THE LATEST report from the UK's National ERTMS Programme Team revealed on June 23 that plans to fit all lines where the speed exceeds 160 km/h by 2015 have been scrapped.

The new strategy sees development continuing, mainly on the single-track Cambrian lines in rural mid-Wales, but even that project has slipped by eight months in the last year and will not be ready to start evaluation until late 2008 (RG 6.04 p317).

Meanwhile, condition-based replacement of colourlight signalling installed in the 1960s and 1970s is expected to continue at least until 2011. The first section to be converted to ERTMS is now expected to be the Great Eastern main line. Work will start at the country end, reaching London's busy Liverpool Street commuter terminus by 2023.

This major policy change has been driven by two key considerations.

The first is that national fitment of the Train Protection & Warning System - completed in December 2003 - along with other measures to reduce the number of signals passed at danger, 'has already achieved a very substantial reduction in the risk to passengers of collisions', according to Strategic Rail Authority Chairman David Quarmby. The projected safety benefits of ERTMS are now less than one equivalent fatality a year, so the safety element in the overall business case is no longer significant.

The second is that there is no business case at all for installing ERTMS unless it avoids the cost of renewing lineside signals. Even then, there have to be significant capacity and performance benefits as well to lift the NPV curve above zero. It then becomes necessary to devise a programme for replacing or retrofitting trains that is compatible with the essentially random process of signalling becoming life-expired. The further that process can be stretched, the less retrofitting of trains not designed for ERTMS is necessary.

Another point stressed by Quarmby is that any ERTMS programme driven economically by signalling renewals has to be System D, which is UK terminology for Level 2 without lineside signals. A simplified version of Level 2 called System E will be used on rural lines, although the Cambrian trial now due to start in 2008 will be System D.

Quarmby observed that 'the pace of development across Europe carries on but it continues to be slower than expected, particularly for mixed-traffic railways.' There is no mixed-traffic route where System D is currently in use.

The earlier decision to give priority to installing ERTMS on trains and lines exceeding 160 km/h stemmed from reports into multiple-fatality collisions at Southall in 1997 and Ladbroke Grove in 1999. Both were caused by drivers passing signals at danger on the Great Western main line which, ironically, was fitted with full ATP although it was not in use on the trains involved.

Depending on braking performance, TPWS will stop most trains within the safety overlap beyond a red signal from 110 to 120 km/h. After the original programme was completed, critical signals on 200 km/h lines were retrofitted in 2004 with TPWS+, which can stop 160 km/h trains in the safety zone. Hence the decision to give priority to 200 km/h lines in earlier ERTMS programmes.

As our chart shows, the result of the latest policy change is that sections of the busiest 200 km/h inter-city routes, such as the West Coast and East Coast main lines, will not see the benefits of ERTMS throughout until 2038 and 2036 respectively. This is because the busiest southern section of the WCML is currently being resignalled, and the northern part of the ECML was resignalled in the late 1980s.