ACCORDING to the Department for Transport's (DfT) Long Term Passenger Rolling Stock Strategy Britain's passenger fleet is forecast to grow by between 53% and 99% over the next 30 years, and with the extension of electrification, it is estimated that between 13,000 and 19,000 new EMU vehicles will be required by 2044. Around 3050 vehicles will be delivered between 2015 and 2019 representing a capital investment of around £5bn.

As well as the replacement of older vehicles, the fleet needs to grow to accommodate rising passenger numbers, and rolling stock shortages are already a problem for many franchises. Indeed, it is clear that new-build cannot meet the short-term need for new trains, meaning older trains are still needed by operators.

When it comes to the residual British Rail fleet, which predates privatisation in 1994, vehicle owners face another dilemma. All vehicles remaining in passenger use on the network after 2020 must comply with Rail Vehicle Accessibility Regulations 2010 (RVAR), which require the installation of accessible toilets and other potentially costly modifications to vehicles that will be more than 25 years old.

All this is happening at a time of flux in the franchising system, with new contracts due to be awarded for 10 of the 16 passenger franchises before the end of the decade. With government departments facing constricted budgets, the specifications for these franchises demand better value for money as well as extra capacity.

This combination of factors has reinvigorated the market for rolling stock refurbishment. "We are entering a stable environment with new franchises in place which helps to create the conditions for investment in rolling stock," Mr Tim Burleigh, relationship development manager for leasing company Eversholt Rail told delegates at the Rail Vehicle Engineering conference and exhibition in Derby on October 8. "Our enhancement policy is market-driven and existing trains can be upgraded faster than new trains can be delivered. Financial constraints on the industry are likely to result in a blend of new build and upgrading in the future."

Eversholt's flagship upgrading project is the £60m Renatus programme, which involves modernising 30 four-car class 321 EMUs currently leased by Abellio Greater Anglia (AGA) for services from London Liverpool Street to Essex and Suffolk. The work, which will be carried out by Wabtec, includes equipping the trains with new air-conditioning and heating, new seating, Wi-Fi, accessible toilets, power sockets, energy-efficient lighting, and renewal of interior surfaces. The first train will be completed by Spring 2016.

Eversholt has gathered feedback from around 2500 passengers as well as cleaning and maintenance staff, on a demonstrator train, which operated in regular service with AGA. This feedback has fed into the final specification for the Renatus fleet.

The class 321 demonstrator has now been equipped with ac traction motors, new auxiliary systems and new braking systems by Vossloh Kiepe and testing is due to begin this month. Eversholt says it is investing £5.5m in this pilot retractioning project.

Other innovative projects seeking to satisfy the demand for additional rolling stock with low lease charges include Vivarail's D-Train, which involves rebuilding redundant London Underground D-Stock trains as DMUs and Porterbrook's 144e Pacer DMU upgrade, which claims to offer an RVAR-compliant train with a "transformed passenger experience" for around a third of the monthly lease costs of a new train.

Despite the advantages of refurbishment, Burleigh notes that new-build often remains a compelling option. "There is real competition from new-build and it's hard to take a long-term view of the life of the asset," he explains.

However, not all operators are happy with the new-build product and Mr Tim Sayer, engineering director for East Midlands Trains, told delegates that new trains often fall short of both operator and passenger expectations.

"Fleet reliability is better than it was 10 or 20 years ago but we have a long way to go before we can take rolling stock reliability out of consideration," he says. "In road haulage or shipping the reliability of equipment is no longer a key driver of the business and it is taken for granted that new stuff works - that is not the case in the rail industry. New trains are disproportionately expensive considering the technology on offer. Passengers do not want to spend 20 minutes debugging the reservation system, they do want to plug their device into a power point and access Wi-Fi. Unless we bridge the passenger expectation gap we will fail."

Sayer argues that the rail industry is still fixated on the initial capital cost of new rolling stock and is failing to take a life-cycle approach to procurement, considering both ease of maintenance and technical adaptability - a key factor for an asset with a 30-year design life. He notes that Project Thor, a proposal to convert Bombardier Voyager and Meridian inter-city DMUs to bi-mode trains by inserting a new-build pantograph car, was abandoned because the cost of conversion was 80% of the cost of a new train. Sayer contrasts this with the Royal Navy's new type 45 destroyer, "a ship built over a long period of time, thinking about the needs of the Navy 10-15 years in the future." These vessels are designed to enable lengthening with extra hull sections and "insertion of technology has been considered at every stage."

Sayer believes suppliers often fail to understand the needs of operators, and that there are too many barriers for entry into rail for suppliers from other industries, stifling innovation and competition. "Let's learn from other industries and take a punt," he concludes. "There's too much of an attitude that we can pass all this cost onto the end customer, and that's the last thing we want."