - Passing (long distance)

B - Connecting (long-distance/regional transport)

C - Collecting (regional transport)

D - Accessing (urban or local transport)

Spatial Scope - Three area types for planning

Core focus area

Large focus area

Assessment area

Spatial Analysis

Main spatial characteristics relevant for planning:

  • Quantities of residents and work/education places
  • Spatial structure of land uses and focus points

Basic information required includes:

  • Population number of municipalities, neighborhoods
  • Workplace number of municipalities, neighborhoods
  • Population and work/education place densities on a hectare basis

Spatial Structures - Types

Demand Analysis

Indicators:

  • Line loads per section, per route
  • Origin Destination matrices with ideal lines
  • Stop level passenger numbers
  • Temporal regularities, phenomena, trends
  • Trip purposes

Data sources:

  • Passenger counts by cross section between stops
  • Boarding/alighting passenger counts per stops
  • Systematic surveys by train personnel
  • Transport models
  • Statistic agencies, surveys
  • Annual reports of transport companies

Production Analysis

Important parameters:

  • Average utilization of trains or buses ("Load Factor")
  • Average number of passengers per unit    [Pkm/train km]
  • Average mileage of the rolling stock per year    [km/train] [km/bus]
  • Number of train or bus kilometers per employee unit    [Train-km/employee]

Demand Distribution

Demand is not only different over time, it is also directional.

Stop Spacing

Standardized or Differentiated

differentiated --> demand oriented service

standardized --> systematic and standardized service

Tradeoffs:

  1. Accesibility --> depends
  2. Availability --> depends
  3. Frequency --> standardized
  4. Transport speed --> differentiated
  5. Need to transfer --> standarized
  6. Comfort --> differentiated
  7. Reliability --> differentiated
  8. Convenience --> differentiated

Degrees of systematization for timetabling

Level 0 - Demand oriented timetable

Level 1 - Periodic timetable

Level 2 - Symmetric periodic timetable

Level 3 - Integrated periodic timetable (IPT)

Level 4 - Deconstructed hub IPT

Line Types

Through Lines Disadvantages

Infrastructure oftentimes does not permit such lines

There are not always two corridors on opposite sides of a central area that generate similar demand.
--> asymetric demand, utilization is low on weak leg

Ring Lines

Multiple tangential line connected to each other give rise to ring lines, going around the entire city center.

good in  (S1) Dense self-contained areas --> e.g. Berlin

True ring lines:

  • Vehicles move all along the same direction and do not have a large buffer time anywhere
  • Attractive for passengers, difficult to manage

False ring lines:

  • The ring lines are divided operatively in at least one place (which works as end-station)
  • Passengers see a supply cutoff at this point, but operation is more stable

Methods for integrating lines into systems

Reduction method:

  1. Start from maximum network of all routes which are basically accessible.
  2. Determine construction, operating costs, travel-time costs for each section.
  3. Iteratively remove most expensive sections --> transferring demand to the remaining network.
  4. The procedure ends when a predefined number of lines is reached.

Traveling sums:

  1. Starting from the maximum traffic network
  2. For each pair of stops, the best route between them is determined
  3. The loading of these best routes forms the basis for the line formation.

Progressive methods:

  • Target figure: Minimize the total running time and maximize share of transfer-free trips
  • Network building begins with the selection of a cross-section
  • Iteratively, route sections are added, based on the gien target figures

Traffic flow method:

  • Doesn't focus on edges, but on nodes
  • Sections are joined, depending on the traffic flows in these nodes
  • a maximum line length is given
  • the process strives to find routes with the shortest travel times and minimum transfers

Increasing capacity in peak hours

Long distance transport:

  • Avoid extra supply, extra capacity comes from larger vehicles
  • Once demand has reached a sufficient level, the supply can be increased integrally at system level

Regional railways with pronounced demand peaks:

  • Increase of service capacity, by systematized or non systematized extra services
  • Usually off peak demand not sufficient to justify entire service period timetable frequency increase

S-Bahn:

  • typically, reinforcement lines, plus non systematized services, and increased frequency
  • Increasing non systematized services + sustained demand growth leads to reinforcing lines

Bus:

  • typically reducing headways
  • Previously integral increase of system frequency was also common, in the form of reinforcement lines, now less
  • Adjustment of the vehicle capacity by longer buses

Decreasing capacity in off-peak hours

- Decrease of service frequency

- Increasing the headways while maintaining the entire network

- Adjusting product levels by eliminating a product lebel

- Change of transport mode from train or tram to bus

- Adjustment of the vehicle capacity by shortening trains or smaller buses

Public Transport - Cost, revenue, cost recovery

Cost:

  • Variable Cost  (Track Access, Fuel, Electricity, Maintenance, Operation, Labour)
  • Fixed Cost  (e.g. Depreciation, Interest)

Revenues

  • Fares
  • Subsidies
  • Advertisements
  • rent (if an operator owns attractive property)

Full cost recovery is rare (e.g. ZVV 70%) but PT has societal benefit tasks

Train and Bus Lifetimes

Bus: 10-12 years

Trains: up to 40 years

Different Fare Systems

Infrastructure - 3 Level Models

Level 1 - traffic

Level 2 - control

Level 3 - building & maintenance

Infrastructure - Capacity Improvements

Capacities can only be expanded in leaps and bounds.
--> as a result, infrastructures are underutilized on average

Capacity expansion always causes jump costs, which are incurred immediately.
The additional income comes only later. Capacity expansion is therefore a high economic risk.

Capacity expansion can lead to very complex and expensive linkage strutures and nodal areas.

Track Transport

Trackless:

  • the track/lane can be freely selected by the driver
  • keeping direction based on friction --> roadway must have high friction
  • no technical guarantee that the vehicle is following the track/lane

Track-based:

  • the vehicle is forced on the track/lane

Why Railways?

- Mono-dimensional along one line only --> no possibility to deviate

- Bi-dimensional means very precisely on that line, horizontal gaps to other objects is controllable and very small

- Three-dimensional movement means going up and down is not easy, adherence problems and adhesion challenges

Train on Track - geometric/static/dynamic interactions

Railway Track - Distribution of weights

Railway - Movement of the Wheels

Railways - Curves

Centrifugal acceleration leads to:

  • reduction of passenger comfort
  • possibly derailment
  • track-, vehicle wear

Rails at an angle in curve  (cant) --> to compensate lateral acceleration

Cant deficiency/excess --> lateral acceleration not compensated leads to the things above

Tilting body --> Maximum speed can be increased by 30% on same infrastructure

  • conventional: car body suspension is between wheels and body
  • passive car body inclination: suspension is above (car body is suspended)

Active tilting trains --> sensing curves, and activating tilting mechanisms

Transition curves: smooth transition between straight and curve (reduces risk of derailment)

Rails - Foundation

Ballast / Ballastless Tracks

Ballast tracks:

  • + the gravel superstructure is inexpensive to build
  • + advantageous design in bad underground
  • + easy to rebuild
  • + insensitive to derailment
  • + provides noise (and vibration) dampening
  • - depending on the line load, the ballast must be cleaned and partially repaced
  • - in high-speed traffic, the secondary deflection may cause the rails to be corrugated --> sound increase 10dB

Ballastless track:

  • + long-term stable track position
    • long bridges
    • tunnels (firm ground and vertical space limited)
  • + Low (or none) maintenance costs for small maintenance (unknown costs for big repairs, replacements
  • + no gravel flight or movement
  • - track position poorly regulated
  • - louder due to higher sound reflection
  • - difficult item replacement
  • - more complex electrical insulation
  • - expensive (often 2 to 2.5 times more expensive)

 Train Vehicle Profile - Transversal

Train Vehicle Profile - Longitudinal

Energy Collection

ERTMS

European Rail Traffic Management System

ERTMS Level 1 and 2 --> fixed block

ERTMS Level 3 --> moving block

Interaction of Vehicles

Following

Opposite

Merging

Sequence

Crossing