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| Defensive driving rules and differential speed limits 18/07/2015 at 20:08 #74359 | |
Jan
906 posts |
I have a suspicion that defensive driving rules don't account for non-standard differential speed limits. To give an example from LTS, I've just had a train for Shoeburyness platform 3 approach signal 353 - which is approach controlled for that route - at a speed of 16 mph, i.e. approximately a third of 50 mph. As the speed limit for that section of track is 50/MU 75, it seems like the defensive driving module isn't taking non-standard differential speed limits into account, otherwise the train could have been going at 25 mph. Two million people attempt to use Birmingham's magnificent rail network every year, with just over a million of them managing to get further than Smethwick. Last edited: 18/07/2015 at 21:22 by Jan Log in to reply |
| Defensive driving rules and differential speed limits 19/07/2015 at 08:54 #74362 | |
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Noisynoel
989 posts |
Okay, this begs a couple of questions. Which timetable, does the train type have DMU ticked, are defensive driving rules set up & correct, is the sim programed with the correct speeds in the first place? Any one of those would cause the train to use the 50 instead of the 75
Noisynoel Log in to reply |
| Defensive driving rules and differential speed limits 19/07/2015 at 15:51 #74363 | |
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Jan
906 posts |
Okay, to answer that: 1. I'm using the modified default timetable from this forum post. 2. All c2c trains are correctly marked as EMU. 3. The defensive driving rules in that timetable are set up as follows: For line speeds above 20 mph, reduce speed to 67 % for YY and to 33 % for Y. I've done another test with a down ECS train in the Chalkwell/Westcliff area, where according to the sectional appendix the speed limit is 50/MU 65. When running on unrestricted aspects, the train is going at 60 mph, so it seems the sim doesn't have that speed limit quite correct, but in any case it's faster than the non-MU speed limit. Just to make sure, I've edited the train and removed the EMU speed class entry, after which it's doing only 50 mph as expected. When running on double yellows with the EMU speed class active, the train slows to 33 mph, i.e. 67 % of 50 mph, and when running on single yellows, it slows down to 16 mph, i.e. 33 % of 50 mph. It also seems that something weird is going on with the check for the minimum linespeed for which the defensive driving rules should apply. I've tested with trains running on restrictive aspects between Chalkwell and Southend East and obtained the following results - I hope I've got the speed limits as present within the sim right: 50/MU 60: rules apply (Chalkwell/Westcliff) 35/MU 50: rules don't apply 35/MU 60: rules don't apply (Southend Central) 40/MU 60: rules don't apply 40/MU 70: rules don't apply 50/MU 70: rules apply (Southend East) How that relates to the minimum speed of 20 mph for that set of defensive driving rules I have no idea. On a side note, during testing, I've found some other speed limits that don't correspond to the values given in the sectional appendix. To sum it up:
Basically the non-MU speed limits look correct, but the MU speed limits have some inaccuracies. There are probably some other errors like that lurking out there (e.g in the up direction), but I didn't specifically look for them. Two million people attempt to use Birmingham's magnificent rail network every year, with just over a million of them managing to get further than Smethwick. Last edited: 19/07/2015 at 16:16 by Jan Log in to reply |
| Defensive driving rules and differential speed limits 19/07/2015 at 23:39 #74372 | |
GeoffM
6377 posts |
Thanks, I'll check. Just to add though, there were discrepancies found between the SA and the scheme plans during development. There may also have been minor adjustments over the years (which may also explain the SA and scheme plans being out of kilter) by 5-10mph. Long term I understand they want 100mph running on the straighter bits, much of Barking to Benfleet maybe. That'll create some interesting timetable conflictions with faster trains catching up with stopping ones a bit quicker! SimSig Boss Last edited: 19/07/2015 at 23:40 by GeoffM Log in to reply |
| Defensive driving rules and differential speed limits 20/07/2015 at 10:36 #74381 | |
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Jan
906 posts |
Thanks for the explanation, that clears that up then. So extrapolating from that section I've looked at, it seems that they might have fiddled with the MU speeds in order to try and optimise them, but left the non-MU speeds alone, because those affect only infrastructure trains and the odd freight train to Shoeburyness MOD.
Two million people attempt to use Birmingham's magnificent rail network every year, with just over a million of them managing to get further than Smethwick. Last edited: 20/07/2015 at 10:43 by Jan Log in to reply |