Reducing the Hazard of
Losing Balance While
Standing in TTC Vehicles
Request for Proposal
ESC102 - Praxis II
ESC 102 – Request for Proposal
Reducing the Hazard of Losing Balance While Standing in TTC Vehicles 1
Reducing the Hazard of Losing Balance
While Standing in TTC Vehicles
Abstract
On TTC vehicles there is a high risk of losing balance while standing and thereby sustaining injuries. The
majority of injuries on these vehicles are not due to collisions - they occur because of the high levels of
acceleration and deceleration that the vehicles regularly experience [1]. The threshold acceleration level
that a passenger can sustain is often exceeded [2], and passengers can be destabilized if sufficient aids for
support are not available, as is the case when boarding the vehicle.
The problem is amplified by the fact that the interiors of the vehicles are poorly designed to reduce the
severity of injuries once a passenger has lost balance and fallen. Seats are arranged in such a way that a
person could hit them and be severely injured when falling, with the severity of injuries depending on the
position of the passenger in the vehicle [3].
Three potential approaches to addressing the problem have been identified while taking into account the
considerations of stakeholders, such as the community of standing commuters and TTC Administration.
The solution could attempt to prevent the initial loss of balance, to improve the probability of balance
recovery, or to reduce the severity of injury received.
[1] A. Kirk et al., “Passenger casualties in non-collision incidents on buses and coaches in Great Britain,”
in Proceedings of the 18th International Technical Conference on the Enhanced Safety of Vehicles,
Nagoya, Conf. 2003, pp. 1 - 10.
[2] B. De Graaf and W. Van Weperen, (1997). The retention of balance: An exploratory study into the
limits of acceleration the human body can withstand without losing equilibrium, Human Factors, 39 (1),
pp. 111-118.
[3] A. Palacio et al., “Non-collision injuries in urban buses - Strategies for prevention,” Electron. Trinity
College, Dublin, Ireland, Rep. 2009
ESC 102 – Request for Proposal
Reducing the Hazard of Losing Balance While Standing in TTC Vehicles 2
Table of Contents
Section 1 - Introduction ............................................................................................................................. 4
Section 2 – Identifying the Community and their Needs .......................................................................... 4
2.1 The Community of Standing TTC Commuters ............................................................................... 4
2.2 Size of the Community .................................................................................................................... 4
2.3 Needs and Quality of Life of Standing Commuters......................................................................... 5
Section 3 – Problem Definition ................................................................................................................. 5
3.1 Problem Statement ........................................................................................................................... 5
3.2 Validating the Problem .................................................................................................................... 6
3.3 Relation to Quality of Life ............................................................................................................... 6
Section 4 – Scientific Analysis of Balance................................................................................................ 7
4.1 Defining Balance ............................................................................................................................. 7
4.2 Loss of Balance on Transit Vehicles ............................................................................................... 7
4.3 Human Reaction to Balance Loss .................................................................................................... 9
Section 5 – Causes of Injury...................................................................................................................... 9
5.1 Positions of Injured Passengers ....................................................................................................... 9
5.2 Computer Simulations of Injuries .................................................................................................. 10
Section 6 – Stakeholders ......................................................................................................................... 11
6.1 TTC Commuters ............................................................................................................................ 11
6.2 TTC Administrators ....................................................................................................................... 12
6.3 TTC Vehicle Operators .................................................................................................................. 12
6.4 Municipal and Provincial Governments ........................................................................................ 12
Section 7 – Engineering Framing ............................................................................................................ 12
7.1 Objectives ...................................................................................................................................... 13
7.2 Constraints ..................................................................................................................................... 13
7.3 Criteria ........................................................................................................................................... 13
Section 8 – Reference Designs and Design Space .................................................................................. 15
8.1 Potential Design Space .................................................................................................................. 15
8.2 Grooved Handgrip ......................................................................................................................... 15
8.3 Floor Materials and Floor Treads .................................................................................................. 16
Section 9 - Conclusion ............................................................................................................................ 16
ESC 102 – Request for Proposal
Reducing the Hazard of Losing Balance While Standing in TTC Vehicles 3
Appendix A – Breakdown of Weekday TTC Ridership ......................................................................... 17
Appendix B – Maslow’s Hierarchy of Needs .......................................................................................... 18
Appendix C – Empirical TTC Vehicle Acceleration Data ...................................................................... 19
Appendix D – Interviews with the Community ...................................................................................... 23
References ............................................................................................................................................... 25
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Reducing the Hazard of Losing Balance While Standing in TTC Vehicles 4
Section 1 - Introduction
Standing passengers on TTC vehicles are consistently at a risk of losing balance due to high accelerations.
The resulting falls can lead to severe injuries, which directly impairs the quality of life of commuters. The
purpose of this request for proposal (RFP) is to solicit solutions to reducing the hazard associated with
loss of balance. This RFP begins by identifying the community, their needs, and the relation of the
problem to their quality of life. It then addresses their needs by defining the problem thoroughly and
examining its key factors. Finally, some reference designs and design guidelines are provided to help the
designing team.
Section 2 – Identifying the Community and their Needs
This section will provide formal definitions of the key terms in this RFP - community, quality of life, and
need, followed by an idea of the magnitude of the community that the problem affects.
2.1 The Community of Standing TTC Commuters
For the purposes of this RFP, a community is defined as a group of people who share a common aspect of
their lives and interact with one another [1]. This document focuses on the community of standing TTC
commuters. In general, all standing commuters share the experience of travelling from point A to point B
and inevitably interact with each other. Thus, standing commuters can be considered as a legitimate
community. Additionally, the existence of commuter organizations such as TTCriders and Rocket Riders
that voice out the opinion of commuters, including standing commuters, justify the existence of the
community [2] [3]. Furthermore, the TTC has a Customer Liaison Panel and holds Town Hall Meetings
about three times per year with the public, showing how important the commuters are to them [4] [5].
Standing commuters make up a large portion of the community of commuters, as any commuter capable
of standing could potentially be a standing commuter.
2.2 Size of the Community
On their respective planned capacities, 25% of people are standing on a bus, 38% are standing on a
streetcar, and 63% are standing on a subway car [6], as shown in Table 1.
Table 1 - Planned capacity of TTC Buses, Streetcars, and Toronto Rocket [6]
Bus Streetcar Toronto Rocket
Capacity 48 74 180
Seated 36 46 66
Standing 12 28 114
% Standing 25% 38% 63%
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The TTC reports that passenger demand during AM peak hours is near or over its capacity with AM peak
hours defined to be from the start of service until 8:59 AM on weekdays [7] [8]. A similar demand can be
assumed in the PM peak hours that are defined to be from 3:00 PM to 6:59 PM on weekdays [8]. Thus, it
can be safely assumed that the percentage of people standing during peak hours is near or above the
planned capacities. The number of standing commuters during the non-peak hours is considered to be
minimal. Clearly, this is a large and justified community. To put this into perspective, according to
statistics published by the TTC, approximately 1.6 million customers were served per weekday in 2011
[6]. Using the ratio of peak to off-peak riders and passengers in each vehicle type, it can be deduced that
there are 700,000 riders during the peak hours, of which somewhere between 288,040 and 436,000 have
to stand during their trip [6] [9] (See Appendix A for a breakdown of daily ridership). This is around 18 -
27% of the total number of TTC customers. However, as previously discussed, any commuter that can
stand is potentially a standing commuter, and so the size of the community can easily extend to almost all
of the 1.6 million daily TTC commuters.
2.3 Needs and Quality of Life of Standing Commuters
As the definitions of quality of life and need can be ambiguous, these two terms are defined next. Need is
defined as an aspect of life, physical or otherwise, that one finds or would find desirable or fundamental
to their day-to-day activities and interactions, and quality of life has been defined as the extent to which
needs are fulfilled. With this in mind, a need experienced by the community of standing TTC commuters
is identified as the reduction and prevention of loss-of-balance related injuries. Their quality of life is
reduced if there is high hazard of loss-of-balance injuries and if they do sustain injuries due to loss of
balance. This is discussed in more detail in the next section.
Section 3 – Problem Definition
This section first describes the specific problem that this RFP attempts to address. Then the classification
of the problem as a need will be justified and finally, the link between the stated problem and one’s
quality of life will be addressed and explored.
3.1 Problem Statement
Standing commuters are consistently at risk of losing balance due to the start-stop nature of public
transportation. As public transit vehicles of all types must stop at predetermined stations and curbside
stops, the passengers inside are subjected to forces resulting from both the vehicle’s acceleration and
deceleration. During both acceleration and deceleration, there is a risk of passengers losing balance,
which in turn creates a risk of injury. The severity of injuries can vary from minor sprains and fractures
to, in extreme cases, death [10]. In a personal interview with Jeff Raphael of Raphael Barristers, a law
firm that focuses on personal injury law and insurance claims [11], he stated that the injuries suffered by
those who file lawsuits against the TTC vary from soft tissue injuries such as bumps and bruises to
concussions and broken bones [12].
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3.2 Validating the Problem
While collision injuries generally receive more attention than non-collision injuries due to the increased
severity, 2010 data from the United States showed that non-collision incidents occur four times more
frequently than collision incidents, with 20 007 non-collision incidents compared to 4209 collision
incidents [13]. Past studies have shown that during these incidents, it is the standing passenger that is the
most at risk [14]. During a personal interview, Jeff Raphael stated that in his experience, injuries on TTC
vehicles occur when a bus is cut-off by a car and the driver must “slam on the brakes”, causing the
passengers to “go flying” [12], which supports the claim that standing passengers are at a higher risk of
injury.
This claim is further validated by a British study conducted in 2003, which showed that the largest
portion of serious injuries occurred to standing commuters while boarding, exiting, or just standing on the
vehicle [10] (see Figure 1). The boarding and exiting numbers include not only falls that occur while
leaving the vehicle, but also those that occur while moving to leave the vehicle. The large number of these
incidents while standing relative to those while seated sufficiently shows the severity of the problem.
Figure 1 - Portions of injuries in each group that are considered KSI (killed or serious injuries) [10]
Extreme braking problems have also occurred on the TTC. In May 2012, when a Route 6 (Bay) bus
travelling southbound on Bay Street braked suddenly, eleven people were taken to hospital for complaints
of back and neck pain, of which nine were treated for minor injuries [15].
3.3 Relation to Quality of Life
Studies found that during non-collision events, “the most injured segment is the head (between 23% and
33% of the injuries), followed by the upper limbs (between 20% and 28%) and the lower limbs (between
18% and 21%)” [14]. If we consider Maslow’s hierarchy of needs, where safety is the second most
fundamental level of needs (see Appendix B), and our previously provided definition of quality of life,
one can see that safety of standing passengers directly affects their quality of life [16]. Referring to the
previous definition of “need”, it is reasonable to say that good health is an aspect of life that the majority
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of the community would find desirable and as such, a person’s physical health has an effect on his or her
quality of life.
Section 4 – Scientific Analysis of Balance
In order to be able to properly understand the hazard associated with balance, background information
will be presented, including the definition of balance, how passengers lose balance on transit vehicles, and
how they react to this initial loss.
4.1 Defining Balance
As this project deals with standing
commuters, the term standing stability will
be considered analogous to balance.
Standing stability in static situations is
defined such “that the vertical projection of
the centre of mass (COM) should be within
the base of support (BOS)” [17]. This is
illustrated in Figure 2.
4.2 Loss of Balance on Transit Vehicles
One of the main causes of falls on transport vehicles worldwide is the lower acceleration threshold that a
human can withstand without the aid of a support. A Dutch study conducted in 1997 by De Greef and
Van Weperen [19], whose purpose was to confirm a previous study in 1942 [20], verified the acceleration
levels an unsupported human can withstand when standing with a normal posture. This study also found
that the acceleration a human can withstand is doubled with the aid of a handlebar [19]. The acceleration
threshold values are summarized in Table 2. This data suggests that a strong support infrastructure inside
a vehicle greatly aids in maintaining balance.
Table 2 - Acceleration thresholds for losing balance for humans with and without
support [19]
Acceleration
Condition
Forward
Acceleration
Backward
Acceleration
Lateral
Acceleration
Supported
Acceleration
Threshold 0.54 m/s2
0.61 m/s2
0.45 m/s2
1.50 m/s2
Figure 2 – Visual representation of balance as
defined by the COM projected over the BOS. The
situation to the right shows the loss of balance that
occurs when the vertical projection of the COM no
longer lies within the BOS. [18]
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The same study also found that Dutch transportation vehicles easily exceeded these acceleration levels.
To confirm that these levels are still present in current vehicles and specifically those in use by the TTC,
our team recorded the acceleration levels on a daily commute in both bus and subway using smartphone
accelerometers. From these recordings, it was found that the threshold for supported passengers was
exceeded by both vehicles (see Table 3).
Table 3 - Number of times the supported acceleration threshold for losing balance is surpassed in three
TTC Routes, measured using a smartphone accelerometer.
Route Vehicle
Stops
Time
(minutes)
Lateral
Threshold
Occurrences
Longitudinal
Threshold
Occurrences
Bloor-Danforth Subway
(Islington to St. George Station) 14 20 1 9
University-Spadina Subway
(St. George to Queen's Park Station) 2 5 0 2
Bus Route 37A – Islington
(Woodbine/Hwy 27 to Islington
Station)
N/A 30 203 6
As seen in the recorded data, all three routes exceeded the increased acceleration threshold. While the bus
route does so most frequently, it should be noted that buses make more frequent turns, which causes the
increase in lateral acceleration (see Appendix C for more complete data). Although acceleration levels
above the supported threshold were much less frequent than those above the unsupported threshold (see
Appendix C), the data shows that supports can aid in reducing balance loss but do not guarantee that
balance loss will never occur.
It is important to note that there are scenarios that these results do not account for, namely, the scenarios
in which drivers are forced to accelerate or decelerate rapidly in order to avoid collision. This data was
collected on rides in which no emergency stopping occurred. These emergency stops would increase the
number of occurrences of above-threshold acceleration, thereby increasing the associated hazard.
The issue of lacking support is most prominent when the vehicle is loading and unloading. Vehicles often
accelerate after loading while passengers who just boarded are still moving towards their seat or area of
support. Moreover, passengers tend to stand and move towards the exit while the vehicle is decelerating
to a stop prior to unloading due to pressure to reach the doors in time. This increases the risk of an initial
fall due to lack of support. This claim is evidenced by the data shown in Figure 1 in Section 3.2, where
passengers entering and exiting the vehicle receive serious injuries at a higher rate than those standing and
seated [10].
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4.3 Human Reaction to Balance Loss
In the scenario that loss of balance is lost, two types of reactions can occur: fixed support reactions and
change of support reactions [21]. Fixed support reactions center on the reaction in the hip, knee, and ankle
joints, and as such, fall out of the scope of expectations for this project [22]. On the other hand, change of
support strategies generally fall under two categories: upper limb (arm movements), and lower limb (foot
and leg movement) [21]. This can be addressed directly through TTC-related projects. While this narrows
down the scope of potential solutions, change of support reactions occur widely in loss of balance
scenarios, with data showing that “compensatory stepping evident in 32% to 45% of falls or near-falls and
arm movements evident in 65% to 72% of these incidents” [23].
When a person takes a step forward in attempt to regain balance, the coefficient of friction of the flooring
material plays an important role in the success of this maneuver. The United States Occupational Safety
and Health Administration recommends that the floor-shoe interface have coefficient of static friction of
at least 0.5 for walking [24]. For certain activities where loss of balance a more pressing problem, such as
lift platforms and ramps, a greater coefficient of 0.6-0.8 is recommended [25]. Thus, the coefficient of
friction must be sufficiently large so as to grasp the floor firmly when taking a step to recover balance.
The coefficient cannot be too large, however, as a coefficient as large as 1.0 could cause a person’s shoes
to catch on the floor and result in tripping.
Section 5 – Causes of Injury
This section will examine the exact mechanism of passenger injuries on public transportation vehicles
with regard to the relationship between the positions of passengers and injury type. The section is based
on a two studies conducted on the subject: a study in Great Britain which gathered data on approximately
27 000 incidents from 1999 to 2001 [10], and a 2008 study in Dublin, Ireland which discussed the source
of injury in more depth [14].
Although these studies were concerned exclusively with buses in the U.K, their results should be
applicable to TTC vehicles, including subways and streetcars. TTC vehicles have similar seating
arrangements and balance aids, and they experience similar acceleration levels. Therefore, it is reasonable
to expect that injuries due to loss of balance occur in the same manner on TTC vehicles.
5.1 Positions of Injured Passengers
First, the study in Great Britain investigated the positions of the injured passengers during the incidents.
The study determined that 56.4% of serious injuries occur to passengers who are not seated. This is
particularly significant considering that less than 20% of passengers on buses in London are standing
[26][27], which means that the standing passengers are overrepresented. The same study also determined
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the portion of the injuries that are considered fatal or serious for passengers in each position, which is
shown in Figure 1 in Section 3.2. It is interesting to note that more injuries occur to alighting passengers
than to boarding passengers. This could in part be explained by the fact that drivers tend to be more aware
of the boarding passengers, but a more probable cause is that humans have a greater risk of losing balance
when standing suddenly after being seated for an extended period of time [28].
It is also important to consider the positions that bus passengers occupy. Figure 3 depicts the most
common standing positions on buses, which the study in Dublin determined by observing standing
passengers on buses. Passengers are most likely to be standing to the side of a bus holding a horizontal
bar above the head (position 1) or standing in the centre and holding a vertical pole in front of them
(position 2).
Figure 3 - The most common standing positions of commuters on the bus [14]
5.2 Computer Simulations of Injuries
Taking into account the bus acceleration, positions of passengers, and coefficient of friction, the Dublin
study simulated the falls of passengers with computer programs to determine the most severe hazards on
buses. Figure 4 illustrates the sequence of steps leading to injury when a passenger in position 1 (in
Figure 3) falls as the bus accelerates from rest to a constant velocity.
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Figure 4 - Computer simulation of fall due to bus acceleration [14]
When the coefficient of friction in the simulation was set to 0.49, a low value, the passenger’s head struck
the handle on the seat in front with a 35% probability of skull fracture. The passenger’s leg also suffered
from a high bending torque near the threshold value due to contact with the front of the seat. However,
when the simulation was repeated with a larger coefficient of friction of 0.85 there was no contact at all
between the head and the seat handle [14].
Simulations were also done with the passenger in position 2 (in Figure 3). In this position, the passenger
fell over backwards and fractured their knee 35% of the time, but suffered no head injuries. As a whole,
injuries were greatly reduced, as position 2 is a designated area for standing with relatively few objects
nearby that could cause injury if hit. However, the hard impact with the floor can still cause hip injuries,
and so more restraints to prevent falls are required [14].
Section 6 – Stakeholders
The stakeholders that must be considered for this project are the following: TTC commuters, TTC
administration, TTC vehicle operators, government, and manufacturers. The stake and importance of each
stakeholder is explained in this section.
6.1 TTC Commuters
TTC commuters would want to be safe and comfortable during their trip, as security of both safety and
comfort, as previously stated, falls under a need. As such, this product is expected to fulfill these needs.
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A representative from the TTCRiders organization also suggests that one of the most important needs of
TTC commuters is an affordable transit system [29]. This is due to the fact that the vast majority of the
TTC’s operating budget stems from user collected revenue [30]. Any potential product would need to be
cheap, as fare hikes often leave potential commuters unsatisfied with the service, as seen in a 2009
Toronto Star article [31] and a BlogTO poll [32]. While these sources do not gather information from a
large enough sample size to be considered representative of the community, the general negative trend
expressed shows that fare increases are a genuine concern to the community.
While these needs apply to all TTC commuters, the need for both balance and comfort is more pressing
for standing commuters due to the increased risk for injury associated with standing.
6.2 TTC Administrators
The TTC is committed to the safety of its customers, as the issue of perceived safety on TTC vehicles
influences their budget. This is evident in research conducted by UCLA’s department of urban planning,
where it was found that system safety had a greater impact on ridership than fare cost [33]. Furthermore,
injuries on the TTC can lead to expensive lawsuits, especially considering a recent change to the
Insurance Act that prevents those who are injured in motor accidents from claiming insurance benefits if
there is no collision [34][12]. This leaves the injured with filing a lawsuit as the only method of receiving
compensation [12]. Therefore, it is in the TTC’s interest to prevent customers from falling and sustaining
injuries.
6.3 TTC Vehicle Operators
TTC vehicle operators can be held responsible for falls or injuries that a passenger might sustain due to
rapid accelerations or decelerations [15][12]. As such, they would want to prevent such incidents from
happening.
6.4 Municipal and Provincial Governments
As a company, the TTC has only two sources of funding - collected fares and subsidies [30]. As such, any
required increase in TTC funding to implement a potential solution without fare increases would need to
meet government approval.
Section 7 – Engineering Framing
The problem of losing balance and consequently injuring a person is a problem of engineering design.
Engineering design can be defined as the application of engineering principles in a creative and usually
iterative way to create a solution for a problem [35]. Specifically, the problem posed in this RFP requires
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Reducing the Hazard of Losing Balance While Standing in TTC Vehicles 13
an intervention to prevent people from losing balance and falling and/or preventing injury from falling.
As such, we have defined the following objectives, constraints, and criteria for the development of a
potential solution.
7.1 Objectives
The solution must reduce the hazard associated with losing balance on TTC vehicles. This high-level
objective can be broken down into three components:
Initial balance loss: by reducing the probability of losing balance, the issue of related injuries is
mitigated.
Success of change in support strategies: by increasing the success of change in support strategies,
one can mitigate balance-related injuries without affecting initial balance loss.
Severity of injuries: given that a fall has occurred, the hazard can still be decreased by reducing
the severity of injuries that a TTC passenger could sustain.
7.2 Constraints
The solution must:
maintain the current passenger capacity of TTC vehicles. The TTC states that their goal is “to
provide the safest, highest-quality public transportation in the world” [36]. If we consider high-
quality transit as providing efficient transportation for passengers, then lowering the passenger
capacity is contrary to their goal. Passengers also wish to travel as efficiently as possible, and
reducing the passenger capacity restricts their movement.
allow riders to enter and exit the vehicle with ease. Impeding the ability to enter and exit from
vehicles causes delays, which contradicts the goal stated above.
NOT increase the frequency of non-balance related injuries. Doing so would be
counterproductive to the considered community of standing commuters, who value their safety.
NOT require regular maintenance. Regular maintenance results in increased operating costs
incurred by the TTC, which is contrary to their stake in the problem.
7.3 Criteria
The following are criteria upon which the solution will be judged:
The number of body types that can use the solution (metric: percentage of varying physiques that
are aided by the solution, where greater is better).
The solution should have the greatest impact possible on the community, and having a solution
that improves the quality of life of members of the community who vary physically accomplishes
this task. As the objective of the solution is to reduce the hazard associated with balance, the
hazard for the population as a whole is reduced by affecting a larger portion of the population.
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To aid in this criteria, our team has provided a set of fifth and ninety-fifth percentile adult
statistics, collected by the United States Military for human factors engineering and also
presented in BodySpace: Anthropometry, Ergonomics, and the Design of Work, that should be
considered in trying to make the solution as far-reaching as possible (Table 4).
Table 4 - Fifth and ninety-fifth percentile statistics of adult anthropometry (ages 19-65) [37][38]
Statistic Percentile Male Female
Comfortable Reaching Length (shoulders,
in mm) 5
th 610 555
Maximum Reaching Length (shoulder to
fingers, rotated body in mm) 5
th 842 735
Total Vertical Body Span (from fingers of
arms extended overhead to feet, in mm) 5
th 2004 1853
Stature (Height, in mm) 5th 1640 1520
Stature (Height, in mm) 95th 1870 1730
The number of different vehicle types that the solution applies to (metric: number of different
vehicles affected, where more is better).
The community of standing commuters is not restricted to any one specific vehicle used in public,
and as such, designing to implement the solution on one specific vehicle ignores a vast majority
of the community. By incorporating a larger portion of the community with the solution, the
hazard for the community as a whole is lowered. For example, the TTC operates light rail, heavy
rail, streetcars, and buses, and within each of these categories, multiple vehicle types are also
present. [6]
The amount of time required to implement the solution (metric: time spent, where less is better).
The longer a solution takes to implement, the longer the passenger is at risk of injury,
contradicting the main objective of the solution. The time spent also affects the cost of the
solution, which is important to almost all the primary stakeholders of the project.
Cost of the solution (metric: amount of money required to implement the solution plus any
maintenance cost that will potentially be incurred; less is better).
After a certain threshold, the cost of the solution may outweigh the risk of injury. The TTC only
receives a certain amount of funding from governments and will usually turn to increasing fares
to compensate for budget shortfalls, which is contrary to the stake of TTC commuters and
administration.
A recommended method to accomplish these criteria is to design a solution that could be retrofitted in
existing TTC vehicles, if applicable. This would help minimize both the cost and the difficulty of
implementation.
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Reducing the Hazard of Losing Balance While Standing in TTC Vehicles 15
Section 8 – Reference Designs and Design Space
This section considers the design space of the potential solution, while providing reference designs to
exemplify a few of the possible directions. Note, however, that these designs are not meant to frame the
potential solution and are only provided to show the divergent nature of the problem.
8.1 Potential Design Space
As the nature of the problem is inherently divergent, many different aspects may be addressed while still
adhering to the objective of the solution. The SAFEBUS project, an initiative by engineers at the Instituto
de Biomecánica de Valencia and other institutions, highlights numerous areas for potential improvement.
Among these are the organization of the interior, the ability to enter and exit the vehicle, and the
accessibility of supports such as handles. Design teams may refer to this work for guidance, but again,
need not be limited by it. [39]
While the operators of vehicles are the direct cause of acceleration, approaching the problem from this
perspective is not recommended. It is impossible to eliminate scenarios in which drivers are forced to
accelerate or decelerate rapidly, and thusly incredibly difficult to reduce the frequency of balance loss.
Vehicle operators are required to both accelerate and decelerate rapidly to avoid collisions, which
ultimately increase the safety of passengers as a whole.
8.2 Grooved Handgrip
The grooved handgrip, found in the patent shown in
Figure 5 (right), addresses the issue of reducing the
occurrence of balance loss. This is done through the use
of grooving, which is meant to improve the interface
strength between the human hand and the handlebar. The
grip also boasts a plastic coating, another effort to
decrease the amount of force required to maintain
balance by increasing the coefficient of friction between
the user’s hand and the grip.
While this solution addresses the issue of reducing initial
balance loss, it fails to encompass a large amount of the
population, as the issue only addresses those who can
successfully reach the bars in the first place [40]. The
grip also assumes that the hand is properly orientated on
the bar, as it provides no extra benefits if the hand cannot
fit into the grooves.
Figure 5 - Grooved handgrip system [40]
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8.3 Floor Materials and Floor Treads
Some companies such as Altro, Gerflor and Koroseal Matting
provide various flooring solutions in transit vehicles to
increase slip resistance and traction [41] [42] [43]. These
flooring materials have greater slip resistance, especially
when the floor is wet. In addition, Koroseal installs pebble
treads and ribbed step treads that “provides exceptional
traction and improved drainage” (see Figure 6) [44]. While
these solutions help passengers regain balance after losing it,
they do not fully reduce the hazard of sustaining injuries in
case a person falls.
Section 9 - Conclusion
Commuters that are forced to stand during transit are inherently faced with a more significant hazard. The
issue of attempting to reduce the hazard associated with loss of balance is naturally divergent due to the
nature of the hazard itself. As such, any solution could potentially deal with the varying spectrum
associated with this hazard, be it reducing the chance of initially falling, improving the probability of
recovering balance, or reducing the severity of injury after the initial fall. In creating these solutions, one
must account for the stakeholders and the relationship that they hold with the solution, keeping in mind
the constraints and criteria.
Figure 6 - Pebble Treads from Koroseal
Matting to improve traction and drainage
[44]
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Reducing the Hazard of Losing Balance While Standing in TTC Vehicles 17
Appendix A – Breakdown of Weekday TTC Ridership
This appendix contains a summary of the number of people who have to stand while riding the TTC. This
subset of the community of TTC commuters has the most needs, as described in Section 2.2.
Percentage of Annual Ridership in Peak Hours: 219000 / (219000 + 282000) = 43.7% [9]
Appendix Table 1 – A breakdown of the average number of TTC passengers during peak hours, on different
types of vehicles, with an emphasis on those who are standing [6][9]
Daily Revenue
Passengers
Daily Revenue
Passengers in Peak
Hours
% Standing in
Planned Capacity
Standing
Passengers
Bus 706,000 309,000 25% 77,250
Streetcar 288,000 126,000 38% 47,880
Subway 588,000 257,000 63% 162,910
Total 1,582,000 692,000 288,040
However, the numbers presented above are revenue passengers only and do not include the passengers
that transfer between routes. The actual number people who have to stand during their trip could be as
high as 63% of the total number of passengers during peak hours, which is 436,000 assuming all
passengers take the subway.
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Reducing the Hazard of Losing Balance While Standing in TTC Vehicles 18
Appendix B – Maslow’s Hierarchy of Needs
A visual representation of Maslow’s theories about human needs, mentioned in Section 2.3, as published
in his paper in 1943:
According to Maslow, people need safety when their physiological needs are satisfied.
Appendix Figure 1 – Maslow's Hierarchy of Needs [45]
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Reducing the Hazard of Losing Balance While Standing in TTC Vehicles 19
Appendix C – Empirical TTC Vehicle Acceleration Data
A BMA150 accelerometer from Bosch Sensortec GmbH installed in a Sony Ericsson Xperia pro
smartphone was used to measure the lateral and longitudinal acceleration of TTC vehicles. The
accelerometer has a range of 2 g or 19.6 m/s2 and a resolution of 4 mg or 0.04 m/s
2 [46].The
Accelerometer Monitor app created by Mobile Tools was used to gather the data.
The smartphone was held horizontally face-up and as stable as possible during the duration of the
experiments. Lateral and longitudinal acceleration were measured every 60 milliseconds (for a sampling
rate of 16 Hz). Note that due to the unsophisticated devices and random errors, these data have an error of
0.2 m/s2. The three routes on which experimental data were collected are the Route 37A (Islington) Bus
from Woodbine and Hwy 27 to Islington Station, the Bloor-Danforth Subway from Islington to St.
George Station, and the University-Spadina Subway from St. George to Queen’s Park Station.
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Reducing the Hazard of Losing Balance While Standing in TTC Vehicles 20
C.1 Acceleration Data from a Route 37A (Islington) Bus from Woodbine/Hwy 27 to Islington
Station, taken on February 13, 2013, approximately from 11:00 AM to 11:30 AM
Appendix Figure 2 - (a) Lateral and (b) Longitudinal Acceleration in a Route 37A (Islington)
Bus from Woodbine and Hwy 27 to Islington Station.
a)
b)
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Reducing the Hazard of Losing Balance While Standing in TTC Vehicles 21
C.2 Acceleration Data from a Bloor-Danforth Subway Car from Islington to St. George Station,
taken on February 13, 2013, approximately from 11:35 AM to 12:00 PM
Appendix Figure 3 - (a) Lateral and (b) Longitudinal Acceleration in a Bloor-Danforth Subway
Car from Islington to St. George Station.
a)
b)
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Reducing the Hazard of Losing Balance While Standing in TTC Vehicles 22
C.3 Acceleration Data from a University-Spadina Subway Car from St. George to Queen’s Park
Station, taken on February 13, 2013, approximately from 12:05 PM to 12:10 PM
Appendix Figure 4 - (a) Lateral and (b) Longitudinal Acceleration in a University-Spadina
Subway Car from St. George to Queen’s Park Station.
a)
b)
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Reducing the Hazard of Losing Balance While Standing in TTC Vehicles 23
Appendix D – Interviews with the Community
D.1 - Personal Interview with Jeff Raphael, Personal Injury Lawyer
A phone interview with Jeff Raphael of Raphael Barristers, a law firm that deals with injury claims
against the TTC was conducted on February 14, 2013 and a summary of the interview is presented below.
He has experience representing plaintiffs who wish to sue the TTC because of injuries from riding the
TTC. He helped us confirm the existence of the problem and provided us with some idea of the
frequency of non-collision injuries on the TTC. The latter was of particular help to us, as the TTC does
not publicize statistics regarding injuries.
1. How frequently do you receive cases regarding non-collision injuries involving TTC vehicles? Do
you have an idea about the total number of such cases annually?
Cases regarding non-injury collision injuries involving TTC vehicles tend to come up 2-4 times a year for
Mr. Raphael, however the number varies.
2. Generally what kinds of injuries are experienced by the plaintiffs?
The type of injury varies- in his experience plaintiffs have experienced soft tissue injuries such as bumps
and bruises, head injuries such as concussions, and broken bones.
3. What tends to be the severity of the injuries experienced by the plaintiffs?
The severity of injuries tends to vary (as described above).
4. In most cases, who is found to be at fault?
It's tough to say who exactly is at fault with non-collision injuries. Mr. Raphael has seen cases where the
bus is cut-off and the driver slams on the brakes, resulting in the passengers going flying. In these cases,
the person at fault could be the unknown driver of the car, the driver who over reacted or both.
5. In your experience, has the plaintiff ever lost their case and if yes why?
The outcomes of cases vary. As the plaintiff, the burden of proof is on him or her to prove negligence on
the part of the driver or the TTC. Recently (May 12, 2011), the insurance act was amended so that now if
someone is injured in a motor vehicle but there is no collision, they can no longer claim accident benefits
from their insurance company to cover things such as medical expenses, only leaving them the option of
suing.
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Reducing the Hazard of Losing Balance While Standing in TTC Vehicles 24
D.2 - Personal Email with Dr. Franz Hartmann, Representative of the TTCriders advocacy
group
Dr. Hartmann was listed as the primary contact of the TTCriders, an advocacy group which is
dedicated to maximize the responsiveness of the TTC and improve the TTC in terms of
providing an effective and affordable service. Although he did not comment on the issue of non-
collision injuries on TTC vehicles, he stressed that an affordable system is a priority for many
TTC riders.
Sent Feb 13, 2013 - 11:37
Hello Mr. Hartmann,
My name is Patrick Loa and I am a first year Engineering Science student at the University of
Toronto. This semester in our design course, we were given the task of improving the quality of life of a
community in need in the city of Toronto, with the focus of my group being the prevention of loss of
balance related injuries on the TTC. I am emailing you today because I was wondering if you could spare
a few moment of time to answer a few questions pertaining to our project.
1. What are some of the greatest needs of TTC riders?
2. In your opinion, does balance directly relate to the safety of riders while on TTC vehicles?
3. In your opinion, are there ways to help standing riders maintain their balance while on TTC vehicles?
Thank you in advance for your time,
Patrick Loa
Received Feb 13, 2013 - 15:46
Hi Patrick,
Thanks for your email. We are not experts on balance issues on TTC vehicles so cannot comment on
questions 2 and 3. Right now, we argue the greatest need of TTC riders is for an affordable system with
frequent services to all parts of the city.
All the best,
Franz Hartmann, PhD
Executive Director
Toronto Environmental Alliance
416-596-0660
Help us build a greener city for all by donating to TEA:
www.torontoenvironment.org/actioncentre/donate
ESC 102 – Request for Proposal
Reducing the Hazard of Losing Balance While Standing in TTC Vehicles 25
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Reducing the Hazard of Losing Balance While Standing in TTC Vehicles 26
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