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
much
Can we provide Metro-like service with buses?
• Fast
• Low wait time
• Comfortable
• Reliable
• Good information
• Branding
Can we provide Metro-like service with buses?
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)
Can we provide Metro-like service with buses?
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
time
•Higher comfort
•Reliability
Source: Frits Olyslagers, May 2011
Fast Reliable
Metro Attributes
Actions
Comfort Low waits
Main drivers
Increase
Speed
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
Speed
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
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
Speed
Regular
Headways Main drivers
Increase
Capacity
Increase
Frequency
•Segregated ways/lanes •Reduce dwell times
•Fare payment off-bus •Buses with multiple doors
•Increase distance between stations
Low waits
Fast Reliable
Metro Attributes
Actions
Comfort Low waits
Increase
Speed
Regular
Headways Main drivers
Increase
Capacity
Increase
Frequency
•Segregated ways/lanes •Reduce dwell times
•Fare payment off-bus •Buses with multiple doors
•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
Speed
Regular
Headways Main drivers
Increase
Capacity
Increase
Frequency
•Segregated ways/lanes and priority at junctions
•Reduce dwell times
•Fare payment off-bus
•Buses with multiple doors
•Increase distance between stations
•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
Speed
Regular
Headways Main drivers
Increase
Capacity
Increase
Frequency
•Segregated ways/lanes
•Reduce dwell times
•Fare payment off-bus
•Buses with multiple doors
•Increase distance between stations
•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
2.5
5
7.5
10
12.5
15
17.5
20
22.5
25
27.5
30
32.5
35
Tiempo (minutos)
Posic
ión (
Km
.)
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 ©
Bus
Bus
Stop Stop
Waiting
Passengers
Waiting
Passengers
Bus Operations without Control
Ricardo Giesen ©
Bus Bus Stop Stop
a small perturbation…
Waiting
Passengers
Waiting
Passengers
Bus Operations without Control
Ricardo Giesen ©
Bus
Bus
Stop Stop
While one bus is still loading passengers the other bus already left its
last stop
Bus Operations without Control
Ricardo Giesen ©
Bus
Bus Stop Stop
Bus Operations without Control
Ricardo Giesen ©
Bus
Bus
Stop Stop
Without bus control, bus bunching occurs!!!
Bus Operations without Control
Stable versus unstable equilibrium
Stable versus unstable equilibrium
Stable versus unstable equilibrium
Stable versus unstable equilibrium
Stable versus unstable equilibrium
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
buses
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
1
2
3
4
5
6
7
8
9
10s2 NETS sc corrida17
Dis
tance (
Km
)
Time(minutes)
HRT
0 20 40 60 80 100 1200
1
2
3
4
5
6
7
8
9
10Scenario 1 threshold run17
Dis
tance (
Km
)
Time(minutes)
No Control
This impacts comfort, reliability for users and for operators
Results: Bus Loads
0 5 10 15 20 25 300
20
40
60
80
100
120Scenario 1 HBLRT alpha=05 Beta=05
Load (
Pax.)
Stop
HRT
0 5 10 15 20 25 300
20
40
60
80
100
120Scenario 1 HBLRT alpha=05 Beta=05
Load (
Pax.)
Stop
No Control
Results: Cycle Time
25 30 35 40 450
50
100
150
200
250
300
350
mean =33.64
Std.Dev. =3.51
No control
Fre
quency
Cycle Time (Minutes)
25 30 35 40 450
50
100
150
200
250
300
350
mean =32.11
Std.Dev. =1.2
HRT 05
Fre
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
8000
9000
10000
11000
12000
13000
14000
15000
0%10%20%30%40%50%60%70%80%90%100%
Tota
l W
aiti
ng
Tim
e [M
in]
Obedience rate
HRT, Beta=0,5
Sin Control
Full disobedience of a set of drivers
8000
9000
10000
11000
12000
13000
14000
15000
16000
0 1 2 3 4 5 6 7
Tota
l W
aiti
ng T
ime
[Min
]
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
stop.
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
Mu
ltas
($
CLP
)
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
Cyc
le t
ime
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
(pax)
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
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