Is the Heathrow Express a viable, worthwhile service?

[mangyiscute]

Imo the ideal is once Didcot to Oxford is electrified, the HeX trains are used to run 2tph London to Oxford 8 car 387s (making it 3tph alongside the cotswold line service) since Oxford desperately needs this extra capacity, with a few spare IETs going to increase capacity elsewhere.

 

[stevieinselby]

Could you elaborate on what these are (presumably in addition to 'long-distance' services, above)?

The obvious example is the Greenford branch, which used to have through services to Paddington but now terminates at West Ealing – and has seen passenger numbers crash as a result. If HEx was removed then those trains may be able to run through to Paddington again. Alternatively (or both) increase the frequency of Crossrail trains to Heathrow to replace the lost HEx services, making a more consistent service and with better connectivity.

 

[Kite159]

The obvious example is the Greenford branch, which used to have through services to Paddington but now terminates at West Ealing – and has seen passenger numbers crash as a result. If HEx was removed then those trains may be able to run through to Paddington again. Alternatively (or both) increase the frequency of Crossrail trains to Heathrow to replace the lost HEx services, making a more consistent service and with better connectivity.

Highly unlikely a half hourly 2 coach DMU will be allowed out onto the relief lines alongside the Elizabeth line services. Any paths freed up by removing Heathrow Express will be on the mains.

Especially as GWR will need to find another unit to provide a half hourly service

 

[Horizon22]

The obvious example is the Greenford branch, which used to have through services to Paddington but now terminates at West Ealing – and has seen passenger numbers crash as a result. If HEx was removed then those trains may be able to run through to Paddington again. Alternatively (or both) increase the frequency of Crossrail trains to Heathrow to replace the lost HEx services, making a more consistent service and with better connectivity.

No it's not obvious - the Greenford branch would run on the Relief lines and removing of HeX would open up path on the Main Lines.

The only branch this might benefit is the Windsor Branch, but using a Turbo on the Mains wouldn't be a much better use of capacity. I agree with @mangyiscute that if Oxford was electrified an EMU service there would definitely be beneficial, which should free up IETs for other work.

 

[BogiePicker]

Would the GWML be more efficiently used if the HEX 387s (and perhaps even the GWR 387s) ran to 125mph max? Do the 387s theoretically hold up the IETs? With modern traction motors, stock should have no problem quickly romping up to speed. 745s hit the ton in around a minute.

 

[JonathanH]

Would the GWML be more efficiently used if the HEX 387s (and perhaps even the GWR 387s) ran to 125mph max?

They aren't built to run at 125mph as they don't have suitable crumple zones, pointy noses etc.

Do the 387s theoretically hold up the IETs?

A 387 is two minutes slower to Reading on a non-stop service - 25 minutes versus 23 minutes, although IETs were once timed at 22 minutes rather than 23 minutes. As far as Airport Junction it doesn't really make a difference.

 

[mangyiscute]

I'd be very surprised if that would create any new paths, since there is such minimal difference, plus currently the non stop 387s (mainly just Newbury services) usually run just before or after the HeX and Slough to London services so the lower speed makes even less difference.

 

[zwk500]

Would the GWML be more efficiently used if the HEX 387s (and perhaps even the GWR 387s) ran to 125mph max? Do the 387s theoretically hold up the IETs? With modern traction motors, stock should have no problem quickly romping up to speed. 745s hit the ton in around a minute.

I'd be very surprised if that would create any new paths, since there is such minimal difference, plus currently the non stop 387s (mainly just Newbury services) usually run just before or after the HeX and Slough to London services so the lower speed makes even less difference.

In addition, 125 doesn't start until Ealing Broadway (src: OpenRailwayMap), so you only have 5.5 miles of the additional 25mph (Ealing Broadway is 5m56ch, Airport Junction (DM) 11m15ch, src: http://www.railwaycodes.org.uk/elrs/_mileages/m/mln1.shtm)
5.5 miles @ 100mph = 3 mins 18 secs
5.5 miles @ 125mph = 2 mins 39 secs.
So HEx running at 125mph saves 39 seconds total. Given how the SRTs are broken up on that section and once you add the 5% allowance, I'd be surprised if any of the SRTs changed at all.

 

[SynthD]

Presumably HEx won't have dedicated platforms at OOC so there will be no way of telling what train you used.

Heathrow to relief platforms at OOC will always (except Sundays) be Elizabeth line, and to main platforms will always be HEx. I hope HEx won’t be reimbursed for Sunday passengers paying lower fares.

 

[Stephen42]

In addition, 125 doesn't start until Ealing Broadway (src: OpenRailwayMap), so you only have 5.5 miles of the additional 25mph (Ealing Broadway is 5m56ch, Airport Junction (DM) 11m15ch, src: http://www.railwaycodes.org.uk/elrs/_mileages/m/mln1.shtm)
5.5 miles @ 100mph = 3 mins 18 secs
5.5 miles @ 125mph = 2 mins 39 secs.
So HEx running at 125mph saves 39 seconds total. Given how the SRTs are broken up on that section and once you add the 5% allowance, I'd be surprised if any of the SRTs changed at all.

The GWR and Heathrow Expresses class 387s are timed at 110mph rather than 100mph so the difference is even smaller.

 

[mangyiscute]

Heathrow to relief platforms at OOC will always (except Sundays) be Elizabeth line, and to main platforms will always be HEx. I hope HEx won’t be reimbursed for Sunday passengers paying lower fares.

Although will the relief and main platforms be behind separate gate lines, as that would make many interchanges unnecesarily cumbersome - especially considering these platforms will be adjacent, I would expect a way of getting between them without going through a gateline.

Looking at the current timetables, converting the HeX or GWR 387s to 125mph running would not create any extra paths, since the 387s are all timed to run consecutively meaning departures of them and 80xs can still be within 2-3 mins of each other.

 

[zwk500]

The GWR and Heathrow Expresses class 387s are timed at 110mph rather than 100mph so the difference is even smaller.

5.5 miles @ 100mph = 3 mins 18 secs
5.5 miles @ 110mph = 3 mins 00 secs
5.5 miles @ 125mph = 2 mins 39 secs

For completeness

 

[The Planner]

In addition, 125 doesn't start until Ealing Broadway (src: OpenRailwayMap), so you only have 5.5 miles of the additional 25mph (Ealing Broadway is 5m56ch, Airport Junction (DM) 11m15ch, src: http://www.railwaycodes.org.uk/elrs/_mileages/m/mln1.shtm)
5.5 miles @ 100mph = 3 mins 18 secs
5.5 miles @ 125mph = 2 mins 39 secs.
So HEx running at 125mph saves 39 seconds total. Given how the SRTs are broken up on that section and once you add the 5% allowance, I'd be surprised if any of the SRTs changed at all.

5% allowance?

 

[zwk500]

5% allowance?

May not be 5%, but the allowance above raw runtime that's included in SRT calculations.

 

[The Planner]

May not be 5%, but the allowance above raw runtime that's included in SRT calculations.

Shouldn't be any (unless its the wacky Southern way of incorporating box time), any rounding should cater for being cautious.

 

[MarkyT]

5.5 miles @ 100mph = 3 mins 18 secs
5.5 miles @ 110mph = 3 mins 00 secs
5.5 miles @ 125mph = 2 mins 39 secs

For completeness

On RTT, looking at a handful of mid-morning Down Main running times planned on Tuesday 23/04 from a standing start at Paddington, they all pass Heathrow Airport Junction between 8.5 and 9.5 minutes after departure, with the lower figure representing the best 80x times. The difference is around the margin between planning and technical signalling headways, so the lower top speed doesn't seem to practically affect pathing capacity much if at all over this fairly short stretch as long as the Electrostar turns off there or shortly afterward at Dolphin Junction onto the Reliefs. Even by Reading, the difference in timing for a non-stop run on the DM throughout is only two minutes, 23(80x) vs 25(387) minutes. I expect the Electrostars are a little more sprightly in acceleration in the lower speed ranges, being a lighter train geared more for stopping service, but the Hitachis will keep on accelerating for longer clearly. In practice I expect a Hitachi driver might ease off the throttle and coast a little if they see a double yellow a few signals ahead while still having plenty of time to react if they have to brake for a stop, but under normal conditions that restrictive aspect will quickly step up to green once the HEX has cleared the junction and ARS has reacted promptly to move the points and set the straight route. Now the driver will see only a series of greens ahead and can throttle up accordingly as necessary. Any time lost would be a few seconds at most.