wrote:

Does that part of LUL have AWS (I don't recall seeing it when I was
down there.)? If not, then whar sort of safety back up are SWT trains
using on that segment, lower speeds? AFAIK, SWT trains are not
equipped with tripcocks.

The answer is that the line is fitted with TPWS as well as the LUL trainstop
system. At each signal, there is a TPWS loop and a trainstop. The reason
for the 30 mph limit for National Rail trains is because of "power supply
difficulties". The voltage is 650V to accommodate the LU trains, rather
than the usual 750V for SWT.

(Info obtained by Googling for "East Putney AWS" which produced an unlikely
source, the November 2005 edition of the Newsletter of the Institution of
Railway Signal Engineers (Hong Kong Section). See page 17 at
http://www.irse.org.hk/chinese/newsl...ber%202005.pdf )

--
Richard J.
(to email me, swop 'uk' and 'yon' in address)