Semaphore signal gantry at Surendranagar Jn. March 11, 2011. (Paul Bigland)

Semaphore signal at Surendranagar Jn. March 11, 2011. (Paul Bigland)

Lower quadrant semaphore signals at Viramgam Junction. March 11, 2011. (Paul Bigland)

Lower quadrant semaphore signals at Viramgam Junction. March 11, 2011. (Paul Bigland)

Lower quadrant semaphore signals at Viramgam Junction. March 11, 2011. (Paul Bigland)

A pair of Neale's ball token instruments at Ghunsore. Photo by Sanket Gosavi, 2011. (Gallery Administrator)

A Neale's ball token instrument by Kyosan, Ltd., from the Khem Karan station, which somehow ended up in Pakistan's Railway Heritage Museum at Golra. Photo by Mr Iqbal Samad Khan, ex-GM of PR, 2005. (Gallery Administrator)

Tokenless block instrument by S&T Workshop, Podanur. Photo from S&T Workshop. (Gallery Administrator)

Sykes Lock and Block instrument from about 1897. This particular example is not from India, but identical Sykes Lock and Block instruments were used quite widely in India. Photo copyright belongs to the Science and Society Picture Library, UK. Photograph

Neale's tablet token block instrument, manufactured by the Westinghouse Brake and Signal Co. This particular example is not from India but these instruments were widely used in India. This one is from the Thai-Burma railway. Photo by Sir Ross BA, 2011. Cr

Line diagram of Neale's Ball Token Instrument. Scanned from SCR signalling materials. Scan provided by Apurva Bahadur. (Gallery Administrator)

Line diagram of Neale's Tablet Token Instrument. Scanned from SCR signalling materials. Scan provided by Apurva Bahadur. (Gallery Administrator)

Line diagram of Neale's Voucher Instrument. Scanned from SCR signalling materials. Scan provided by Apurva Bahadur. (Gallery Administrator)

Line drawing of Webb and Thomson electric staff single line block instrument. Scanned from SCR signalling material. Scan provided by Apurva Bahadur. (Note: Diagram is linked from single-line block instruments article.) ()