Northern Line - Ride Quality (1)

Meeting: 
MQT on 2015-03-25
Session date: 
March 25, 2015
Reference: 
2015/0946
Question By: 
Andrew Dismore
Organisation: 
Labour Group
Asked Of: 
The Mayor
Category: 

Question

A  constituent has  complained about ride quality, to do with the uncomfortable and never-ending changes between acceleration and braking, rather than  track alignment or train suspensions. He asks are trains attempting to run at a computerised predefined speed at each instant of travel? For a typical section of track away from stations, how wide, in km/hour, is the allowable speed range, such that above it the brakes are applied, and below it the accelerator? In this middle range, do the trains just coast or at least are on purely nominal base power?

Answer

Answer for Northern Line - Ride Quality (1)

Answer for Northern Line - Ride Quality (1)

Answered By: 
The Mayor

The new signalling system on the Northern line is now allowing London Underground to deliver a much needed increase in capacity and train frequencies - especially during the busiest times. Since December 2014, there has been a 20 per cent increase in capacity through central London on the Northern line and increased train frequencies of up to 24 trains per hour on the Charing Cross branch and up to 26 trains per hour on the Bank branch.

In order to accommodate the increasing demand along the line, these frequencies will continue to increase incrementally in the coming years.

There is not one predefined speed at which trains will travel on the new signalling system. Trains accelerate as they leave the platform, coast once they reach their target speed, and brake as they enter a platform. The upper or lower limit of the period the train will coast at its target speed - up to 80 km per hour - is not fixed. It is also dependent on a number of factors, such as gradient. All of the system's actions are monitored, regulated and fit within an industry standard rate.

When the new signalling was first introduced, minor adjustments were made to the smoothness of the ride in order to achieve a balance of ride experience whilst achieving desired levels of trains per hour. If further adjustments are made, it would mean reducing train speed, thereby affecting the timetable.