In
public transportation
Public transport (also known as public transportation, public transit, mass transit, or simply transit) is a system of transport for passengers by group travel systems available for use by the general public unlike private transport, typical ...
, schedule adherence or on-time performance refers to the level of success of the service (such as a
bus
A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for cha ...
or
train
In rail transport, a train (from Old French , from Latin , "to pull, to draw") is a series of connected vehicles that run along a railway track and Passenger train, transport people or Rail freight transport, freight. Trains are typically pul ...
) remaining on the published schedule. On time performance, sometimes referred to as on time running, is normally expressed as a percentage, with a higher percentage meaning more vehicles are on time. The level of on time performance for many transport systems is a very important measure of the effectiveness of the system.
Background
On time performance is a measure of the ability of transport services to be on time. Almost all transportation systems have
timetables
A schedule or a timetable, as a basic time-management tool, consists of a list of times at which possible tasks, events, or actions are intended to take place, or of a sequence of events in the chronological order in which such things are ...
, which describe when vehicles are to arrive at scheduled stops. Transport services have a higher utility where services run on time, as anyone planning on making use of the service can align their activities with that of the transport system. On time performance is particularly important where services are infrequent, and people need to plan to meet services.
The ability of different
transport modes to meet on time performance statistics depends on the degree to which they are affected by external factors. For example, rail services often operate on a separated
right of way
Right of way is the legal right, established by grant from a landowner or long usage (i.e. by prescription), to pass along a specific route through property belonging to another.
A similar ''right of access'' also exists on land held by a gov ...
, and so are not affected by road congestion. Buses, unless they are separated from road traffic, will be heavily affected by
congestion.
To calculate the percentage of vehicles on time, comparison is needed with the timetable. A comparison is often completed for arrival time rather than departure time, but both are common. Departure times are normally more on-time than arrival times, as incidents and breakdowns occur that reduce the on time performance. When the comparison is made between the timetable, and the actual arrival or departure time, a rule is applied to determine how much of a deviation is permitted. For example, if a bus is 4 minutes 20 seconds late, a rules may be applied that a bus is only late when later than 5 minutes, so this service would be counted as on time. The choice of threshold for lateness is an important one, with a low threshold resulting in a lower on time performance statistic. A high threshold will result in more services on time, but may result in the managing corporation or government body being accused on not reporting correctly.
Passengers can be updated on the movement of transport vehicles with
passenger information systems
A passenger information system, or passenger information display system, is an automated system for supplying users of public transport with information about the nature and the state of a public transport service through visual, voice or other m ...
. These systems display the arrival time of vehicles to stops, stations or airports, and typical information displayed is the time in minutes to the next scheduled arrival. Some of these systems have been extended to include apps to show the movement of trains/buses/planes/ferries. Where services are delayed, more information can be provided, such as alternative transport options, or estimated time till services resume.
A small number of transport systems operate on the principle of go-when-full. This type of transport system will not have any meaningful measure of on time performance.
Airlines
Airlines are closely monitored on their on time performance. Numerous websites exist for reporting on punctuality for airlines, often operated by government departments.
Iraqi Airways, an airline, uses a rule that aircraft that depart within 15 minutes of scheduled departure are on time. The 15 minutes rules for on time performance is commonly applied throughout the airline industry. Airlines typically perform well when their on time performance reaches 90%.
OAGan
Ciriumregularly publish airline on time performance rankings and data.
On time performance for aircraft is simple to calculate as aircraft depart and arrive at
airport
An airport is an aerodrome with extended facilities, mostly for commercial air transport. Airports usually consists of a landing area, which comprises an aerially accessible open space including at least one operationally active surface ...
s, and these are clear points to complete the on time performance calculation. Things are substantially less clear for bus services, where an on time performance can be calculated for each and every stop. One method is to calculate on time performance for only the start and end of the bus route, which can produce meaningful statistics. One problem with this method is where very large stops or interchanges are not at the start and end of the bus journey, but in the middle, and the start and end of the route are bus depots or other small stops for which on time performance statistics are not as important. In this situation on time performance may be calculated at the major interchange, rather than the start and end.
Buses
On bus services an on time performance can be calculated for each and every stop. One method is to calculate on time performance for only the start and end of the bus route, which can produce meaningful statistics. One problem with this method is where very large stops or interchanges are not at the start and end of the bus journey, but in the middle, and the start and end of the route are bus depots or other small stops for which on time performance statistics are not as important. In this situation on time performance may be calculated at the major interchange, rather than the start and end.
Bus routes are frequently late, given buses mix with road traffic.
Bus rapid transit
Bus rapid transit (BRT), also called a busway or transitway, is a bus-based public transport system designed to have much more capacity, reliability and other quality features than a conventional bus system. Typically, a BRT system includes ...
is bus based mass transit system, where road infrastructure has been specifically constructed to allow better on time performance, and more frequent and high speed services. This type of bus system is far less exposed to problem of low on time performance statistics than regular bus services. Trying to get to the school on time can be a big hassel for drivers. This results in 76 percent of schools in Ontario and Quebec to have late departures by chance not choice.
Light rail
Light rail, whilst being a rail system, can be exposed to problems with poor on time performance. This is especially the case where rail service operate in the middle of congested roads, and where a light rail system has a separate right of way the on time performance will be better.
Transport hubs
Users of transport systems often use several transport modes to complete a journey. They will change transport modes at a
transport hub
A transport hub is a place where passengers and cargo are exchanged between vehicles and/or between transport modes. Public transport hubs include railway stations, rapid transit stations, bus stops, tram stops, airports and ferry slips. F ...
, and all transport modes have some kind of transport hub.
On time performance is important to interchanges. Where on time performance is poor, passengers or goods may miss a connection, and so be forced to wait. In some cases the transit time allowed from one transport mode to another may be very small, and so any lateness can result in services being missed. Where services are infrequent, such as a long distance train trip, or a flight, then the consequences of late services can be high. Transport systems that exist to deliver passengers and services to interchanges should be particularly concerned with achieving a good on time performance.
Measurement
Typically on time performance is measured by comparing each service with its schedule. A threshold is chosen for how late a service can be before it is determined to be late.
The scale of delays are often calculated in delay minutes. A delay minute is the number of minutes a service is delayed multiplied by the number of passengers on board the transport vehicle.
Network Rail
Network Rail Limited is the owner (via its subsidiary Network Rail Infrastructure Limited, which was known as Railtrack plc before 2002) and infrastructure manager of most of the railway network in Great Britain. Network Rail is an "arm's leng ...
, a large rail infrastructure provider in the UK, uses passenger delay minutes as a mechanism to reward and punish for services being on time and late respectively. Using delay minutes as a measure allows for comparisons between heavily loaded large transport vehicles, and much smaller or lightly loaded vehicles. The economic cost of a large transport vehicle being delayed is much greater than a service that is almost empty.
Factors
There are many factors that can affect on-time performance. Depending on the situation, the service may face regular delays or a service that usually performs on time may be occasionally behind schedule. Some of these factors include:
*
Traffic congestion
Traffic congestion is a condition in transport that is characterized by slower speeds, longer trip times, and increased vehicular queueing. Traffic congestion on urban road networks has increased substantially since the 1950s. When traffic de ...
:
**Bus transport: The volume of automobile traffic on the bus's route can affect the bus's ability to keep on the schedule. While a route that is free of obstruction can remain on schedule or even move ahead of schedule,
heavy traffic
''Heavy Traffic'' is a 1973 American live-action/animated drama film written and directed by Ralph Bakshi. The film, which begins, ends, and occasionally combines with live-action, explores the often surreal fantasies of a young New York City ...
can slow down the bus behind its schedule. This can be due to regular conditions at the time of day, or an occasional or one-time event, such as a
sports game
A sports video game is a video game that simulates the practice of sports. Most sports have been recreated with a game, including team sports, track and field, extreme sports, and combat sports. Some games emphasize actually playing the sport (s ...
or
festival
A festival is an event ordinarily celebrated by a community and centering on some characteristic aspect or aspects of that community and its religion or cultures. It is often marked as a local or national holiday, mela, or eid. A festival c ...
that draws a large crowd.
**Rail transport: The volume of traffic on the route can cause even more delays for rail vehicles, because of tight scheduling at
sidings and other meet points. On passenger railroads, freight traffic is especially problematic because of the length and slow acceleration of the
freight train
Rail freight transport is the use of railroads and trains to transport cargo as opposed to human passengers.
A freight train, cargo train, or goods train is a group of freight cars (US) or goods wagons (International Union of Railways) haul ...
s.
**Ferries are often affected by congestion at quays and piers. One report reported a third of all delays are caused by congestion.
*
Accident
An accident is an unintended, normally unwanted event that was not directly caused by humans. The term ''accident'' implies that nobody should be blamed, but the event may have been caused by unrecognized or unaddressed risks. Most researcher ...
: A collision that obstructs traffic flow can also tie up vehicles on the route until the accident is cleared and therefore cause them to be behind schedule.
*
Breakdown
Breakdown may refer to:
Breaking down
*Breakdown (vehicle), failure of a motor vehicle in such a way that it cannot be operated
*Chemical decomposition, also called chemical breakdown, the breakdown of a substance into simpler components
*Decompo ...
: A disabled bus or train, besides being unable to complete its own route, may slow down others that follow on the schedule. As riders scramble to board a subsequent bus or train on the schedule, the higher ridership levels on that run may slow it down. Additionally, on a rail line, a disabled train may block other trains from passing, or may require track-sharing with opposing trains, thereby slowing service in both directions.
*
Detour
__NOTOC__
A detour or (British English: diversion) is a (normally temporary) route taking traffic around an area of prohibited or reduced access, such as a construction site. Standard operating procedure for many roads departments is to route an ...
: A road closure that forces the bus to temporarily deviate from its regular route may cause it take more time than planned to reach its destination.
*
Passenger load: When a special event takes place, the service may experience higher ridership levels than usual, leading to more time the bus or train may have to spend allowing passengers to board and depart.
*
Unrealistic scheduling: Many public transportation agencies are tax-subsidized, and therefore are often cash-strapped while attempting to maximize service provided to customers. In such cases, schedules that are written do not provide enough time for operators to travel along the route in the time allotted, and
layover
250px, Layover for buses at LACMTA's Warner Center Transit Hub, Los Angeles ">Los_Angeles.html" ;"title="Warner Center Transit Hub, Los Angeles">Warner Center Transit Hub, Los Angeles
In scheduled transportation, a layover (also waypoint, way ...
s are too short to allow enough recovery time, thereby seriously delaying the service on a regular basis.
*
Weather
Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmosphere, the ...
: Inclement weather may cause a bus that usually remains on schedule to be behind as a result of precautions that must be taken by the vehicle's operator and other vehicles on the road. Trains might have to operate slower as a result of
slippery rail
Slippery rail, or low railhead adhesion, is a condition of railways (railroads) where contamination of the railhead reduces the traction between the wheel and the rail. This can lead to wheelslip when the train is taking power, and wheelslide ...
during the autumn season, and high wind can affect
signal systems.
*Crewing issues. Crew may be late to work, or be at the wrong place at the wrong time. Alternatively, they may make mistakes that delay services.
Effects of poor on-time performance
The effect of delays to a transport system are normally calculated as costs in dollars, either to the passengers, or to the transport provider. The transport provider will incur costs of the additional use of the vehicle, crew costs, and fuel. In many cases the cost is calculated as a dollar value per minute. The total cost of delays for an entire transport system for one year can be very large.
In many publications the effect of poor on time performance is equated to lost money. As passengers are delayed, this delay is equated to dollars, and this is the amount that is lost. Calculations are performed for the total amount "lost" per year for different countries, for example, for the US it was estimated that the cost to the country was $32.9 billion in 2007. The total amount of cost per country per year can be very large.
An economic cost is calculated through the following formula:
The delay cost per minute is calculated as the addition of direct costs to a service provider, and the economic cost to passengers through lost time. This is:
The economic cost per minute for passengers is often expressed as a percentage of the average in the area. For different transport modes the cost per minute may be different, as those using buses may have a lower income than those using trains.
Buses when late may experience a problem known as
bus bunching
In public transport, bus bunching, clumping, convoying, piggybacking or platooning is a phenomenon whereby two or more transit vehicles (such as buses or trains) that were scheduled at regular intervals along a common route instead bunch togethe ...
. On some bus lines with a more frequent service, if one bus falls behind schedule passenger numbers waiting at bus stops may grow, required a longer
layover
250px, Layover for buses at LACMTA's Warner Center Transit Hub, Los Angeles ">Los_Angeles.html" ;"title="Warner Center Transit Hub, Los Angeles">Warner Center Transit Hub, Los Angeles
In scheduled transportation, a layover (also waypoint, way ...
time. One or more subsequent buses on the published schedule may pass these already cleared stops and have a nearly empty run, and may actually jump ahead of their scheduled time to the point that two or more buses are within close sight of one another. In some cases, one bus is able to pass another. This phenomenon is sometimes known as ''clumping'' or ''bunching''. When this occurs, the even spacing of buses on the schedule may be severely disrupted, leading to extremely long waits for those attempting to catch a bus, and multiple buses arriving at once. Bus bunching serves to reduce the effectiveness of buses as a transport mode.
Improving schedule adherence
Transit agencies often take the following measures in attempts to improve schedule adherence on their routes:
*Providing better information to drivers on their schedule and on time performance. Bus and rail drivers may not know if they are on time as this information is not commonly provided. A driver advisory system (DAS) can provide better information, and can inform drivers of their correct departure and arrival time.
*Adding additional
route capacity
Route capacity is the maximum number of vehicles, people, or amount of freight than can travel a given route in a given amount of time, usually an hour. It may be limited by the worst bottleneck (engineering), bottleneck in the system, such as a ...
, so the effect of bottlenecks is reduced. Capacity constraints are common in many transport systems, and adding capacity is normally an effective way to reduce delays.
*Modify schedules by adding running time, known as
schedule padding
Schedule padding—sometimes called simply padding, or recovery time—is some amount of 'additional' time added to part or all of a schedule, in excess of the expected duration, that allows it to be resilient to anticipated delays and increase th ...
. This is the most common solution, but agencies often add running time by cutting layover time, which adversely affects the ability to recover from unplanned incidents. If layover time is to remain the same, it may require an increased expenditure in the system's budget or a slight reduction in the number of trips.
*Increasing the number of reserve vehicles. All transport vehicles can experience engineering failures, which cause them to be unavailable for service. Increasing the number of reserve vehicles increases costs, but allows vehicles to be replaced when needed. For this strategy to work vehicles need to be placed at strategic locations.
*Modifying routes to a route where buses can be less obstructed, when this does not interfere with the ability of riders to reach their buses.
*Building bus and rail lines which are
grade separated
In civil engineering (more specifically highway engineering), grade separation is a method of aligning a junction of two or more surface transport axes at different heights (grades) so that they will not disrupt the traffic flow on other tra ...
from road traffic.
*For airlines, delays are often caused by ground processing at airports, so improving the airport plane and passenger handling can have a big effect of on time performance.
*Splitting a long route into two or more shorter ones, as shorter routes are more likely to remain on schedule. Shorter routes generally are exposed to fewer problems.
*Some cities have introduced
bus rapid transit
Bus rapid transit (BRT), also called a busway or transitway, is a bus-based public transport system designed to have much more capacity, reliability and other quality features than a conventional bus system. Typically, a BRT system includes ...
services or limited stop lines on long, overcrowded routes. This involves the use of part of the route's budget to operate another line on the same route that stops only at key points. While the overall frequency of the original route is reduced, riders traveling over a longer distance have the option of obtaining a quicker trip on the limited-stop line.
*Some agencies and transport companies have installed
GPS
The Global Positioning System (GPS), originally Navstar GPS, is a Radionavigation-satellite service, satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of t ...
devices on their buses and trains to monitor the locations of the vehicles. By linking this real-time information with stop locations and predicted travel-times, the estimated time of arrival of the next service is then displayed at some stops.
*Customer interfaces: Some agencies and companies have made the GPS tracking data described above available to public transport users online, by a
toll free number
A toll-free telephone number or freephone number is a telephone number that is billed for all arriving calls. For the calling party, a call to a toll-free number from a landline is free of charge. A toll-free number is identified by a dialing prefi ...
, or through the
mobile web
The mobile web refers to mobile browser-based World Wide Web services accessed from handheld mobile devices, such as smartphones or feature phones, through a mobile or other wireless network.
History and development
Traditionally, the World ...
.
Real-world examples
The following chart shows some examples of real-world on-time performance. The figures are always (unless stated otherwise) per vehicle, not per customer.
See also
*
Flight cancellation and delay
A flight delay is when an airline flight takes off and/or lands later than its scheduled time. The United States Federal Aviation Administration (FAA) considers a flight to be delayed when it is 15 minutes later than its scheduled time. A cancella ...
References
* The compilation of statistics for on time performance is possible only for transport providers that publish these statistics. Where the performance is poor, they tend to be reluctant to publish anything. For example, Amtrak was having legal issues in 2013 with track access, and so on time performance dropped. It was very difficult to find any recent figures on the performance for Amtrak.
External links
"Australian Government Monthly On Time Performance Reports"ASCE Research Library AATT 2006 Applications of Advanced Technology in Transportation 9th International Conference Kelvin C. P. Wang, Brian L. Smith, Donald R. Uzarski, S. C. Wong - Editors, August 13–16, 2006, Chicago, Illinois, USA*
ttp://www.tc.gc.ca/programs/Environment/utsp/casestudypublictransit.htm Case Study Public Transit - Service and Operationsbr>
MTR Corporation of Hong Kong Website, report on On-Time PerformanceAmtrak Corporate Website, reporting on on-time performance
{{buses
Public transport
Transport reliability
Transportation planning
Scheduling (transportation)