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NEEMA NASSIR: Let's go ahead and start.
Good afternoon, everyone.
My name is Neema Nassir.
I'm a post-doctoral associate at Transit Lab, MIT.
I've been invited to give a few lectures in this course
and basically participate in delivering the course
material for this course.
I will be talking in this session
and in the next session on Short-range Planning Practice.
And then I'll be back again in April and in four sessions
in April, lecture number 13, 14, 15, and 16
dealing with vehicle scheduling, crew scheduling, network
and root structure and high ridership corridors.
So let's go ahead and start.
In this session, we are going to talk about short-range planning
practice.
And basically, I will give a brief set of definition
and concepts and introduction to the planning
activities that are usually made at transit authorities
in the US and also worldwide.
And then we will briefly talk about the measures
and the standards and guidelines that are published and used
by transit agencies to plan their service based on those.
Then we will also talk about current practice and critique
of the existing systems.
Probably we will cover icon 1 and some material in icon 2
this week.
And then the rest will actually be delivered to you
in our session next Tuesday.
So the planning decisions and the planning activities that
are usually done at the transportation planning
agencies and public transport planning agencies usually can
be classified into four different type of decisions
depending on frequency of decision-making and the need
for making decisions and the scope of decisions--
the scope of changes that are related to the decisions that
are made with each activity.
These planning activities are divided
into four different classes--
long range planning activities, medium range, short range,
and control.
Long range planning activities basically include
major capital investment--
major improvements to the infrastructure--
which would include construction of a new station, a new rail
line, a new bus way to the system.
Or it could also be related to and as a result
of major institutional changes and changes to the, basically,
financial resources of the organization.
The decisions that [INAUDIBLE] involve long range planning
are usually driven by political and economic considerations.
And basically, the type of analysis
and the type of planning that is done in long range planning
activities involve projection into the future and prediction
of demand and prediction of situation in the future.
Therefore, it requires a comprehensive analysis
usually for any strategic planning of interactions
between changes in land use and interaction
between land use and demand in the future.
And it basically needs to capture or have, like,
an insight into the future of the network and of the region.
The next range is basically or the next class
of planning activities is basically
the medium range activities.
Medium range activities include bus network structure design,
network size design and improvement, fleet size,
fare policy and technology.
It basically involves incremental or medium
improvement to the system and to the transit service.
One point that I need to mention about the long range and medium
range is that these two, although
are really important in the planning
practice for transportation systems,
but these decisions are usually done at the upper level--
at the higher lever than the transit authority.
For example, long range decisions
are usually done in collaboration
between NPO's metropolitan planning organizations,
state departments of transportation,
and transit authorities.
So the transit authority is not the final decision maker
in that case.
And it needs close interaction and close collaboration
with the higher level organizations
and governmental agencies to make the final decisions.
So that's about the long range.
Medium range is also somehow similar.
It usually, for example, the decisions
that are related to the network structure, although there
is a lot of interesting research going on in universities that
deals with optimization of network design and optimization
of the structure of the network, because what happens
in practice is that usually in the networks that we live
and in current cities, the actual layout and structure
of the network is already given.
And it's usually rare or impossible that we
start from scratch and start to design a network from scratch
to begin with.
So therefore, what we usually observe
is incremental changes to the network and addition
or elimination of some routes from the service and basically,
decisions that are related to that.
AUDIENCE: I have a question.
NEEMA NASSIR: Yes, please.
AUDIENCE: In terms of fleet size,
could that come as a request from the agencies?
Like, an agency says, we have a bus line.
It's at capacity or over capacity.
We need more buses.
Could it come, like, from a request to the higher level?
NEEMA NASSIR: Yes, definitely.
Yeah, but it eventually requires the interaction on those,
so securing the funding from the upper level
governmental agencies--
so yeah.
So the reason that I'm explaining this
is that I'd like for you to understand why we are focusing
on short range decision-making and short range planning
practice in this course.
That's mainly because the bulk part of activities at transit
agencies is related to short range planning and short range
decision-making.
So what we mean by short range decision-making
are decisions that are usually made more frequently
than a yearly basis.
And they basically entail decisions
about the structures of the route--
layout of the route-- layout of the stops--
and basically decisions about the frequency of service--
timetable-- and vehicle and crew scheduling.
Despite the top two classes of decision-making
that are usually driven by political and economic
considerations, short range decision making
and control activities are usually basically driven
by cost optimization.
And these are basically tactical decisions as opposed
to strategic decisions that are usually in the long range
and medium range.
So then there's real time and control decision-making,
which is basically usually done currently
in using expert decision and expert activities.
There is an ongoing effort in the technology
to improve the quality of control--
ongoing research to use real time data
and improve the real time performance
by using real time control.
This includes revisions of the routes.
That could be the case in reaction
to incidents and disruption situation.
It could also relate to holding and dispatching decisions--
thank you--
that could actually be used to improve
the effective capacity of the system by trying to regulate--
have a better frequency, basically, in the service.
So similar to the typical planning problem,
there are major elements in planning
for public transportation and particularly
in short term and short range decision-making.
It includes data collection similar to what
you guys have done in your homework assignment number 2.
Collection of data on demand, collection of data on supply,
and interaction of supply on demand
is an essential part to be able to make decisions and make them
basically reliable and actionable intelligence
for the decision-making process.
Then there should be analysis on identification
of potential problems and identification of opportunities
to improve the situation.
And then there is the creative part
of design of options, solution, and strategies
to address the situation.
And then typical to any economic analysis,
there would be an element of cost
and benefit estimation to be able to justify the project.
So in terms of operational planning process
or in another term short range planning process,
there are multiple stages involved in the work.
And usually, what happens is that in practice,
it is proven that the planning procedure
can be decomposed into sequential decision-making
processes.
And although it is possible to formulate
all of these decisions into one gigantic optimization problem
and solve it for all the decision variables
that you need to basically address, however,
the practice has shown that there's
a nice way of decomposing the process
and to solve problems and solve them sequentially in order
to make sure that you're satisfying
all the constraints to the accurate level
and you're gaining the--
you finally get a realistic optimal solution
for your planning practice.
Considerations regarding policy constraints and some
of the economic concerns are usually
difficult to formulate into optimization problems.
But there are published guidelines
by governmental agencies that you can basically
follow and make sure that at least the top two
level of the decision-making processes and tasks
here are basically done to the satisfactory level.
So let's go ahead and start and review these tasks.
There are lectures in this course that
are dealing with each one of these tasks
and components in planning.
But in this lecture, I'll just briefly
go over these different components
as an introductory part of the course.
So for every optimization problem
or in this case planning process,
we have a set of inputs--
constraints-- basically, that you need to satisfy.
And then there's an objective function
that you need to optimize-- so inputs.
So the first component of the planning and practice
here is bus route design.
This includes design of layout of the routes
and layout of the stops.
And basically, the input into this task
includes constraints that are related to right-of-way roadway
constraints, like if there is a river in your network,
there's this connectivity.
There are bridges-- tunnels.
So these are the kind of constraints at network level
that you would like to satisfy.
And there's also demand constraints in the network
that you need to consider for this task,
like, you have a sense of what's the demand from certain suburb
to the downtown area.
And you basically would like to have a route
system that kind of can address that demand
and satisfy that demand.
Then the solution to the design component and that task
[INAUDIBLE] out of routes and layout
of the stops that are basically resulting
from the first component, and then
the set of routes and stops will be
input into the second task, which is setting timetables.
This task includes finding frequencies for the routes
and from that identifying and defining--
basically, generating the timetables
based on frequencies.
There are usually considerations related to policy headways,
policy frequencies, and capacity frequencies
that need to be addressed in this task.
But again, this task is also somehow dealt
with using the existing guidelines
and just satisfying these guidelines.
The input and other constraints that
are considered for this task would
be level of service guidelines, and again,
the demand constraints in the network.
Then from the set of timetables, what will be resulted here
is the departure times that was scheduled for the service.
So the first two components of row 1 and row 2,
basically, are dealing with satisfying the demand
and satisfying the guidelines.
But once you go beyond the first two components,
it becomes to the level that you know
kind of what's the service you want to deliver.
And then you're dealing with tactical decision--
how you can optimize the cost of delivering this service
and improve efficiency.
So did the third row here basically deals
with the departure times that are
given for all the routes in the network
and for all times of day.
And then what you need to do is how
you want to allocate your resources in terms
of allocate the vehicles to the system
to make sure that that service is
going to be delivered on time.
So that would be the task of vehicle scheduling input
into that task or constraints that are involved
or running times on different segments of the route
and also the departure times that are given from upper level
decision-making process.
And it will eventually result into a schedule
of given buses in terms of what are specific trips they
need to serve and what's the sequence of these trips.
Then the output from that decision with the vehicle
schedules into the task of scheduling for drivers,
this task also include input from operator
and basically work union constraints,
like maximum shift hours and, for example, like,
break times and lunchtimes and maximum separation
between two shifts.
And there are rules and regulations
that are related to that.
And this task, again, is a task of allocating resources
to minimize the cost of scheduling drivers
to deliver the service.
And the result would be the schedules for the crew.
So then these decisions can be looked at in another way,
too, like, we can further classify these decisions
into service planning decisions and operational planning
decision.
Service planning decisions would be the decisions
that define service as it is perceived and understood
by public.
This is basically the part of service
that is visible to the public.
And then there are decisions that
are related to operations, which basically
defines how operations occur to produce the service.
This is somehow a black box to the passengers.
And yeah, basically, the passengers
should not really care what's the vehicle's schedule
and what's the crew's schedule that is assigned to the trip,
as long as trip is being delivered as it is scheduled.
So in terms of other characteristics
of these decisions, we, basically,
for network design frequency setting time table development,
vehicle scheduling, and crew scheduling,
the decisions that are involved in planning, basically,
starting from top to bottom frequency of decisions,
basically are increased.
And the scope of decision-making into the future
is basically become limited and smaller.
And also, the decision-making in the network design frequency
setting and timetabling is basically
made based on guidelines and standards.
And decision-making on the lower level-- vehicle scheduling
and crew scheduling-- is made usually
based on optimization of cost.
And then given the nature of the decision-making, the tools that
are used and the techniques that are
used for solving these planning decision-making processes
are basically ranging from judgments and manual analysis
that is more dominated into computer tools that
are basically designed to solve optimization problems
for minimizing the cost.
So similar to the classical evaluation structure,
when you're dealing with planning questions and planning
projects or planning alternatives,
there's this structure that starts with goals, objectives,
measures, and standards or guidelines.
So let's just make a quick practice and define a goal
and then define objectives for that goal,
and define measures based on that,
and see how a standard can be defined to make that planning
decision acceptable.
So let's define a goal.
Does anyone have any suggestion?
What is an important goal for public transportation system?
AUDIENCE: Maximize ridership.
NEEMA NASSIR: Maximize ridership, yes.
So let's say you want to maximize ridership.
That's your research problem, right?
AUDIENCE: [CHUCKLING]
NEEMA NASSIR: [CHUCKLING]
AUDIENCE: [INAUDIBLE]
NEEMA NASSIR: Right.
[LAUGHTER] So then in terms of objectives,
what would be an objective that we can define for this?
I would say probably the peak hour demand
could be one objective or peak hour
ridership in certain corridor.
Let's say peak hour ridership per weekday per month.
Well, peak hour ridership would be the objective here.
And then the measure that you would define
would be peak hour ridership per weekday per month.
And then the standard that you want to define
would be something that not only captures
the demand side, but also the supply of the system, too.
So you would come up with probably, like--
I would, like--
AUDIENCE: Riders per vehicle--
riders per mile-- per hour.
NEEMA NASSIR: Yeah, exactly.
Or let's say, like, 60% of capacity.
Like, your standard in this case would
be your peak hour ridership should be greater than 60%
of capacity.
So this was just an example that we
tried to work out one practice for evaluation structure.
But let me give you another example that is actually
used in the practice.
So assume that we are considering
the goal of reliability in the transit system.
The goal of reliability would be considered
one of the main goals because if we
have a reliable public transport system, you can secure
and you can guarantee a body of demand
in your network that can rely on your transit system
and basically adapt to the lifestyle of using
public transport.
And that's beneficial to the system
from different perspectives.
So the objective that we can define
for reliability in this case would be possibly--
can you come up with some objective
that we can define with the goal of improving reliability?
AUDIENCE: On-time performance.
NEEMA NASSIR: On-time performance, yes.
So on-time performance would be the objective.
And then we need to define a measure for this
to be able to measure that objective
for each one of the scenarios and for each one
of the alternative plans.
So what would be a measure for on-time performance?
AUDIENCE: Characterizing with our car driving [INAUDIBLE]
within a certain amount of time.
NEEMA NASSIR: Right, yeah.
So let's say percentage of on-time arrivals.
So we would say percentage of on-time arrivals,
and we would define on-time arrivals
to be between 0 and 5 minutes of the schedule.
And then the standard that many of the agencies
use to measure this would be 90% or 95%, basically.
So this way, the transit agency can
go ahead and evaluate the performance of the operators
of the system who basically are running
some part of the service and come back to them
and say, OK, your performance in terms of reliability
has been acceptable or not.
Please.
AUDIENCE: [INAUDIBLE] something [INAUDIBLE]..
Or would it be just standard operating procdedure
they were planning as well.
And their reliability was somewhere around 80%,
and now the goal is to achieve a 10% gain.
NEEMA NASSIR: Mm-hm.
AUDIENCE: And comparing that with the previous one would
be a benchmark again.
NEEMA NASSIR: Yeah, exactly.
So another measure would be percentage improvements as
compared to baseline.
And then the transit agency can define a standard
of at least 10% improvement to the baseline
should be required for reliability.
Yep, thank you.
So then one other interesting point
that actually comes to mind looking at the existing
guidelines is that on-time arrivals are usually
defined for 0 to 5.
That basically means that you consider
a bus that is late by two minutes to be on time.
But a bus that is early by one minute
is not considered to be on time.
Does anyone have any comments about this--
why we do not consider early arrivals on time?
AUDIENCE: I think misconnections for people
who expected to be there at a certain time, but--
NEEMA NASSIR: Right, yeah.
AUDIENCE: --they left.
NEEMA NASSIR: Yeah, yeah.
AUDIENCE: [INAUDIBLE] connected.
NEEMA NASSIR: So it can be proved
that based on typical assumptions about passenger
arrivals, early arrivals of buses and service
is usually more negative as later arrivals.
Let's make an example here.
For example, let's assume under uniform arrivals
of passengers--
let's assume if this is my scheduled
arrivals over the axis of time and this
is my number of passengers waiting in the bus stop
under uniform arrivals, [INAUDIBLE]
you have some accumulation of passengers
that are waiting at the stop.
And then what happens is that if one of these buses are early--
let's say it basically arrives at this time--
what happens is that the amount of time
that we are saving due to this arrival
is basically less than the amount of time that
will be added to our waiting time for the next trip.
And that's because the number of people who are experiencing
this is a little higher--
number of people that experience it,
saying, the additional waiting time
is higher than number of people who are
experiencing the early arrival.
And it cuts to their waiting time.
So if you compare these two areas, that basically tells you
you're basically having a loss or having
an increase in waiting time if your service is early.
And then the situation becomes worse--
indicates that you suggested-- when people are coordinating
with the system--
for example, it is assumed that--
and it can actually be proven by looking at the data, too--
people make the transition to coordinated behavior
and coordination with the schedule as the frequency
of service increases.
For example, for a service that is scheduled
to be delivered every half hour or every one hour,
it is expected that passengers are
coordinating with the system and coordinating
their arrivals with the departure of the buses.
But when it comes to more frequent service,
then we will have more uniform arrivals.
So in that case, what we would observe
is that passengers arrivals would resemble something
like this.
Well, it has to go up to here, the original case.
And then in that case if your service early by five
or 10 minutes, you will have the main bulk of your passengers
who need to wait another headway, basically.
So this should be actually added to your computation, too.
Is there any questions about this?
So in terms of the advantage of guidelines in transit planning,
one of the main purposes of these guidelines
is to communicate to the public the rationale
and the logic behind your decision-making
and behind your allocation of resources to the system.
It also gives you a consistent and fair basis
for decision-making.
And it is somehow gives you a tool to justify your decisions
and also a tool to make sure that your decisions are
fair and justified in nature.
It also gives you the opportunity
to balance the improvement and the investments to the network
and gain a uniform level of service improvement
for efficient service.
So the guidelines that are existing in the literature
and in the practice, basically-- in the state of practice--
are dealing with the design of service
and with the delivery of service.
So the design of service basically dealing
with variables that are related to spacing
and density of stops, spacing and density of trips,
and frequency of the service as it is designed and as it
is in the schedule.
So there are guidelines related to that.
And there is also guidelines related to how you deliver
or how the transit agency delivers the design service
and how the performance actually took place.
So the main factors of service design and service quality
from the passenger's perspective are basically
reported by transit capacity and quality
of service manual of the Transportation Research Board.
And it basically includes frequency of the service as one
of the main aspects or factors that are defining
the quality of service--
waiting time, reliability, and access.
This is access over time and also access over space.
So why do we again have both frequency and waiting
time in here?
So if frequency and waiting time are kind of interrelated,
how come there are two separate items here on the list here?
Does anyone have any suggestions about this?
So let me go ahead and explain how I understand this.
Frequency of the service is important not only
in terms of the waiting time--
that could be associated with that--
but also when it comes to lower frequency system and longer
headways.
The waiting time is not a function of frequency anymore.
It basically, as we discussed, the waiting time
could actually be independent of frequency.
However, in those cases, there is a burden of coordination
that is imposed to the passenger.
So if you have to coordinate your arrival, for example,
in the morning from home to work,
then there is some sort of inconvenience
that is imposed to you to basically make it
to your coordinated schedule.
And then waiting time is also important
because if the service is frequent
but at different ranges of frequency,
you may experience different waiting time
if the process of arrivals of passenger
is assumed to be a random process.
Then reliability as we discussed is
one of the important features and one
of the important aspects of the service.
It usually is a measure based on on-time arrivals
of the service.
And then the next aspect that is important
is access to origins and destinations.
This access can be interpreted in two ways.
We can look at access in terms of space and in terms of time.
Access in terms of space is closeness to the bus stops
and closeness to the service from origin
and from the destination.
Access in terms of time would be the span of service--
when you like to travel--
and basically, what is the service time
and available times of service.
So yeah, as I mentioned, most agencies
have guidelines covering a span of service.
For example, MBTA has this guideline
that for weekdays, you need to have service from all suburbs
into the CBD area with--
at least, like, at latest, arrives at 7:00 AM.
So you need to basically be able to cover between 7:00
AM and 6:00 PM as your services span in MBTA.
For TransLink, it's also somehow the same.
You need to-- basically, minimum service guidelines
to ensure that 95% of trips listed
can be completed in the time span given below.
Like, from any point to downtown Vancouver,
you need to have service that can actually
arrive in downtown Vancouver by 7:00
AM, for people who should start their work at 7:00 AM.
And then there's also trips in the evening.
And it basically says earliest departure time of mass transit
trip in the evening from downtown Vancouver
to any town center needs to be midnight for people
who basically would like to enjoy
the nightlife in the downtown area
and then use transit to go back home.
So in terms of route design and in terms
of layout of routes and stops, there
are also guidelines that are addressing this decision.
MBTA has a policy objective to provide transit service
within walking distance, which is defined a quarter
mile of all residents that are living in area with population
densities greater than 5,000 people per square mile.
That's basically an interesting guideline.
It considers two different variables.
One is the population density.
And the other one is the density of the stops or vicinity
or walkability of transit in areas
that are populated with densities greater than 5,000
per square mile.
So in terms of comprehensiveness objective,
TransLink basically has very comprehensive guidelines
related to basically a set of different performance measures
and goals.
Let me read from these.
At least 90% of our residents and employees
in urbanized development areas should
have a walk less than 450 meters to a bus stop.
So this is related to access over space.
98%--
AUDIENCE: When they say 90% of residents and employees,
basically they're looking at that person twice.
The person is on one end, a resident,
and on the other end, an employee.
NEEMA NASSIR: Right, yes.
AUDIENCE: So it's-- OK.
NEEMA NASSIR: Yeah, you want to consider both ends of the trip,
right?
And these percentages are a little tricky.
Sometimes they're counting the number of people-- number
of residents.
Sometimes they're counting OD pairs.
Sometimes they're counting passengers.
So it's a little tricky to interpret these correctly.
So the second one basically says 98% of all peak period transit
trips to and from downtown Vancouver
should require no more than one transfer.
That basically is 98% of people who are traveling from
and to downtown to the suburbs.
And so it may be a little difficult, especially
in the absence of AFC data--
Automated Fare Collection system data.
It can be a little tricky to measure these objectives.
What's usually done, basically, is
people go out and basically ask from transit riders
about their origins and destinations.
It's called Public Transit Origin Destination Survey
that is usually done on board.
Do you have a question?
OK.
So the second measure here relates
to connectivity in the network.
The third one is 95% of all peak period
transit trips to the nearest town centers
should require no more than one transfer.
Again, this one is also related to connectivity of the network.
And fourth one is all trips between one town center
and adjacent town centers should require no transfers.
Again, this one is a guideline on connectivity.
And then again, the last one is also on connectivity.
It basically requires that 95% of all peak period transit
trips to major regional activity centers and gateways
should require no more than two transfers.
OK, so any questions or comments about this?
AUDIENCE: Yeah.
NEEMA NASSIR: Yeah.
AUDIENCE: In terms of one connectivity between one town
center and adjacent town center, definition of a town
varies from place to place.
NEEMA NASSIR: Mm-hm.
AUDIENCE: I know that specifically Vancouver
has rather large suburbs--
like, suburbs of 100,000 people--
200,000 people.
So you actually have a few municipal entities
for a large area.
NEEMA NASSIR: Mm-hm.
AUDIENCE: But you can have areas where that condition would
be a little bit too strict if you have, let's say,
the Boston area, which is generally
slightly smaller suburbs and more suburbs to connect.
NEEMA NASSIR: Right, yeah.
So some of these may actually be a little tricky
to measure and to quantify.
AUDIENCE: Yeah.
And they're able to compare.
NEEMA NASSIR: Right.
AUDIENCE: Yeah, when I see these numbers, then I
try to think about equity, and, like, the 10% that is not 450--
NEEMA NASSIR: Right.
AUDIENCE: --is it from that or--
NEEMA NASSIR: Yeah.
AUDIENCE: --a bus station--
NEEMA NASSIR: Right.
AUDIENCE: --[INAUDIBLE] the 5% .
NEEMA NASSIR: Mm-hm.
AUDIENCE: So how do you navigate these types of trade-offs
in the face of equity.
NEEMA NASSIR: Right.
This is a really good point.
Some of these percentages, I think,
are related to random variables.
And those are somehow acceptable because that's
when you try to define a confidence interval.
But when it comes to cases like this,
it is not a random variable anymore.
It's basically like a special variable that constantly
requires a certain amount of connections to the downtown
area, right?
So that may be one of the loopholes of this guideline.
That's a really good point because one
may argue that if 95% of my OD pairs
are connected with the minimum connectivity requirement,
what about the rest of 5%?
Does it mean that all people who live in that 5% area
will have to go through the unacceptable connectivity
situation?
So that's a valid point.
And thank you for bringing that up.
AUDIENCE: Does Vancouver actually achieve these goals?
It seems kind of implausible-- kind of difficult to--
NEEMA NASSIR: Right.
AUDIENCE: [INAUDIBLE]
NEEMA NASSIR: Yeah, well, these are basically usually
for projects and plans that are being proposed
for-- or like small start projects
or for improvement plans.
So I think what they try to do is to make sure
that the ones that are being accepted and being implemented
would satisfy this.
But I'm not really sure if the existing network satisfy
all these conditions or not.
AUDIENCE: Yes.
AUDIENCE: Sorry, is TransLink the name
of the agency that runs the--
NEEMA NASSIR: Yes, right.
Yeah, right.
OK, so any other questions?
All right.
So then TransLink guideline on route design
is very interesting, too.
They have really interesting logic
to validate the design and the improvements that
are proposed for route design.
So what it says is that deviations from the most direct
route must have walking time savings for customers
on the added route section greater
than the increase in total travel time
for through passengers.
So does anyone have any interpretation--
quick interpretation-- on this guideline?
AUDIENCE: The only reason is [INAUDIBLE] a major destination
where people [INAUDIBLE] or otherwise people
are going straight and what [INAUDIBLE] people on buses.
So the second to the last stop on the route,
may be you make that deviation to have
people on the bus [INAUDIBLE] traffic [INAUDIBLE]
NEEMA NASSIR: Right.
Yeah.
Right.
You have a comment, too?
AUDIENCE: [INAUDIBLE]
NEEMA NASSIR: Right, yeah.
So if you look at the problem or look at the situation
from the perspective of system and from the perspective
of total travel time in the system, what they basically
are requiring is that, for example,
let's assume that I have a suburb here.
And then this is my downtown area.
And there is a route here that has multiple stops.
And then there's another suburb here,
which, in the original plan is being served by this route.
However, it requires a walking link to different stops.
What this guideline basically requires is that if the total
travel time for all passengers for traveling from here to here
and for all that are traveling from here to here is going
to be increased, then you cannot justify an additional detour
here to serve this area, meaning that if the total travel time
saving that is done on the walking time of these people is
not as much as total increase in travel time of people that are
traveling from this suburb to this suburb,
then you cannot justify the design or the re-route.
So in terms of guidelines related
to a schedule and guidelines related to frequency
and timetable, we basically, in practice there
are two main components-- component
that is related to the policy of design and components
that is related to the crowding situation.
Policy of design basically dictate a minimum headway
or basically a minimal frequency or maximum
headway for the service.
And that's basically the case when
there is no crowding situation.
However, in the main corridors and in peak directions,
we usually would go beyond the service of policy headway
because we need to accommodate the demand.
And that's basically how the maximum passenger crowding
guides come into play.
So in terms of the actual guideline on policy of headway
for MBTA, we have maximum headway
on all local bus routes should be 30 minutes in peak
and 60 minutes at other times.
For express routes, there should be at least three trips
in each peak period.
So let's discuss a little bit more about this.
Why do you think that we need to have a policy headway--
maximum policy headway?
If we are considering the demand and we
are trying to satisfy the demand by number of vehicles
that we are assigning to the route,
then why should we care about a minimum?
Do you--
AUDIENCE: Because if the demand is really low,
that person-- you can't make him wait forever.
NEEMA NASSIR: Yeah.
AUDIENCE: You'll have to serve him equitably.
NEEMA NASSIR: Exactly, yeah.
Again, the equity issue and the accessibility issue, basically.
AUDIENCE: And there are also, you know,
still elderly people who don't use smartphones
to coordinate their arrival at the bus
stop when the bus is coming.
NEEMA NASSIR: Right.
AUDIENCE: And you don't want to make them wait indefinitely.
NEEMA NASSIR: Right, exactly.
Right.
OK, and then when it comes to considerations related
to the crowding, we have guidelines
about maximum crowding and maximum expectation
of crowding that would dictate a minimum frequency
for the service.
For example, for Green line, the maximum passengers per car
should be no more than 225% of the seats in the peak period.
In the off peak, the maximum passengers
should be no more than the seated capacity,
except in the central subway, which can go up to 140%.
Yeah, so here is the TransLink guideline
on frequency objective.
It basically defines different headways based on time of days
and based on modes of transit that the transit agencies
and operators of the system need to satisfy.
So in terms of guaranteeing that the load and the crowding
situation is addressed in the guideline that
is related to frequency, there is some analysis
that is done to make sure that your frequency is high enough
that your crowding situation does not
exceed a certain level.
Why do we care about the loads and the crowding situation?
The first reason is that we do not want
to frequently deny to board.
That would yield to increased travel time.
And we would like to basically avoid higher dwell time that is
associated with higher number of boardings--
alighting number of wheelchairs on board--
that would eventually, again, increase the running time.
For example, in the acceptable--
in a regular standard 40-foot bus
the acceptable load of 70 passengers are considered.
However, the average that we estimate based on our design
should not exceed 55 passengers.
So that's the case of indeterminacy
and the confidence intervals that we kind of allow
in the analysis.
However, it's a little different with the equity issue
that you mentioned in this case because you want to make sure
that to a certain degree of confidence
your system is performing at an acceptable crowding level.
The variability to demand could actually
relate to bulk arrivals or group arrivals
that may happen at once due to exchanges
from different service.
Or it could actually relate to the variability in the headway
or variability in the nature of demand based on day of week,
based on seasonality, based on the weather condition,
and so on and so forth.
Then the other objective in the guideline of TransLink
is the objective of comfort.
And it basically deals, again, with the crowding level
or the design crowding level or crowding averages
that we are basically computing as objectives to be
tested for this guideline.
As you can see again, for different peak
periods and different type of vehicles and type of service,
there is published numbers in terms of the averages
or computed averages for the maximum crowding levels.
So look at these numbers.
Does anyone have any idea of why some of these numbers
are larger?
For example, for peak 15 minutes in AM and PM peak,
you would allow an average of 60 passengers on-board.
However, when it comes to computations of peak
30 minutes, you would only allow 55.
AUDIENCE: You don't want people to be left behind because
of frequency of the services.
Knowing that there maybe another hour or service
is another five minutes.
NEEMA NASSIR: Right, yeah, that could
be one reason that actually yielded to this design.
Any other thoughts or suggestions?
AUDIENCE: Yeah, the 15 minute peaking limit
allows you to have one very full vehicle that
sort of would skew the averages [INAUDIBLE]
and could moderate that.
NEEMA NASSIR: Yeah.
AUDIENCE: [INAUDIBLE]
NEEMA NASSIR: Yeah, exactly.
Yeah, please.
AUDIENCE: Is this like--
could be, like, a chicken or egg problem
where the ones the routes were needed with peak 15 minute
headway are ones that you will expect a lot of people.
Or is it the other way around where you see a lot of people,
and then you make it [INAUDIBLE]..
NEEMA NASSIR: Yes, right.
Well, yeah, that's exactly one of the considerations
in design of a frequency and design of a schedule.
So if I want to reward--
what Ari mentioned-- if you're computing your average over 15
minutes and then you're computing your average over 13
minutes and you're observing a higher crowding level over
the accepted level, then if the situation becomes more
critical--
if you're computing over 30 minutes,
it's more critical than if you're
computing over 15 minutes.
So if you observe an average of high crowding
level for 30 minutes or for a longer period,
that is a sign of a higher actual average
of crowding level.
Yeah.
AUDIENCE: It's funny.
NEEMA NASSIR: Yeah, maybe you explained it better.
I shouldn't have rewarded you.
So the other objective that TransLink covers
is basically the comfort situation.
This is one of the interesting ones.
And I do not really know how it's
possible to measure this for a design.
It's probably usually being used in evaluation of the existing
service.
It basically deals with number of minutes
that you expect from passengers to be standing--
maximum number of minutes of being standing on board.
And there's a level of compliance
that is defined for each one.
For example, you would allow no more than 95% cases
that passengers would have to stand more than 20 minutes
on the trip.
So I can imagine if you have an existing system
and if you want to measure this, you
can go out and survey these numbers
and compute averages and compute the distributions.
However, if you have a design which is not in place,
does anyone have any thoughts how
you can come up with some sort of estimation for this case?
AUDIENCE: [INAUDIBLE]
NEEMA NASSIR: Yeah, simulation could be
one possible way of doing this.
Simulation of demand could be one possible way of doing this.
AUDIENCE: You could check, like, if it's a train--
I saw the Sky Train there, you can see where the train fills
up and then assume that everyone else--
everyone that boards the train afterwards--
if you know how many people are boarding-- if you have--
NEEMA NASSIR: Right.
AUDIENCE: --data to do that, then you
can assume that everyone who's boarding after is standing.
And then you can see how many of them have 20 minutes or more
left on the journey till the train [INAUDIBLE]
NEEMA NASSIR: Exactly.
That's a good idea.
So what you're suggesting is to generate the load profile
for the line.
And whenever the load is over the seating capacity,
you measure the time period on that.
So that's a good idea.
Right.
So in terms of for Toronto Transit Commission,
the loading standards is something like this.
For different types of vehicle, you
would allow different averages for your design.
So there is also one interesting point here.
Why do you think for low frequency service
you would allow a lower crowding level or a lower average
ridership?
AUDIENCE: If it was that crowded,
you would want to add frequency to better serve people riding.
NEEMA NASSIR: Right, yeah.
That could be one good answer.
The other reason that I can imagine
is that if it's a low frequency service
and if someone is denied boarding to a low frequency
service, they have to wait longer.
So we would allow a little bit of a slackness in the design,
so we would avoid a situation like that.
OK, so let's stop here.
And then we will continue through the rest
of the guidelines, particularly with reliability of service
next week.
AUDIENCE: So there's a question there?
NEEMA NASSIR: Right.
AUDIENCE: I was going to ask is there a reason why we
use so many Canadian transits?
NEEMA NASSIR: Sorry?
AUDIENCE: Is there a reason why we
use so many Canadian transits?
NEEMA NASSIR: That's a good question.
AUDIENCE: Their public transportation is better.
NEEMA NASSIR: Yeah, better-- probably the closest place
that has better public transportation.
[LAUGHTER]
AUDIENCE: [LAUGHTER]