Theme 4 Flexible capacity operations

transcript

Future of BRT: Flexible Capacity Operations

Juan Carlos Muñoz Bus Rapid Transit Centre of Excellence

Pontificia Universidad Católica de Chile

September 20, 2013

Motivation: Efficiency in the use of road space

www.BRT.cl

What can we say about bus service?

Bus is critical to provide a good door-to-door transit alternative

for many journeys:

• Much higher network density and coverage than rail

• Greater flexibility in network structure

• Low marginal cost for service expansion

BUT as traditionally operated, it also has serious limitations:

• Low-speed

• Subject to traffic congestion

• Unreliable

• Harder to convey network to the public

• Negative public image

What can we say about the user?

• Perceives waiting time and walking time twice as important as

travel time inside the vehicle.

• Avoids transferring, specially if they are uncomfortable

• Needs a reliable experience

• Requests a minimum comfort experience

• Requests information

• Needs to feel safe and secure

What can we say about the bottlenecks?

Capacity per lane:

• “Only a fool breaks the two second rule” => 1,800 veq/hr-lane

• 1 Bus ≈ 2 veq => 900 buses/hr-lane

Capacity per lane at junctions:

• 40 – 60 % of lane capacity => 450 buses/hr-lane

Capacity at Bus Stops:

• Depends on the amount of passengers boarding and alighting

• ≈ 20 - 40 sec. per bay => 180 – 90 buses/hr-bay

Buses are involved in this vicious cycle

Operation cost grows

Income and Population grows

More cars in the city

Bus Demand drops

Car becomes more attractive

Bus frequency drops Buses cover fewer miles per day

Bus fare increases

And we need to make buses attractive to car drivers…

More congestion

And delays

However, this doesn’t affect Metro as

Can we provide Metro-like service with buses?

• Fast

• Low wait time

• Comfortable

• Reliable

• Good information

• Branding

Transit Leaders Roundtable MIT, June 2011

• Fast

• Low wait time

• Comfortable

• Reliable

• Good information

• Branding

Yes we can … We still believe

(several pieces are already there in cities worldwide)

The good news are:

COURAGE WILL BE REWARDED

IMPROVED EFFICIENCY

IMPROVED SERVICE QUALITY

Reduced bus costs •Less buses required

•Lower cost per km

Improved bus productivity •More pax/bus-day

Attracts more passegers

Improves revenue

IMPROVED FINANCIAL VIABILITY

Better buses More investment into new buses & cleaner

technology

Lower Subsidies

Reduced private car use & traffic congestion

Improved energy efficiency

Reduced emissions

Operational benefits •Shorter cycle time

•Reliable operations

•Higher productivity

Increase Bus speed, Frequency, Capacity and Reliability Passenger

benefits •Reduced travel time

•Reduced waiting

•Higher comfort

•Reliability

Source: Frits Olyslagers, May 2011

Fast Reliable

Metro Attributes

Actions

Comfort Low waits

Main drivers

Increase

Regular

Headways

Increase

Capacity

Increase

Frequency

•Segregated ways/lanes

Segregated ways/lanes

Low Flow: Intermittent Bus Lanes

Medium Flow: Bus-Only lanes

High Flow and Limited Capacity: Only bus street

J. M. Viegas

Low Flow: Intermittent Bus Lane (IBL)

Demonstration in Lisbon Implementation: Technical Components

Installation of the Loop Detectors IBL local controller

Static signalization

(advance notice)

Variable message

longitudinal LEDs

Vertical variable message

signal

Ricardo Giesen ©

Without IBL vs. with IBL (51 sec)

Demonstration

Only Bus Lanes

BUS ONLY

Setback!

R. Fernández

Partial closure of streets for cars, but not for buses

Closed Junction (Brussels) Closed lane (Zurich)

P. Furth

Fast Reliable

Metro Attributes

Actions

Comfort

Increase

Regular

Headways Main drivers

Increase

Capacity

Increase

Frequency

•Segregated ways/lanes •Reduce dwell times

•Fare payment off-bus •Buses with multiple doors

Low waits

Guayaquil, Ecuador

Level bording in Quito, Ecuador

Guayaquil, Ecuador

TransMilenio, Bogota, Colombia

TransMilenio

Istanbul BRT

Divided Bus Stops

Bus only street?

Weaving distance: 3-4 bus

R. Fernández

Platform 2 Platform 1

Stop area 2 Stop area 1

Divided bus stop

Divided rail station

Platform 2

Platform 1

R. Fernández

Divided Bus Stops

Fast Reliable

Metro Attributes

Actions

Comfort

Increase

Regular

Increase

Capacity

Increase

Frequency

•Increase distance between stations

Low waits

Fast Reliable

Metro Attributes

Actions

Comfort Low waits

Increase

Regular

Increase

Capacity

Increase

Frequency

•Increase distance between stations •Express services

Choosing the Right Express Services for a Bus Corridor with Capacity

Constraints

Homero Larrain, Ricardo Giesen and

Juan Carlos Muñoz

Department of Transport Engineering and Logistics Pontificia Universidad Católica de Chile

Introduction

Operación “Carretera” Operación Expresa

Higher in-vehicle travel time Lower in-vehicle travel time

No transfers May force some transfers

Higher operation costs, in terms of $/Km

Lower operation costs, in terms of $/Km

Other aspects: capacity, comfort, accessibility, etc.

Limited stop services All stop services

*Jointly operated with all stop services, assuming a constant fleet size.

Objective

• Formulate a model that allows to choose which combination of services to provide on a corridor, and their optimal frequencies.

• Determine opportunities for express services (or limited stop) on a corridor based on its demand characteristics.

The Problem

p1 p2 pi pn … …

The Problem

• Different operation schemes.

p1 p2 pi pn … …

… … l1, f1

… … l2, f2

… … l3, f3

… … l4, f4

The goal is to find which services to offer, and their optimal frequencies.

li: Line i fi: frequency of line i

The Model

• The goal of this model is to find the set of services that minimize social costs:

– Operator costs: will depend on what services are provided, and their frequencies.

– User costs:

• In-vehicle travel time.

• Wait time.

• Transfers.

The Model: Assumptions

• Given transit corridor, with a given set of stops.

• Fares are constant for a full trip.

• Number of trips between stops is known for a certain time frame.

• Random arrival of passengers at constant average rate.

• Passengers minimize their expected travel times.

The Experiment

• Steps:

– Defining network topology.

– Defining demand profiles. • Load profile shape.

• Demand scale.

• Demand unbalance.

• Average trip length.

– Build scenarios and construct an O/D matrix for each one.

– Optimize scenarios defining the optimal set of lines for each one.

Express Services: Main Conclusions

• Allow increasing the capacity of the system

• Significantly reduces social costs

• Few services bring most of the benefits

• Limited stop services are more promising in these situations:

– The longer the average trip length

– High demand

– High stop density

– Demand is mostly concentrated into a few O/D pairs

Fast Reliable

Metro Attributes

Actions

Comfort Low waits

Increase

Regular

Increase

Capacity

Increase

Frequency

•Segregated ways/lanes and priority at junctions

•Reduce dwell times

•Fare payment off-bus

•Buses with multiple doors

•Express services

•Traffic signal priority and priority at intersectons

Anticipated Green Light for Buses

R. Fernández

• Move pedestrian crossing

• “Do not block”

Protection of Buses on Right Turns

P. Furth

• Move pedestrian crossing

• “Do not block”

• Exclusive phase for

pedestrian

P. Furth

Protection of Buses on Right Turns

Metro Attributes

Actions

Increase

Regular

Increase

Capacity

Increase

Frequency

•Segregated ways/lanes

•Reduce dwell times

•Fare payment off-bus

•Buses with multiple doors

•Express services

•Traffic signal priority and priority at intersectons

•Improved headway control

Fast Comfort Low waits Reliable

Santiago, Chile

Time-space trajectories Line 201, March 25th, 2009

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 3000

Tiempo (minutos)

ión (

6:30 AM 8:30 AM

Boston, MA; line 1 during winter

Boston, MA; line 1 during summer

Is keeping regular headways that

difficult?

Transit Leaders Roundtable MIT, June 2011

Ricardo Giesen ©

Stop Stop

Waiting

Passengers

Waiting

Passengers

Bus Operations without Control

Ricardo Giesen ©

Bus Bus Stop Stop

a small perturbation…

Waiting

Passengers

Waiting

Passengers

Ricardo Giesen ©

Stop Stop

While one bus is still loading passengers the other bus already left its

last stop

Ricardo Giesen ©

Bus Stop Stop

Ricardo Giesen ©

Stop Stop

Without bus control, bus bunching occurs!!!

Stable versus unstable equilibrium

+ - + - + - +

And so on so forth. Our challenge is to keep an inherently unstable system: buses evenly spaced Now, if we want to prevent bunching from occurring … when is the right time to intervene?

Bus bunching is

specially serious,

where bus capacity

is an active

constraint.

Bus bunching

Severe problem if not controlled

Most passengers wait longer than they should for crowded

Reduces reliability affecting passengers and operators

Affects Cycle time and capacity

Creates frictions between buses (safety)

Put pressure in the authority for more buses

Contribution: Control Mechanism to Avoid Bus Bunching

based on real-time GPS data

2. Research

Propose a headway control mechanism for a high frequency & capacity-

constrained corridor.

Consider a single control strategies: Holding

Based on real-time information (or estimations) about Bus position, Bus

loads and # of Passengers waiting at each stop

We run a rolling-horizon optimization model each time a bus reaches a

stop or every certain amount of time (e.g. 2 minutes)

The model minimizes:

Time waiting for first bus + time waiting for subsequent buses + time held

No control

Spontaneous evolution of the system.

Buses dispatched from terminal as soon as they arrive or until the design headway is

reached.

No other control action is taken along the route.

Threshold control

Myopic rule of regularization of headways between buses at every stop.

A bus can be held at every stop to reach a minimum headway with the previous bus.

Holding (HRT)

Solve the rolling horizon optimization model not including green extension or boarding

limits.

Estrategias de control simuladas 3. Experiment: Control strategies

4. Results: Simulation Animation

Simulation includes events randomness

2 hours of bus operation. 15 minutes “warm-up” period.

No HRT

control

Wfirst 4552.10 805.33

Std. Dev. 459.78 187.28

% reduction -82.31

Wextra 1107.37 97.49

Std. Dev. 577.01 122.59

% reduction -91.20

Win-veh 270.57 1649.28

Std. Dev. 36.00 129.56

% reduction 509.57

Tot 5930.03 2552.10

Std. Dev. 863.80 390.01

% reduction -56.96

Results: Time savings

Results: Time-space trajectories

0 20 40 60 80 100 1200

10s2 NETS sc corrida17

tance (

Time(minutes)

0 20 40 60 80 100 1200

10Scenario 1 threshold run17

tance (

Time(minutes)

No Control

This impacts comfort, reliability for users and for operators

Results: Bus Loads

0 5 10 15 20 25 300

120Scenario 1 HBLRT alpha=05 Beta=05

Load (

0 5 10 15 20 25 300

120Scenario 1 HBLRT alpha=05 Beta=05

Load (

No Control

Results: Cycle Time

25 30 35 40 450

mean =33.64

Std.Dev. =3.51

No control

quency

Cycle Time (Minutes)

25 30 35 40 450

mean =32.11

Std.Dev. =1.2

HRT 05

quency

Cycle Time (Minutes)

HRT No Control

Results: Waiting time Distribution

% of passengers that have to wait between:

Period 15-25 Period 25-120

0-2 min 2-4 min > 4 min 0-2 min 2-4 min > 4 min

No Control 57.76 29.60 12.64 63.46 27.68 8.86

HRT 79.24 20.29 0.47 87.30 12.62 0.08

Disobeying Drivers

Similar disobedience across all drivers

A subset of drivers never obey

Technological

Disruption

Random signal fail

Failure in the signal receptor equipment

Signal-less zone

Homogeneous distribution across buses

Concentration in certain buses

Concentration in certain stops

5. Impact of implementation failures

Impact of implementation failures

Common disobedience rate across drivers

0%10%20%30%40%50%60%70%80%90%100%

Obedience rate

HRT, Beta=0,5

Sin Control

Full disobedience of a set of drivers

0 1 2 3 4 5 6 7

Deaf Buses from a total of 15 buses

6. Implementation

• The tool has been tested through two pilot plans in

buses of line 210 of SuBus from Transantiago (Santiago,

Chile) along its full path from 7:00 to 9:30 AM.

• We chose 24 out of 130 stops to hold buses

• One person in each of these 24 stops received text

messages (from a central computer) into their cell

phones indicating when each bus should depart from the

Plan Description

Implementation

Real time GPS information of each bus

Program optimizing dispatch times for each bus from each stop

Text messages were sent automatically to each person in each of the 24 stops

Buses are held according to the text message instructions (never more than one minute)

Control Points

The results were very promising even though the conditions were far

from ideal

Main results • Transantiago computes an indicator for

regularity based on intervals exceeding twice the expected headway (and for how much).

$ 10.000

$ 20.000

$ 30.000

$ 40.000

$ 50.000

$ 60.000

$ 70.000

$ 80.000

$ 90.000

$ 100.000

$ 110.000

Main results: cycle times

2:24:00

2:31:12

2:38:24

2:45:36

2:52:48

3:00:00

3:07:12

3:14:24

3:21:36

3:28:48

3:36:00

5:52:48 6:00:00 6:07:12 6:14:24 6:21:36 6:28:48 6:36:00 6:43:12 6:50:24 6:57:36

Dispatch time

Piloto 1

Prueba10

Prueba12

Prueba13

Prueba15

Prueba16

Prueba17

No significant differences for cycle times

• Line 210 captured an extra 20% demand!

94.000

96.000

98.000

100.000

102.000

104.000

106.000

7.400 7.600 7.800 8.000 8.200 8.400 8.600 8.800

Demand for Line 210 (pax)

Demand on All lines

Unexpected result

7. Conclusions

Developed a tool for headway control using Holding in real time reaching

simulation-based time savings of 60%

Huge improvements in comfort and reliability

The tool is fast enough for real time applications.

Two pilot plans have shown significant improvements in headway regularity.

During 2013 we will build a prototype to communicate directly to each driver.

Other activities

• Three chilean operators will test our tool this year

• Raised interest from operators in Cali and Istanbul

• A research and development team is consolidating

• Pedagogic tool to teach bus headway control

Future of BRT: Flexible Capacity Operations

Juan Carlos Muñoz and Ricardo Giesen Bus Rapid Transit Centre of Excellence

Pontificia Universidad Católica de Chile

July 12, 2013

Theme 4 Flexible capacity operations

Business