Faster times to Slough

The reality of the laws of physics has been recognised, with the poorer performance of the Class 800/0s when propelled by their diesel engines compared with 25kV ( RAIL 842).

The 1½ minutes difference for the Paddington to Slough times clearly points to the Paddington to Reading (start to stop) time being at least three minutes slower - a 12% deterioration!

What is also apparent from the Railway Performance Society’s graphic is how the restriction to 50mph over the first two miles also hinders performance.

This speed restriction was imposed after the Ladbroke Grove accident, as a means of dealing with the sighting of signals located on overhead gantries and partially obscured by the 25kV knitting.

However, the Down Fast line is the left-most track on the formation, and so has most of its signals on straight posts once past Royal Oak. With signal aspects well below the wires, the sighting is good, and I can see no practical reason why risk assessment should not offer a permitted speed of at least 80mph between mileposts 1 and 2 (it was previously 90100mph) on this particular line.

The 45-second advantage to all trains on this line would make it possible to reliably schedule Paddington to Reading in 21 or 22 minutes for electric services. When the earlier permitted speeds applied, I once recorded an HST passing milepost 4 in four minutes from the start out of Platform 2, and the stop at Reading was often achieved in about 22 minutes.

Obviously the ‘800s’ will normally operate on electric power in this area, but the loss of performance will clearly be significant beyond the currently proposed western limits of the overhead power supply - frittering away the benefits gained. Jim Wheeler, Surbiton