Transport for London

“The solution that TelecityGroup and TfL Group Marketing Operations devised for the Journey Planner site has produced excellent results. The performance of the site has been noticeably improved and the user experience is excellent. Feedback from customers has been very positive as well.”

David Coppins, Group Marketing Operations, Technical Manager, Transport for London.

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Introduction

Transport for London (TfL) was set up in 2000 to take central responsibility for London’s public transport services including London Buses, London Underground, Docklands Light Railway (DLR) and the management of Croydon Tramlink and London River Services.

Additionally, it is responsible for a 580km network of main roads – including the management of the central London Congestion Charging scheme - and London’s 4,600 traffic lights. More recently TfL has taken responsibility for the regulation of London’s taxis and private hire services.

TfL also promotes a range of walking and cycling initiatives across the capital and co-ordinates schemes for transport users with impaired mobility.

Each day over 30 million journeys are made in the capital. To make these as straightforward and trouble free as possible, and to provide details of all of the services under its remit, TfL launched its Journey Planner website www.journeyplanner.org in August 2002.

What started as simple pages containing maps and timetables is now a complex, real-time guide to business and leisure travel in the capital. In addition to up-to-the minute service and traffic updates, TfL also offers customers the option of receiving travel updates via mobile, SMS and interactive TV services.

Keeping the service up and running

With so many people relying on the site it is vital that the website is available 24 hours a day. It also has to be able to handle sudden and prolonged peaks in traffic, as were experienced during the New Year’s Eve industrial action for example. On December 31 2005, the Journey Planner site was visited by 100% more customers than it had been in the previous days.

From the launch of the site in 2002, TfL made the decision to outsource the hosting and management of the website to TelecityGroup, a leading managed hosting and security services provider.

“Initially, the service was hosted on five web servers, located in TelecityGroup’ London hosting centre. The requirement soon grew to 15 as the number of site queries rocketed – from 5.5 million in January 2003 to 28 million in January 2006 – and the breadth and complexity of the content increased,” said David Coppins, Group Marketing Operations, Technical Manager, Transport for London.

Traffic planning

In December 2005, the decision was made by TfL Group Marketing Operations to once again review the hosting options. To remain useful to passengers, Journey Planner needs not only to be up and running, but to deliver searches quickly and provide updates in real-time.

This rapid increase in capacity had to be addressed and future projected monthly increases in traffic, as well as the unpredictable spikes and peaks, had to be factored in. New applications are also scheduled for 2006, including a road route planner and an increase in languages from the current four to 12. The impact of these on the web hosting infrastructure also had to be considered.

David said: “We were experiencing a huge growth in traffic and we needed to ensure the site’s performance could cope with this increase in demand. We recognised that we needed to conduct a complete review of the infrastructure and decided that the best way to do this would be to work in partnership with our hosting partner TelecityGroup. The immediate solution would have been to add new web servers to keep up with demand. However, after discussing this with TelecityGroup, we concluded this was not the most effective option from a system efficiency or investment perspective.”

With this in mind, TfL Group Marketing Operations and TelecityGroup devised a dual approach to the issue. TfL’s existing hardware was upgraded to HP Opteron servers because of their proven performance capabilities. In fact, during testing, TelecityGroup found that the Opteron server was nearly three times faster in comparison to the existing hardware but with less power consumption requirements. This meant that TfL could enhance performance by 300% while reducing the amount of servers it required to run the site by 33%.

To optimise performance further, TelecityGroup installed Citrix Netscaler technology to reduce pressure on the CPU processing power by offloading much of the communication, security and physical content delivery work that normally burdens a web server infrastructure.

Immediately after implementation the average CPU usage reduced from 40% to 2% and the site performance was noticeably enhanced; page delivery times reduced by up to eight times and the Journey Planner home page was opening in an average 0.6 seconds, down from 1.5. Additionally, burstable bandwidth removed the issue of traffic peaks and the option to increase capacity permanently means TfL can rollout its proposed services as soon as it wants.

David continued: “The solution that TelecityGroup and TfL Group Marketing Operations devised for the Journey Planner site has produced excellent results. The performance of the site has been noticeably improved and the user experience is excellent. Feedback from customers has been very positive as well.”

How the technology works

By installing NetScaler technology, TelecityGroup was able to combine the traditional data centre features and functions – load balancing, caching, compression, SSL acceleration, attack defence and SSL VPN - into a single network appliance that sits between the web browser and the web server.

As with most transactional websites, TfL’s front-end servers divide their time between managing the thousands of web browser connections and executing application code to create responses. On a typical day, TfL has 2,000 concurrent users, however, incredibly, the implementation of Netscaler managed to consolidate this into just 50 back-end web server sessions. This means the servers can spend much more of their CPU time responding to application requests, resulting in better response times and higher throughput.

Because the Netscaler sits between the end user and the web servers it can also act as a cache. TelecityGroup configured the units to cache all HTML, Images, PDFs, Javascript, XML and CSS. As a result, up to 40% of all server requests are delivered from the cache without even reaching the servers. Not only does this improve end user experience but it also reduced the thousands of HTTP Get requests to the web servers.

Combined with page compression (up to 50% of the original size) and connection optimisation, TelecityGroup has been able to speed up the transmission of data to end users and reduce TfL’s bandwidth requirements.

Paul Court, Technical Services Director, TelecityGroup UK explained: “Much of the information requested on the TfL site is of a repetitive nature, for example gifs and maps. By removing this burden from the web server infrastructure we have instantly optimised the efficiency of TfL’s server investment and removed the need to invest in more hardware.”

The result

The end result for TfL is a decrease in user request times from 10 seconds to 1-2 seconds per transactional page. This represents an improvement in response times for passengers of nearly 1000%, without the need for TfL to increase server hardware, power or data centre space.

Interesting facts about travel in London

Every day, about 30 million journeys are taken in Greater London:

• 6.3 million by bus
• 3 million by Tube
• 1.4 million by rail
• 150,000 on the DLR
  
• 11 million by car or motorcycle
  
• 7 million on foot
  
• 333,000 by bicycle
  

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