Vehicle Weight – Maintenance Implications
According to research by Robin Jones and Brian Sharpe on behalf of Heritage Railway Magazine, the closure of many of Britain’s branch lines 30-40 years ago was decided upon on the basis of costs using factors from the year 1961 as a base line. As a result, the costs actually applied were those associated with the most common rolling stock at the time, railway carriages pulled by a steam locomotive. The locomotives in particular, with their heavily loaded driving wheels, applied forces to the permanent way at joints between rails and at curves as if being repeatedly hit by a sledge hammer. Under such treatment the railway requires frequent maintenance attention, whereas when a light vehicle runs, the damage to the track is imperceptible.

This is because the axle of a heavy locomotive applies five times more weight than that of a light passenger vehicle and, in a dynamic situation, the wear and tear multiplies up. The difference is as great as that between being hit by a snowball or a stone. The parts of a railway which are most expensive to maintain are brick viaducts which are particularly vulnerable to constant hammering of heavy vehicles. Labour productivity is a further issue. A small loco-hauled train requires a crew of three and line side staff for signalling and to operate point work to enable the locomotive to ‘run round’ at the ends of the journey. The two person crew on a tram-sized railbus, meanwhile, can operate without trackside support if the vehicle can be driven from both ends.


Opportunity Missed
Rolling stock engineers were aware of these factors and had begun showing how it might be possible to completely transform the operating and maintenance economics of rural branch line using light diesel units. On the quietest branches, railbuses, weighing as little as 11 tonnes, would operate in place of trains. However, financially-trained but technically-challenged decision makers at the time disregarded such opportunities for bringing down costs. Railways which could have lived on were closed, as if the costs associated with steam-hauled trains would continue to be incurred.

Light railcars and railbuses were never made in sufficient numbers to optimise design and efficiency of manufacture. They arrived on the British railway system in response to special circumstances over virtually the same span of years which saw thousands of trams playing a crucial role in suburban transport in the first half of the last century and now in the present day. It must be noted that such is the cultural divide between British railways and tramways, there is a surprising absence of technology transfer or even sharing of experience between the two modes of small vehicle. The railbuses of the time were never trams running on railways, but bus bodywork placed on light freight chassis.


Technology Transfer
Experience, however, was shared to better effect in Europe and America. Fast, cross country streetcar lines “Interurbans” thrived in the United States until deliberately bought out and closed by United City Lines Inc, a company whose shareholders comprised Firestone Tyres, Gulf Oil and General Motors. Most of today’s ‘Supertrams’ and electric suburban railways derive their main features from an American streetcar model developed in 1933 which was capable of 80mph.

PPM’s ‘small is beautiful’ contribution in the last decade of the 20th century has been to rationalise the design and performance attributes between the two modes so that 90% of our railcar concept is applicable to the tram and vice versa. Our antecedents are the BR lightweight railbuses and the superb 2 axle Sheffield trams of the 1950s and the excellent coachwork of contemporary buses of 2003.


Light vs Heavy on Suburban Lines
It could be argued that a tram is a laterally thought out suburban train overcoming point by point all of the disadvantages associated with suburban railway trains. These disadvantages are:

  • Relatively poor acceleration and slow braking due to their weight, usually over 100 tonnes for a small three carriage ‘dmu’. Slow acceleration restricts the number of stopping places practicable to maintain line capacity. (Trams can accelerate as quickly as a road vehicle and have excellent brakes.)
  • The braking systems of trains are not assumed to be sufficient for drivers to stop within ‘line of sight.’ Services are therefore separated by set time intervals and level crossings have to be protected by signals. (Trams can run at any frequency required, ‘nose-to-tail’ even.)
  • Points of embarking passengers have to be built as ‘stations’ with high platforms, fencing and frequently underground passageways and bridges for passengers to cross the line. (Tramway tracks are fully available to pedestrians to walk over.)
  • The signalling and track circuits which are usually required make the railway more labour-and maintenance-intensive. (On tramways the vehicles can operate by line-of-sight under control of their drivers.)
  • Heavily engineered components such as engines, gearboxes and wheelsets are needed to propel heavy rail vehicles. These need the special heavy lifting equipment of a rail maintenance depot for mechanical support. (It is technically possible for a tram–sized vehicle to be maintained in a small automotive style workshop with only a modest amount of equipment.)
  • For a railway vehicle, a gradient of 1 in 100 is considered steep and 1 in 50 very steep, so railways cope with land contours by using cuttings, embankments, tunnels and viaducts. Trams, meanwhile, regularly climb gradients of 1 in 15, typical of roads. Tram lines conform to contours rather than creating near level alignments. The huge civil engineering costs of construction is the principal disadvantage of heavy railways.

Over the long history of railways in Britain there were few examples of attempts to apply tram technologies on suburban railways until Manchester Metrolink where, as often quoted by Transport Minister John Spellar, conversion of a single commuter rail line increased patronage so much that it now carries more people than all 13 remaining suburban railway services into the city. Trams are now accepted as the key to shifting regular journeys from private to public transport.


Trams on Railways
In Switzerland to this day, clean, modern lightweight trains link rural towns and villages while running on street like trams in suburban parts of St Gallen and other centres. In Karlsruhe, Germany, trams run on street in the city centre then disperse into the countryside on conventional railway lines.


Five Eras of Railbuses and Light Railcars
One of several types of railbuses introduced in the 1920s transferring crude ‘bone-shaker’ bus technology to rail virtually unmodified. The capacity of the paired set was typically 36 seats. Most of these units ran on lines built under Light Railway legislation aimed to make railways more affordable in rural areas. The vision was lost in the excitement of the new automotive age which took over between the wars.
44 seat, wind-tunnel tested, attractively styled Hardy/AEC Railcar, 40 of which were built for the Great Western Railway in the 1930s. These railcars provided express interurban services on routes such as Birmingham-Cardiff where passenger flows did not justify running larger trains.
40 seat lightweight railbus of the 1950s designed to save some of the rural lines which Beeching closed anyway.
1980s British Rail/Leyland National 50 seat railbus, never adopted in original form but was ‘stretched’ to create the 140 series ‘Pacer’ utility multiple units still in widespread use.
A PPM 50 Light Railcar, a tram type rail vehicle which could be an important tool in the localisation of quiet rural lines.


Community Railways, a New Vision
The Association of Community Rail Partnerships, brainchild of Dr Paul Salveson and colleagues, has over a number of years been gathering support for a concept somewhat akin to that conceived by the advocates of light railways in the late Victorian era. ACoRP’s powerful advocacy has now resulted in a decision by government to initiate a pilot project in North Yorkshire. The essence of the project is to explore the benefits of devolving rural railway management away from the complex multi-company arrangements of the rest of the privatised national industry.

A new company, the Esk Valley Railway Development Company, will take over the operation of the loss-making at presently lightly used branch line from Whitby to Middlesborough. The plan is to increase services from four trains a day to one every two hours connecting to services on the preserved North Yorks Moors Railway to Pickering. The Strategic Rail Authority are supportive, recognising the economic impact of ‘standards creep’ as ever-more onerous rules necessarily in force on main trunk lines affect the economics of slower, simpler branches of the network.

Local authorities, community groups and volunteers will be encouraged to lend a hand in running the Esk Valley line, making it a kind of hybrid between a heritage railway and a national line. Although the Esk Valley operators will use conventional rolling stock, Paul Salveson and colleagues are well aware and supportive of the need for the PPM development which they see applicable to other projects of this kind in rural areas.

Page last updated: 23 April, 2003
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