Home

1. Corporate Induction
2. Railtrack Zone
3. Electrification and Plant Appreciation
4. Plant Maintenance
5. Maintenance Planning
6. Track Design
• Estimating
• Surveying
• Basic Design
• Curves
• Deficiancy and Cant
• Gauging
• Track Inspection
• Clearance analysis
• Center and End Throw
• Buffer Locking
• Stepping Distances
• Design Proceedure
• Evaluation
7. Vehicle Systems Design
8. Manufacturing
9. Track Renewals
10. Electrification Testing and Commisioning
11. Electrification Design and Construction
12. Overhead Line and Track Renewals
13. Career Directed Experience
 
14. Links

Clearance Analysis

Another project currently underway is route clearance of both the ECML and the WCML. This incorporates train movements and minimum clearance distances. The kind of clearance being analysed is signal overlap, centre throw / end throw and buffer locking. The aim of the project is to identify areas where these circumstances may occur, and to see if the area can be re-designed or slued. The above circumstances can cause train collisions. Signal Overlap

Track circuits are used on the railway network to monitor train positions. A train completes a low voltage circuit so that the signaller knows the position of the train. These track circuits are placed in accordance with signals, but signal overlap is usually incorporated.

Signal overlap can be best described as a region of safety in the event of a SPAD. That is, the track circuit aligned with a relevant signal, starts/ends after the signal. The following diagram best illustrates this.

Signal overlap is typically set to a distance of 183 m

In the worst case, the track circuit can be adjacent to the signal, therefore creating no signal overlap. This can create a problem, since a train stopping at a red aspect will have its wheels just before the start of the next track circuit. This may leave the nose cone of the train protruding over the next track circuit. Although this would not cause a signalling overrun, it may be in risk of collision from other traction. Fig. XXXX highlights this.

This is of particular interest where a turnout may exist.

Curve Analysis

I was also introduced to the ECML curve analysis study. This is a study on all curves between London Kings Cross and Edinburgh. The idea for undertaking this study is to determine where line speeds can be increased and to also identify curves on the ECML which are non complient.

Since the study is already underway, I was shown some results of the curve analyses. In some places along the line, curves exceed their maximum cant.

The maximum cant allowance is 110mm for jointed track and 150mm for Continuously Welded Track (CWR).

As a result of finding this, either the track or the line speed will have to be changed.

But what information is used to analyse every curve on the ECML? Data from the High Speed Track Recording Coach (HSTRC)2 is used as well as old versine design drawings. The old design drawings can offer a basic idea to the track, but over time track does move. The HSTRC printouts can verify as to how much the track as moved. This is because the printouts are a lot more recent than the design drawings.

Another reason for analysing the route is to ensure that all relevant curves are lubricated. Since some of the curves are not at the radius they were designed, lubrication may be needed, especially if the radius had decreased. The TDM states that all track with a radius of between 500m and 200m has to be lubricated. There are no curves less than 500m radius

So apart from realising where rail lubrication might be needed, and looking for cant exceedencies, what is the point in trying to increase line speed?

It may seem pointless in increasing the line speed by 5 mph over a one mile section as this would reduce the journey time by only a couple of seconds. However, if this were to be done at every possible section for the entire ECML, then maybe 15 minutes would be taken off a journey time between Scotland and London. This is very desirable, by both the TOCs and Railtrack. But is it economically justifiable in carrying out this study. Corus are being paid to conduct the study, and if it is successful, the journey between Edinburgh and London can be reduced. If shorter journey times are a result of the study, would this not mean that trains would run to a tighter schedule? That is, for example, stopping at one red aspect would delay the train behind. Compensation would have to be paid, and since it is a TOC on TOC delay, Railtrack would be liable for the compenstion.