Nose to Armpit

23 Aug

I’m always amazed when I travel to other cities and ride their public transportation to observe exactly what is accepted/tolerated as the ‘norm’ for personal space on public transportation. Sure, in larger cities one would expect that personal space would differ from smaller cities or systems. At least I go in with the expectation that my space will be limited to the bare minimum, ‘nose to armpit;’ but why is that?

When I travel, I feel as though I am playing a sociologist-like role as a transportation planner. Like the Jane Goodall of public transportation, I observe the passengers in their natural habitat. I hypothesize to myself: Is this phenomenon regional? Cultural? Is it out of necessity? Are people in larger cities simply more aggressive out of necessity? Are these necessities dictated by elements described by Maslow’s Hierarchy of Needs? Do transit customers in medium or small cities feel more entitled to space than those riders in larger cities solely because the space is available?

So, what exactly is considered an ‘acceptable passenger area’ range for various types of transit modes, passenger scenarios, and loading scenarios? Furthermore, what parameters are used to plan for such for level of service (LOS) expectations? Do transit planners in large systems even realize that I’m standing with my nose in someone’s armpit?!!

A great amount of research, both normative and descriptive, has been conducted in the transit industry to investigate these questions. The following excerpts are from the TCRP Report 100 – Transit Capacity and Quality of Service Manual -2nd Edition (TCQSM):

Transit is typically considered less attractive when passengers must stand for long periods of time, especially when transit vehicles are highly crowded. When passengers must stand, it becomes difficult for them to use their travel time productively, which eliminates a potential advantage of transit over the private automobile. Crowded vehicles also slow down transit operations, as it takes more time for passengers to get on and off, and rail passengers may try to hold doors open in order to squeeze onto the train.

Most transit agencies assess the degree of passenger crowding on a transit vehicle based on the occupancy of the vehicle relative to the number of seats, expressed as a load factor. A factor of 1.0 means that all the seats are occupied. The importance of vehicle loading varies by the type of service. In general, transit provides load factors at or below 1.0 for long-distance commute trips and high-speed mixed-traffic operations. Inner-city rail service may approach 2.0 or even more, while other services will be in between.

Some agencies’ service standards balance service frequencies (i.e. the number of transit units on a given route or line, moving in the same direction, that pass a given point within a specified interval of time; also known as a headway) with passenger loads (i.e. the number of passengers on a transit unit at a specific point). When boarding volumes are relatively low, service frequencies will also be low, to avoid running nearly empty buses, but sufficient buses will be provided to ensure that all passengers can have a seat. At higher boarding volumes, not all passengers will be able to get a seat, but frequencies are set high enough to ensure that passengers will not have to wait long for the next bus (TCQSM, 3-18).


Quality of service reflects the passenger’s perception of transit performance and depends to a great extent on the operating decisions made by a transit system within the constraints of its budget, particularly decisions on where transit service should be provided, how often and how long it is provided, and the kind of service that is provided. Quality of service also measures how successful an agency is in providing service to its customers, which has ridership implications (TCQSM, 3-1).

Levels of Service

The selection of LOS thresholds for each of the service measures presented in this manual represent the collective professional judgment of the TCRP Project A-15A team and panel. However, the LOS ranges—in particular, LOS “F” for fixed-route service are not intended to set national standards. It is left to local transit operators and policy agencies to decide how or whether to describe performance in terms of levels of service. It is also left to local decision-makers to determine which LOS ranges should be considered acceptable, given the unique characteristics of each agency and the community served. To aid in this effort, this manual provides guidance on the changes in service quality perceived by passengers at each LOS threshold.

Level of Service Framework

Fixed-Route Service

Fixed-route quality of service measures into two main categories: (1) availability and (2) comfort and convenience. The availability measures address the spatial and temporal availability of transit service. Assuming, however, that transit service is available, the comfort and convenience measures can be used to evaluate a user’s perception of the quality of his or her transit experience (TCQSM, 3-2).


Different elements of a transit system require different performance measures:

Transit Stops: measures addressing transit availability and comfort and convenience at a single location. Since these measures depend on passenger volumes, scheduling, routing, and stop and station design, performance measure values in this category will tend to vary from one location to another.

Route Segments/Corridors: measures that address availability and comfort and convenience along a portion of a transit route, a roadway, or a set of parallel transportation facilities serving common origins and destinations. These measure values will tend to have less variation over the length of a route segment, regardless of conditions at an individual stop.

Systems: measures of availability and comfort and convenience for more than one transit route operating within a specified area (e.g., a district, city, or metropolitan area). System measures can also address door-to-door travel.

Lower-level measures (e.g., stop-level) are also applicable at higher levels (i.e., the route or system levels). Combining the two performance measure categories with the three transit system elements produces the matrix shown (TCQSM, 3-2).

It should be noted that this entry specifically looks at what is considered acceptable for passenger loads at the stop-level, as that is the typical customer’s point of view.

(TCQSM, 3-3).

Transit System Size Considerations

In measuring transit quality of service, the size of the city, metropolitan area, “commuter-shed,” or transit service area may need to be taken into account. A small city could regard transit service on a route every 30 minutes for 12 hours per day, six days per week to be good. In a large transit system, good service could require service at least every 10 to 15 minutes, 18 hours per day, and seven days per week. However, these determinations of “good service” are based as much on passenger demand and the realities of transit operating costs as they are on passengers’ perceptions of service quality.

The question naturally arises, should there be different levels of service for different sized areas? From purely a passenger’s perspective, which quality of service is based upon, the answer is “no”: a 1-hour headway between buses is just as long for a passenger in a small town as it is for a passenger in a large city. Therefore, no distinction has been made in the levels of service to account for area population. (The consequences of providing a 1-hour headway, though, do vary by city size and are reflected by other measures, such as passenger loads. These consequences will be more severe in a large city than in a small city.)

LOS ranges are not adjusted to reflect differences in city sizes. From an agency’s standpoint, though, there are significant differences between small towns and large cities, particularly in passenger demand volumes and available funding levels. If agencies choose to develop service standards based on levels of service, these will likely vary based on community size: a small city agency might wish to provide a seat for every passenger (LOS “C” or better), while a large city agency might allow maximum schedule loads (LOS “E”) during peak periods. The service measure and the quality perceived by the passenger for a given LOS is the same in both cases (TCQSM, 3-27).



From the passenger’s perspective, passenger loads reflect the comfort level of the on-board vehicle portion of a transit trip—both in terms of being able to find a seat and in overall crowding levels within the vehicle. From a transit operator’s perspective, a poor LOS may indicate the need to increase service frequency or vehicle size in order to reduce crowding and provide a more comfortable ride for passengers. A poor passenger load LOS indicates that dwell times will be longer for a given passenger boarding and alighting demand at a transit stop and, as a result, travel times and service reliability will be negatively affected (TCQSM, 3-43).


Passenger load LOS is based on two measures: load factor (passengers per seat), when all passengers can sit, and standing passenger area, when some passengers must stand or when a vehicle is designed to accommodate more standees than seated passengers. Passenger load LOS can be measured by time of day (e.g., LOS “D” peak, LOS “B” off-peak) or by the amount of time a certain condition occurs (e.g., some passengers must stand for up to 10 minutes).

When a substantial number of passengers wear or carry objects such as daypacks or briefcases, that increase the space occupied by those passengers, analysts may wish to use the concept of equivalent passengers, based on the projected area values given in Exhibit 3-25. For example, a passenger wearing a daypack takes up about twice as much space as a passenger without one. If, on average, 5 of 10 standing passengers wear daypacks, then the space occupied by the standees is the equivalent of 15 unencumbered standing passengers.


The standing passenger area can be measured using a typical vehicle or estimated using the procedure described below. The area next to the vehicle operator, stepwells, interior steps, and wheel wells should not be included as part of the standing area. In addition, a 14-inch (0.36-m) buffer should be left in front of longitudinal seating to account for seated passenger foot room.


When the standing passenger area is not known, it can be estimated as follows:

1. Calculate the gross interior floor area. Multiply the vehicle width by the interior vehicle length. For standard buses, the interior vehicle length can be estimated by subtracting 8.5 feet (2.6 m) from the total bus length, as an allowance for the engine compartment and operator area.

2. Calculate the area occupied by seats and other objects:

• Transverse seating: 5.4 ft2 (0.5 m2) per seat

• Longitudinal seating: 4.3 ft2 (0.4 m2) per seat

• Wheelchair position: 10.0 ft2 (0.95 m2) per position (use when the wheelchair position is not created by fold-up seats)

• Rear door: 8.6 ft2 (0.8 m2) per door channel

• Interior aisle stairs: 4.3 ft2 (0.4 m2)

• Low-floor bus wheel well: 10.0 ft2 (0.95 m2) each

3. Calculate the standing passenger area. Subtract the area calculated in step 2 from the gross interior floor area calculated in step 1 (TCQSM, 3-44).

At LOS “A” load levels, passengers are able to spread out and can use empty seats to store parcels and bags rather than carry them on their laps. At LOS “B,” some passengers will have to sit next to others, but others will not. All passengers can still sit at LOS “C,” although the choice of seats will be limited. Some passengers will be required to stand at LOS “D” load levels, while at LOS “E,” a transit vehicle will be as full as passengers will normally tolerate. LOS “F” represents crush loading levels (TCQSM, 3-45).

This calculation provides the load factor. The load factor gives the agency an idea of how crowded a vehicle would be based on passengers seated/standing and available vehicle space. Crush loads are the maximum feasible passenger capacity of a vehicle (that is, the capacity at which one more passenger cannot enter without causing serious discomfort to others. Note that the crush load specification for some rail transit vehicles does not relate to an achievable passenger loading level but is an artificial figure representing the additional weight for which the car structure is designed or which the propulsion and braking system will meet minimum performance criteria), but are generally not considered to be safe for the passenger and therefore not desirable (TCQSM, 8-8).

Person Capacity Factors

(TCQSM, 4-17)

Person capacity is defined as the maximum number of people that can be carried in one direction over the section of a route, in a given period of time, typically 1 hour, under specified operating conditions, without reasonable delay, hazard or restriction, and with reasonable certainty (TCQSM, 5-5).

This definition is less absolute than theoretical line capacity [number of vehicles per direction, per hour, per direction times the maximum design load of each vehicle (TCQSM, 8-8)], as it depends on the number of vehicles, the length/crush-load capacity of the vehicles, passenger loading standards, and variations in passenger demand between vehicles and between individual cars (TCQSM, 5-5).

Loading diversity is provides an important distinction between a line’s theoretical capacity and a more realistic person capacity that can actually be achieved on a sustained basis. The theoretical capacity assumes that all the offered capacity can be used by passengers. In practice (reality), this only occurs when a constant queue of passengers exists to fill all available seats and standing room. In reality, transit passengers do not generally arrive at an even rate over the course of an hour, and generally do not distribute themselves evenly among the vehicle or vehicle consists. Accounting for loading diversity allows one to determine the number of people that can be accommodated during an hour without pass-ups occurring (pass-ups being the bus passing a waiting passenger due to the load of the vehicle reaching maximum passenger capacity) (TCQSM, 5-5).

When I speak of diversity I’m not talking about the demographic make-up of the vehicle, rather the spread of persons within/among the vehicle.. (i.e. where are people standing when they board and distribute themselves among a vehicle?)

Therefore, constraints must be considered: available passenger space; loading diversity within a car; the loading diversity among the cars; the unevenness of passenger demand over the peak hour (measured by Peak Hour Factor) (TCQSM, 5-5).


Loading Diversity

How passenger demand is distributed spatially along a route and how it is distributed over time during the analysis period affect the number of boarding passengers that can be carried. The spatial aspect of passenger demand, in particular, is why person capacity must be stated for a maximum load section and not for a route or street as a whole (TCQSM, 4-16).

Over the course of an hour, passenger demand will fluctuate. The peak hour factor, reflects passenger demand volumes over (typically) a 15-minute period during a peak hour. A bus system should be designed to provide sufficient capacity to accommodate this peak passenger demand. However, since this peak demand is not sustained over the entire hour and since not every bus will experience the same peak loadings, the achievable person capacity during the hour will be less than that calculated using peak-within-the-peak demand volumes (TCQSM, 4-17).

(TCQSM, 4-5).

The average passenger trip length affects how many passengers may board a bus as it travels its route. If trip lengths tend to be long (passengers board near the start of the route and alight near the end of the route), buses on that route will not board as many passengers as a route where passengers board and alight at many locations. However, the total number of passengers on board buses on each route at their respective maximum load points may be quite similar.

The distribution of boarding passengers among bus stops affects the dwell time at each stop. If passenger boardings are concentrated at one stop, the facility’s bus capacity will be lower, since that stop’s dwell time will control the bus capacity (and, in turn, the person capacity) of the entire facility. Both the potential bus capacity and person capacity at the maximum load point are greater when passenger boarding volumes are evenly distributed among stops (TCQSM, 4-17).

Operator Policy

Two factors directly under the control of a transit agency are the maximum schedule passenger load allowed on buses (set by a combination of agency policy and agency vehicle purchasing decisions) and the service frequency. Maximum schedule load is synonymous with “capacity,” assuming a reasonable number of standees. It represents the upper limit for scheduling purposes. Maximum schedule loads are typically 125 to 150% of a bus’s seating capacity, for example 54 to 64 passengers on a typical 40-foot (12-meter) bus.

Crush loads, typically loads above 150% of a bus’s seating capacity, subject standees and other passengers to unreasonable discomfort. Such loads are unacceptable to passengers. Crush loads prevent circulation of passengers at intermediate stops and so induce delay and reduce vehicle capacity. Although crush loading represents the theoretically offered capacity, it cannot be sustained on every bus for any given period, and it exceeds the maximum utilized capacity. Therefore, crush loads should not be used for transit capacity calculations. Note, however, that when maximum schedule loads are used, some buses will experience crush loading, due to the peaking characteristics of passenger demand (TCQSM, 4-17).

An agency whose policy requires all passengers to be seated will have a lower potential person capacity for a given number of buses than an agency whose policy allows some standees or an agency that purchases longer buses. The bus frequency determines how many passengers can actually be carried, even though a bus stop or facility may be physically capable of serving more buses than are actually scheduled.

This last point is important when reporting person capacity: is the capacity being referred to the maximum number of people that can be carried under the current schedule, or the maximum number of people that could be carried if all of the buses a facility could accommodate were scheduled? This equation illustrates the differences in calculating the two and is applicable to either bus routes or facilities.

When different sizes of buses are scheduled to use a facility, a weighted average maximum schedule load per bus should be developed, based on the number of buses of each type and the loading applied to each bus type. Typical bus vehicle types, dimensions, and passenger capacities:


Low-floor buses typically provide five or six fewer seats than a manufacturer’s equivalent 35 to 40 foot (10.7-12.2 meter) high-floor bus, due to the space taken up by the wheel wells that is not used for seating. Low-floor articulated buses have been introduced by some transit agencies (TCQSM, 4-18).

Constraints on staff and equipment resources must also be considered. Line capacity considers how many vehicles could be operated, assuming no constraints on the supply of cars, nor any constraints on the number of operators available to drive those vehicles. Knowing, and designing for, the ultimate person capacity of a line is often important in long-term planning. However, it may just be as important to know in the short term how many vehicles can be operated and the person capacity of those vehicles, given existing resources (TCQSM, 5-5).

Why is this or should this be interesting to you? Well, it’s probably not – that is, unless you’re a transit geek (like me). But what should be interesting is that ‘yes, there are actually scientific, measurable calculations that go into planning and determining what is acceptable level of space on a transit vehicle. However, just like anything else that can be quantitatively measured, the opinions and perceptions of the transit user are just as important as actual quantified passenger data collected via automated passenger counter data, load data, ride checks, etc or estimated using these models (please note that there are many more complex models for estimating or calculating vehicle capacity and passenger area).

So, do transit planners even realize that I’m standing with my nose in someone’s armpit? Yes, we do. Do we attempt to mitigate this situation to the extent possible (based on customer perceptions, actual data, funding availability and cost effectiveness?) Of course!

If I am standing with my nose in someone’s armpit on a daily basis, should I blame my fellow riders for accepting this level of service? Not necessarily. Don’t forget that financial/budget availability for service delivery, as well as cost/cost-effectiveness; both of which are huge factors to determining a planner’s ability to deliver service.

Furthermore, based on available funding and operator policies, ranges can vary from agency-to-agency and from city-to-city. The TCQSM, ranges are not intended to set national standards. Decisions of this nature are left to the judgment of local agencies, based on community and agency/operator goals and objectives, development and demographic patterns, and available agency resources.

So, are transit riders in larger cities/systems simply more accepting of reduced personal space because their values are different? Perhaps. Does the acceptable range for passenger area generally follow Maslow’s hierarchy of needs?  Have they just reached a point where they are willing to accept a lower level of service and personal space as long as their basic transportation need is being met?

What do you think?


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