The Anonymous Widower

A Numerical Analysis Of Great Northern’s New Class 717 Trains

Great Northern is replacing forty-four Class 313 trains of three-cars with twenty-five Class 717 trains of six-cars to work all services out of Moorgate station and probably some out of Kings Cross station.

So 132 carriages are being replaced with 150, which increases the space by about six percent.

But how many trains are actually needed to work the various routes?

Moorgate To Welwyn Garden City

Moorgate to Welwyn Garden City is a 3 trains per hour (tph) service.

The trip takes 51 minutes, so this means a train can go from Welwyn Garden City to Moorgate and back in under two hours.

We get the number of trains as follows.

• 3 tph needs 6 trains.
• 4 tph needs 8 trains.
• 6 tph needs 12 trains.

Moorgate To Hertford North

Moorgate to Hertford North is a 3 tph service.

,The trip takes 50 minutes, so the needs for the Hertford North are as follows.

• 3 tph needs 6 trains.
• 4 tph needs 8 trains.
• 6 tph needs 12 trains.

Moorgate To Letchworth Garden City

As the extended train to Letrhworth Garden City takes 25 minutes from Hertford North, this probably means that the trains needed for the extended service are as follows.

• 1 extended tph needs another train.
• 2 extended tph needs another 2 trains.

Total Trains On The Northern City Line

So this gives the following totals for trains on the Northern City line.

• 3 tph on each route with 1 tph to Letchworth Garden City needs 13 trains.
• 4 tph on each route with 1 tph to Letchworth Garden City needs 17 trains.
• 4 tph on each route with 2 tph to Letchworth Garden City needs 18 trains.
• 6 tph on each route with 1 tph to Letchworth Garden City needs 25 trains.

I don’t think we’ll see six tph on both routes, as that could be too many trains for the tunnel to Moorgate, which probably has a capacity of less than 10 tph.

Kings Cross To Foxton

In addition, Great Northern run an hourly  service between Kings Cross and Foxton, which could use the new trains.

The service takes 75 minutes.

So as the service actually starts and finishes at Cambridge, this probably means the round trip is three hours, so the service will require the following number of trains.

• 1 tph would require 3 trains.
• 2 tph would require 6 trains.

Conclusion

The mathematics say to me, that the number of trains ordered is enough for the following services.

• 4 tph from Moorgate to Welwyn Garden City – 8 trains
• 4 tph from Moorgate to Hertford North – 8 trains
• 2 tph extended from Hertford North to Letchworth Garden City. – 2 trains
• 2 tph from Kings Cross to Foxton and Cambridge – 6 trains.

Although this doesn’t mean that this will be the service pattern.

It’s just if Great Northern wanted to go from 3 tph to 4 tph on the Northern City routes and increase other services, they have ordered enough trains.

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September 12, 2016 - Posted by AnonW | Transport/Travel | Class 717 Train, Hertford Loop Line, Moorgate Station, Northern City Line, Trains