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# Minimum curve radius along the road

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## Minimum curve radius along the road

(OP)
Hello,

I'm trying to set up a spreadsheet to calculate the cargo securing or lashing needed to secure a load to trailers in order to make the transportation safe for a lot amount of kilometers.

A force I need to calculation is the centripetal force acting on the convoy while doing a curve, and one of the input is the radius of the curve.

The thing is I'm doubtful over is there is a minimum radius often considered for road design, in order to avoid to go through a route survey of the specific road to take study each one of the curves.

Thanks in advanced, and have a nice week.
Replies continue below

### RE: Minimum curve radius along the road

1367 Peel Regional Rd 11
https://maps.app.goo.gl/8xgBhX6NsjigRjK17

Trucks not allowed (and signs indicate such)

The terrain, and property lines, dictate this.

Motorways are built to standards that don't apply to smaller roads, but you can't complete your entire journey on motorways ... sooner or later you will have to get out.

### RE: Minimum curve radius along the road

You are going to find that there are bounds to the lateral acceleration that the vehicle is capable of doing, and lower limits that passengers consider comfortable in normal driving, but don't disregard emergency stops or lane changes.

### RE: Minimum curve radius along the road

(OP)
Hello,

But what are the standards? There should be some minimum standards to be followed...

### RE: Minimum curve radius along the road

They will vary depending on type of road. And, you are asking the wrong questions for what you said you are trying to do. Cargo has to be secured to the limits of what the vehicle can do regardless of the shape of the road. It has to remain secure if the vehicle has to do a panic stop. It has to remain secure if the driver has to do an emergency lane change. It has to remain secure when travelling over bumps and dips and rough pavement.

How much practical real world experience do you have with lashing loads down?

Trying to secure a heavy expensive load down with the skinniest possible bungee cord that you can get away with, is a fool's errand.

Tell us what you are really trying to do, and why. Do you work for a shipping company trying to save money on ratchet straps? Do you work for a trailer manufacturer and you're trying to design in load attachment points on a trailer? Or what's the situation?

### RE: Minimum curve radius along the road

The maneuver that puts the highest lateral g into the vehicle is the moose test. https://en.wikipedia.org/wiki/Moose_test Typically corners in Australia have posted recommended speeds that lead to lateral accelerations less than 0.3g, and more likely 0.2 (subjectively). The actual procedure is https://www.dit.sa.gov.au/?a=657926 Actual data suggests that 100 kph at 200m radius, 0.4g, is typical in practice (I don't have figures for trucks). This report attempts to summarise https://www.ccmta.ca/web/default/files/PDF/Report-...

I would emphasise that the higher lateral accelerations result from maneuvers, not curve following, and that timing the steering motion can generate very high loads on the cargo. If the load shifts during this then you will have a very cross truck driver coming for you https://youtu.be/-ROCBQ35FR8

Cheers

Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

### RE: Minimum curve radius along the road

There are too many possible combinations of speed, radius, banking, profile, pavement friction values, etc. for that to bee a useful approach.

For a tractor trailer, rollover thresholds are much lower than cars. The worst cases are top-heavy loads and partly loaded tankers with sloshing liquid. The threshold can be from 0.25g to 0.5g.

First, check the regulations on securing loads where you are. In the US, I think that would be the FMCSA. Take the higher value of the applicable regs and the rollover threshold plus an appropriate factor of safety. Remember that low cg trucks like lowboy trailers will have higher thresholds.

My glass has a v/c ratio of 0.5

Maybe the tyranny of Murphy is the penalty for hubris. - http://xkcd.com/319/

### RE: Minimum curve radius along the road

There are standards for this sort of thing - for instance EN 12195 in the EU.

Bear in mind that there's more than one way of securing a load. Direct lashing (eg crossed chains fore and aft) is popular for attaching vehicles to the back of trucks, but for loads that don't have good tiedown points, the aim is either to pull the load down onto the bed then try to show that you've created enough friction to stop it moving - or to constrain it within the head and side boards of the bed, then try to prove it won't roll over the top.

A.

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