City road bug?

[rsdworker]

the present day city road in simtrans - 1950 to 2100's - seem have weight too low - 12t - even some buses can't run on 12t its shouldn't be happening - its should be at 16t as standard city roads

[jamespetts]

Do you know of any sources of real life British road weight restrictions? I think that I set the weight limits from information as to maximum allowable weights in reality; if you think that I had the wrong information, I should be grateful to know the correct information.

[rsdworker]

Do you know of any sources of real life British road weight restrictions? I think that I set the weight limits from information as to maximum allowable weights in reality; if you think that I had the wrong information, I should be grateful to know the correct information.

most roads in real life is 80t because heavy loads using but few exepctions - older bridges have weight limits - brick bridges often have weight limit (50t)

[jamespetts]

most roads in real life is 80t because heavy loads using but few exepctions - older bridges have weight limits - brick bridges often have weight limit (50t)

May I ask what the source is for that information? Also, is this axle load or total weight?

[rsdworker]

May I ask what the source is for that information? Also, is this axle load or total weight?

total weight i believe - because railways uses axle load while road weight is not limited to axle but total weight example lorry carrying Goods totalling 20t so the road weight would be 40t depnding on type of road - the older roads was limited to weight of transport that passes over
i am trying to find the soure

[jamespetts]

Simutrans-Experimental uses axle loads (except for bridges), so perhaps that is where the confusion arises?

[rsdworker]

Simutrans-Experimental uses axle loads (except for bridges), so perhaps that is where the confusion arises?

yeah that's could be because bridges uses total weight

[Junna]

most roads in real life is 80t

80t total load would be about 13-14 tonne axle load (assuming three-axled trailer unit).

Apropos of axle loads, a total digression, but... The Pennsylvania railway in America had these very heavy electric locomotives (the P5), which seemed to have had an axle load of 34.5 tonnes (!). How in the world can they have run - there's no mention anywhere of weight restriction above axle load of 30 tonnes, and those are using more robust concrete sleepers... Some unit were stored in Ohio somewhere, and when they attempted to move it, they tore up the sleepers and distorted the tracks; how did they get it there in the first place? I've never heard of any railway having 35 tonne axle load restriction.

[DrSuperGood]

The issue might be the busses are too heavy? Which busses specifically give this problem.

Road vehicle axel load is very different from rail vehicles. Rail vehicles it is the weight divided by number of wheels. Where as road vehicles it is based on contact surface area (as tyres deform under weight). Small modern cars might be light but they also have very thin and small tyres so should have reasonable axel load. Busses on the other hand use very thick tyres so despite being heavy should have much less axel load to model this. Trucks weigh even more but they have more than 4 tyres and some are even double (two tyres in parallel next to each other) so should be modelled as even less axel load. By this I mean in proportion to their weight over axel number.

It is possible the weight metric for the bus is correct but the axel load is computed incorrectly making it need tougher roads than it should. Road vehicle axel load should be based on contact surface area and not weight over number of wheels.

[jamespetts]

I have to say, I had not considered the contact surface area issue: that is an interesting point. The code does not account for this, just giving a single figure for "axle load". I am not quite sure how contact surface area would work in this connexion.

[Vladki]

Most busses have double tyres at the back axle. Maybe they could be counted as two axled.

Sent using recycled electrons.

[jamespetts]

Most busses have double tyres at the back axle. Maybe they could be counted as two axled.

Sent using recycled electrons.

That applies to a lot of heavy vehicles; but a lot of roads do indeed have specific "axle load" limits; how are these computed?

[Spenk009]

A german article (http://www.lto.de/recht/hintergruende/h/schwertransporte-rechtliche-leitplanken-fuer-die-titanen-der-strasse/) suggests:

Für die Berechnung des Gewichts der Zugmaschine multipliziert man die Achszahl mit 9 t. Bei einem 4-Achser kommt man dann auf 36 Tonnen (tatsächlich sind's meist 35 t). Beim Anhänger: Achszahl multipliziert mit 10. Bei den richtigen schweren Brummern beträgt die Achslast meist sogar 12 t. Das sind die sogenannten geteilten Achsen bzw. Pendelachsen, zwei recht kleine Räder im Doppelpack jeweils auf der linken und der rechten Seite des Anhängers.

Which essentially translates to: For the calculation of the weight of the motor/lorry cab you multiply the number of axles by 9t. A four axle cab will be 36 tons (in reality usually 35t). For the trailer: No. of axles multiplied by 10. The really heavy units usually are 12t. Those are the split axles/ swaying axles, two sets of each two small wheels on each side of the trailer.

I know the article is by Germans for Germans in Germany. But we work with similar numbers and scales. According to this,a  40t lorry could survive on four axles which is plausible and applied when looking at most of what rolls along roads these days. Our lorries are shorter (and taller?) than this, but that shouldn't make a difference since they weigh the same and have an approximate 10t axle load.

Take from this what you like, but I really doubt that a 12t weight limit is insufficient for roads in the city. Rather, using the axle system present in the rails might have a positive effect. Increased realism and sensible limits would be the result.

[jamespetts]

If anyone can suggest better axle load values for any specific vehicles, please do let me know.

[rsdworker]

If anyone can suggest better axle load values for any specific vehicles, please do let me know.

my best suggestion is 20t for most vehicles

[jamespetts]

my best suggestion is 20t for most vehicles

I am afraid that this is a little vague: where does the number of 20t come from; does it apply equally to a Transit van as it does to an articulated lorry; does it apply equally to a minibus as to a double decker; does it apply equally to a steam lorry as to an early diesel variety? What of traction engines and horse carts? It seems highly improbable that all vehicles have the same axle load.

[Junna]

I am afraid that this is a little vague: where does the number of 20t come from; does it apply equally to a Transit van as it does to an articulated lorry; does it apply equally to a minibus as to a double decker; does it apply equally to a steam lorry as to an early diesel variety? What of traction engines and horse carts? It seems highly improbable that all vehicles have the same axle load.

Does it really matter that much? I mean, weight limits on roads are mostly total weight for convenience (but I have seen a bridge with a sign denoting axle load limit of 5 tonnes somewhere I forget). This 20t limit is surely just so that it is sufficient for the latter high-standard roads to carry vehicles of all weights...

[Spenk009]

I agree, it doesn't really make a difference. Unless we have a wind mill factory delivering to a wind farm at sea (which could make a very nice challenge on real maps), mobile homes being moved to camping sites or even generators being moved around to power stations (I'm thinking of one per month or so that makes having a lorry per link sensible but no need for rail access), we don't have to worry about axle weights.  And even if we do, such since the vehicles are designed for a standard of 10t or similar anyhow.

[Sarlock]

In BC, Canada, and many other places, standard maximum weights for axles for transport trucks are:

5,500kg for front drive axle
18,000kg for tandem axles at back of truck (9,000kg per axle)
18,000kg for tandem axles on trailer (9,000kg per axle)
24,000kg for tridem (3) axles on trailer (8,000kg per axle)



This weight restriction is not really for physical road load purposes but maximum load for braking, spring load on truck chasis, etc.

A road can basically handle any load thrown at it, though the wear on the road surface increases exponentially with axle weight, speed, braking action, etc.  Roads that have a lot of heavy truck traffic need to be resurfaced more often.