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Michael Hannigan
Michael Hannigan, Consultant
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Experience:  25+ Years in the field
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How much volume of 40 ton trucks per minute is safe to use

Customer Question

How much volume of 40 ton trucks per minute is safe to use a 12 meter wide road for hauling. Unpaved surface.
Submitted: 2 years ago.
Category: Engineering
Expert:  Michael Hannigan replied 2 years ago.
Hello. My name is***** can help you with your question. A 40 ton is between 245 inches and 265 inches and it's different from one truck to another because it's determined by the wheelbase which is wider than the haul. So 6.3 m to 6.7 m. So, the trucks cannot pass each other coming in different directions or even in the same direction for that matter. Now, if it's one way traffic then it's really going to come down to how the road drives what the grade is how flat the road is and if all of those things are ideal then they will only be limited to how fast you could go. At 55mph you clould see one of those trucks pass within 2 seconds, so 30 per minute minute, meaning if they are already moving and they are packed in pretty close three seconds each to pass a certain point would give you 30 a minute. But because of stopping distances at 40 tons I would imagine you'd want to build in some space between them. It would take a 40 ton t driving 55 mph approximately six seconds to stop on pavement - double that on unpaved... 12 seconds. Adding 12 and 2, I'd round up to 15 seconds per truck safely - 4 per minute. But no traffic coming the other way.
Customer: replied 2 years ago. latest info is the trucks are only 3.10 meters or a little more than 10ft. The road is 12 meters with 2 lanes per direction.

Expert:  Michael Hannigan replied 2 years ago.
Actually, the width number that I looked up is incorrect - I had already doubled the numbers and then put them down as the width of a single vehicle. And yours is closer to reality. To be legal on the street and US it would have to be a little bit smaller but since these are unpaved roads I'm assuming you know the size of the vehicles because they are obviously vehicles much wider. In this case you would have enough room for both lanes in each direction – one for travel and one for passing. At least, that's the way I would figure it because this would eliminate any guesswork with delays for breakdowns and or accidents. And I don't believe you could have four lanes of 40 ton trucks safely traveling that closely to each other, but it would be quite safe to calculate based on one lane in each direction, the second lane provides a buffer for both maintaining distance between trucks and for unscheduled downtime which would otherwise bring everything to a stop.
So I would say this is a much safer scenario with these numbers and much more foolproof – and it would get you, I would estimate, eight per minute. Of course there are many many variables in here and I've given you my reasoning for the numbers that I gave you. But they could certainly be adjusted and still be reasonable either way.

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