Investigation of Reliability: London Underground Jubilee Line

Sponsor: CPC Project Services iqp (2)
Sponsor Liaison: Malcolm Dobell
Student Team: Jack Agolli
Marianna Bailey
Berwin Jayapurna
Yiannis Kaparos

Metro systems are often faced with reliability issues; specifically pertaining to safety, accessibility, train punctuality, and stopping accuracy. The project goal was to assess the reliability of the London Underground’s Jubilee Line and the systems implemented during the Jubilee Line extension. The team achieved this by interviewing train drivers and Transport for London employees, surveying passengers, validating the stopping accuracy of the trains, measuring dwell times, observing accessibility and passenger behavior on platforms with Platform Edge Doors, and overall train performance patterns.



Investigation into Reliability of the Jubilee Line

CPC Final Presentation

Executive Summary

Public transportation is one of the key pillars of any modern metropolis. With growing populations in cities, public transportation inevitably faces challenges. In order to continue being a valuable service, these systems need to be reliable, accessible, and safe for passengers. A proven solution to all of these challenges, applicable around the world, is modernization of public transportations systems (UITP, 2016). Rail transportation is a major part of public transportation networks and is one of the best alternatives to driving, due to its improved speed and convenience (Eagling & Ryley, 2015). An ideal rail system in a major global city would be equipped with the latest technologies and would operate at peak efficiency by every possible measure. In reality, most systems cannot afford the initial costs necessary to modernize and are plagued with a wide variety of problems. London Underground (LU) for instance, the underground rail transportation system in London, faces serious problems across its lines due to the combination of excessive demand and a relatively outdated system (Morley, 2017).



In accordance to the Disability Discrimination Act of 1995, London Underground is committed to creating a seamless journey for anyone who may need special assistance, including riders who are elderly, pregnant, those who have mobility, hearing, or vision impairments. In the United Kingdom alone, there are 10 million people living with a disability, making up 20% of the population (Customer Standards & Experience Manager, 2008). As of April 2017, however, only 71 of the 270 stations on the Underground provide any form of step-free access for mobility impaired users. This means that only about a quarter of the network can be used by everyone, including those with disabilities. In December of 2016, Mayor Sadiq Khan promised to spend £200 million on making at least 30 more stations step-free, but this is a long and complicated process (Pring, 2016).

Safety is another important aspect that London Underground is committed to improving. The Platform Train Interface (PTI), or the gap between the train and the platform, poses the greatest safety threat for passengers. The PTI accounts for 21% of safety risks and 48% of fatality risks (RSSB, 2015). Moreover, overcrowding on the platform and inattentive riders getting too close to the train can lead to accidents. To ensure the passengers travel safely, London Underground has numerous regulations and strategies. The PTI is monitored by the train driver and control center through CCTV and customer behavior is influenced by the “mind the gap” and other announcements, signs, and yellow lines. There is also additional station staff present at the platforms during peak hours to direct passengers, provide organization, and prevent any potential track intrusions (Customer Standards & Experience Manager, 2014).

One of the most recently constructed lines is the Jubilee Line. In 1932, the first part of what is now the Jubilee Line was built to connect Baker Street and the Stanmore branch as a part of the Bakerloo Line. Since then, the line has been extended in two phases. In 1979, the branch was extended to connect with Charing Cross tube station in central London, and the section from Stanmore to Charing Cross became the Jubilee Line, separate from the Bakerloo Line. In 1999, the Jubilee Line Extension (JLE) connected the line to Stratford Station in east London (London Underground: Jubilee Line, 2017). The JLE involved building 11 new stations, 8 of which have Platform Edge Doors (PEDs), as shown in Figure 1, a unique feature in the London Underground. In mid-2000s, a new signaling and train control system, called Transmission Based Train Control (TBTC) was introduced in the Jubilee Line. Today, Jubilee Line accommodates 213 million passengers per year throughout its 27 stations (Jubilee Line, 2017).

platform edge doors

Figure 1. Picture of Platform Edge Doors (PEDs) in North Greenwich Station


Project Goal & Objectives

The project goal was to investigate the reliability of the modern train technologies implemented during the Jubilee Line Extension. We completed this in collaboration with CPC Project Services, a private consultancy firm that is working with Transport for London (TfL). For this project, we defined reliability as the benefits and limitations of the modern technologies, their effect on dwell time and safety, and their accessibility for all train riders. We evaluated this by surveying passengers about the modern technologies, interviewing drivers, duty reliability managers (DRMs) and senior Transport for London (TfL) staff, observing accessibility, behavior of passengers around the PTI, station signage, and overall train performance patterns, and measuring the stopping accuracy and dwell times on the Jubilee Line stations.

Our definition of reliability can be broken down into four objectives from both human and technical perspectives:

  1. Investigation of the safety measures on Jubilee line, including how passengers behave at stations with and without PEDs and the precautions taken at each platform.
  2. Evaluation of the accessibility of the trains and stations for all passengers, and how the PEDs affect accessibility.
  3. Assessment of how modern technologies, specifically Automatic Train Operation (ATO) and PEDs, affect the punctuality of the Jubilee line trains, particularly in relation to changes in the dwell time.
  4. Validation of the TBTC system that currently measures the stopping accuracy of trains on stations that are PED equipped.


Once the objectives were fulfilled, we formed recommendations on how to improve the reliability of the line.



To analyze the social implications of improving the reliability of the Jubilee Line, we collected a wide array of data, ranging from passenger surveys and employee and driver interviews, to station observations and stopping accuracy measurements. In order to gather information about riders’ opinions on the reliability and accessibility of trains in the Jubilee Line, we conducted an in-person and online version of a survey. We collected 104 survey responses from a diverse group of riders, with 35% of riders being between ages 18 and 24, 37% between the ages of 25 and 39, and 26% between the ages of 40 and 65, the majority of whom had ridden the Jubilee Line before. To gain a better understanding of the London Underground system from the employee’s point of view, we performed interviews with train drivers, Duty Reliability Managers (DRMs), and senior Jubilee Line staff. Since the PTI is the greatest threat for passengers, we also performed observations of the PTI on various Jubilee Line stations. Finally, we completed manual stopping accuracy and dwell time measurements in order to validate the measurements made by the TBTC system. Stopping accuracy is one of the most significant measurements of an Automatic Train Operation (ATO) system’s efficiency (Ma & Zeng, 2014, p. 1237). By determining if a train is stopping accurately and whether the measurement system is accurate, a wide range of systematic problems can be revealed.


Findings & Discussion

Regarding safety, we found that the PEDs improve the safety of the passengers as they act as a barrier to prevent intentional or unintentional falling to the track. Of the 104 passenger survey responses, 74% of passengers felt safer at platforms equipped with PEDs. In addition, only 15% ever had a bad experience with PEDs. In terms of drivers, the unanimous consensus was that all six felt safer and more relaxed driving trains on the Jubilee Line, especially at stations equipped with PEDs. PEDs improve safety as they prevent people from intentionally or unintentionally falling into the track. This means that the train operation is not interrupted by track intrusion, and the number of accidents will significantly decrease. All riders feel safer to stand closer to the PTI when waiting for the train to approach, as there is a barrier separating them from the track. This makes the drivers feel more relaxed when driving the train. PEDs provide positive collateral effects such as providing psychological benefits of reducing staff and riders’ trauma from witnessing accidents. The cost to society of a single incident of a person jumping into the track is estimated to be over one million pounds. With around 250 suicide cases in main railways per year, the costs associated with suicide become very significant (Dobell, Personal Communication, March 27, 2017). PEDs also make stations look more modern and new, and we suspected that this was one of the reasons why the Jubilee Line is the most popular among our survey responses. On the other hand, PEDs have various drawbacks, namely the costs of implementation and maintenance. The current system that controls PEDs is independent of Transmission Based Train Control (TBTC), hence issues arise as a result of the two systems not working in conjunction. It is therefore important to reconsider other factors that may contribute to improving safety. The first one is consumer behavior. According to the SCM and GM of Jubilee Line, consumer behavior is very unpredictable and difficult to control. O’Hare mentioned that TfL has conducted different studies to understand consumer interaction with instructions, signs, announcements, etc. They found that even the smallest detail, such as size of the platform, can change the way people behave. They also noticed that human behavior may be altered in one particular station where relevant signs are in place, but once they move on to a different station, they switch back to their old habits. These findings show that passengers are very unpredictable and thus improving safety is much more complicated than modernizing a system.

Our accessibility evaluation showed that the Jubilee Line is more accessible to all riders compared to other lines in the Underground, due to the physical systems and organizational policies that are in place. The new Jubilee Line stations are all equipped with lifts, escalators, level boarding areas, and signs denoting which cars are level at certain older stations, like Green Park, to allow for easy alighting. This is a result of the relatively new legislation that established regulations to ensure that public transportation is accessible to everyone that wishes to use it. Unfortunately, the previously mentioned features are not implemented at all stations. According to our conversations with senior Jubilee Line staff and the project sponsor, all of the newly built Underground stations will be built to allow for step-free access. The most significant limiting factor in upgrading older stations is the lack of funds. In an ideal word, London Underground would have enough money to install lifts, ramps, and level access at all stations. Moreover, there are significant technical difficulties in upgrading older stations by installing accessibility features. Many of the old stations do not have room to easily install lifts to allow step free access from the street to the platform. As a result, small fixes will have to be implemented to accommodate anyone who needs assistance getting to the platform.

The team’s data analysis showed that many factors affect train punctuality. Both of the senior Jubilee Line employees the team interviewed said that passenger behavior is the most significant factor of delays. Therefore, before any further technological improvements are made, TfL needs to reach out to the customers. Both interviews said that the reason behind this behavior is that passengers are not aware of the system around them and the effect their actions can have on it. Inattentive and careless behavior causes delays on the line when passenger try to rush onto the trains at the last moment and end up running into the doors, drop items down on the track, and miss major announcements. Survey responses support the presence of such behaviors. The interviews also discussed the major impact of a single, small delay on the line. The Jubilee Line General Manager emphasized that if there is a delay in the morning peak, it will ruin the time table for the remainder of the day. Our dwell time analysis showed that the PEDs add very small amounts of time in the total dwell time. The increase in the average dwell time was small enough that the total effect in delays is negligible, even over a full day of operation. Moreover, the stations with PEDs showed more consistency regarding the dwell time. This is very important because the consistency allows for better scheduling, since the dwell times are more predictable.

The team’s stopping accuracy data analysis revealed the following important results. First, we compared the stopping accuracy data obtained from the Vehicle Control Centre (VCC) to the manual measurements we performed. We found the VCC to be measuring the stopping accuracy correctly more than 96% of the time at PED stations, in that it matched the measurements of the manual measurement system. This means that the currently installed system is sufficient for measuring the stopping accuracy, although an automated version of the manual measurement system could be developed. Second, the VCC data for all the trains on the Jubilee Line for March 1st to 26th showed that the trains are consistently stopping accurately. Driver interviews also supported this finding as all of them said that in their experience, the trains have never stopped outside the tolerance. Third, the measurements done by the VOBC, at a 5cm resolution, did not match our manual measurements for the majority of cases. It should be noted that the VOBC data analysis was done with very few data points, so a definite conclusion cannot be made at this stage.

The stopping accuracy measurement results affect everyone involved in the Jubilee Line: passengers, train operators, platform and station staff, as well as senior management staff. On the passenger level, it means that it is extremely rare that a passenger will be obstructed while boarding or alighting the trains (at stations with PEDs). This means that more passengers will be able to get in and out of the trains and get to their destination without any disturbances. Moreover, the reliability of the stopping location of the trains at stations both with and without PEDs allows for the passengers on the platform to queue in an orderly fashion around the locations where the train doors will be, resulting in much more efficient alighting-boarding process; as a result, the passenger-carrying capacity of the line can be maximized, and delays will be positively impacted as well. From the perspective of the train drivers, very accurate, consistent stopping allows them to operate the train doors quickly, keeping the dwell times to a minimum. For the platform staff, accurate stopping is welcome because the reduced customer disturbances mean that the staff members will not have to intervene with passenger behavior as often. Finally, accurate stopping is important for senior staff of the line because it means that the investments in the modernization of the Underground have positive effects on the daily operation, and should therefore continue.



We investigated similar railway systems around the world, including the most advanced and newest ones, and previous research, and came up with original ideas to improve reliability on the line. We examined the Paris Metro because of its similarity as an older system in a large global city, whereas Copenhagen Metro and Singapore Mass Transit were looked at because of their recently built, modern systems. The following recommendations were proposed:

  1. Triple poles (Figure 2, Top Left) in the center of train cars to allow passengers to more safely and easily stand near the center of the car, to address safety and punctuality. The team’s in-train observations showed it is often difficult for many passengers to stand near the center and grip the single pole during peak times.
  2. Platform markings on non-PED stations (Figure 2, Top Right), to address safety, punctuality, and stopping accuracy. These markings would provide passengers with an idea of where the train doors are going to open, allowing passenger to wait and queue in the right area, which will work since our verification showed that the trains are in fact stopping accurately with the TBTC system. The markings will also encourage passengers on the platform to stand on the side of the door opening area, to avoid obstructing passengers exiting the train, a problem the team noticed daily.
  3. Metal railings (Figure 2, Bottom Left) to improve safety as a less costly barrier for the PTI than PEDs and to address stopping accuracy and punctuality. Retrofitting PEDs can be very costly, and even impossible in some stations due to their mechanical and electrical complexity. Metal railings serve a similar purpose to PEDs, in that they prevent passengers from falling onto the track and can also be used to direct passenger flow. These metal railings would be placed along the platforms in the areas between the train doors.
  4. Connected cars (Figure 2, Bottom Right), like the ones that are already implemented in the Metropolitan, Circle, District, and Hammersmith & City lines, which would allow better distribution of passengers along train cars, thus addressing accessibility and punctuality. Connected cars also allow passengers to move along the whole train, especially those with wheelchairs, strollers, or luggage.
  5. Mechanical gap fillers to bridge the gap at the PTI on platforms where it is large. These mechanical gap fillers are extended from the train upon stopping at stations, and prevent people from falling into or getting trapped in the PTI.
  6. Door obstruction fee, which would be charged when any passengers who prohibit the train doors (or PEDs) from closing. A fee could influence customer behavior and reduce the delays caused by customers rushing onto trains as the doors are closing. Two means of implementing this system are discussed from a non-technical standpoint, one being a camera based identification system, the other being Oyster card based.
  7. An accessibility card that would be available for riders with disabilities (visible or invisible) who require assistance to navigate around the Underground. This card would be a specially identifiable Oyster card that would notify the system whenever someone with it enters the station, so that station staff can provide assistance immediately.
  8. Further investigation of the effectiveness of signs as a focused study or project. The team found from data analysis that there are different perspectives on the provision of signs throughout stations. From the surveys, the team learned that a majority of passengers are satisfied with the provision of information but from the interviews with senior Jubilee Line staff the team learned that there are conflicting opinions on whether the Underground needs more signs or less signs. In order to determine which opinion is valid, the team suggest a study be performed on the distribution and optimization of signs across the Underground network. This study could include the design and placement of signs on the line.


Some of the recommendations are depicted in Figure 2 below.


Figure 2. Recommendations. Top Left: Visualization of Triple Pole. Top Right: Visualization of Platform Markings. Bottom Left: Photograph of Metal Railings


In conclusion, the team’s data analysis has led to two overarching factors that can improve the reliability of the Jubilee Line; customer behavior and modernization. As a long-term means of improving reliability, further modernization of the Jubilee Line would be the best course of action. It would improve customer satisfaction and behavior through the safety and punctuality benefits of PEDs and new train stock, and because of passenger’s preference for modern renovated stations. This would of course be the costliest approach, as any station construction or renovation or addition of new train stock would be much more expensive than the more cost effective reliability improvement recommendations outlined in this report. Regardless, the team learned that both ends of the Jubilee Line management believe that positively influencing customer behavior is currently the best way to improve service reliability. Based on the team’s findings, they believe that any future modernization plans will be more effective if the customer behavior is dealt with beforehand. Hence, it is imperative for London Underground to continue the current plans for modernization and improving signage being made on the Jubilee Line, and to do so across the entire network in order to further the growth of London as a global metropolis.