# Moving load Optimization vs Traffic lane optimization

**Question**:

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Hi,

I''m working on modeling a curved steel composite structure to CSA-S6-14. I am in the process of defining the lanes for moving loads. Due to the driving platform width of 10.5 m, I will have to consider both two lanes and 3 lanes. Currently, I am trying to model the 2 lane scenario, where the 3.0 m wide trucks will need to be placed in a 5.25m wide lane, and the lateral position of the truck varying to determine the maximum load effects on adjacent girders.

I believe I should be using the moving load optimization feature to do this, as I have started to set up in my model (see attached). I''ve tried to set this up by using the "number" input, by copying the element numbers from my girder group and pasting into the number box. However, when doing so, some of my elements seem to be defining the lane line in the opposite direction of all the other lane lines. I''ve tried instead defining it using the other methods (two-point/element) but the same issue is presented.

Can you please advise as to why this could be happening and how I can fix this? I am assuming that, even though I have selected "both" for the direction, this line direction will still model the loading incorrectly.

It also appears that the boundaries of the lane width are not shown on both sides of the lane line (the green dots) - I''m not sure if the absence of these dots is just a graphical issue or a issue with the definition of the lane. Your comment on this would also be appreciated.

Thanks for your time,

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Hello User,

Thanks for writing to us.

We need to have ascending order sequence of element numbers for the selected line lane. This can be achieved by renumbering the element numbers using ' Renumber Element ID' option.

I have renumbered the girder 2, element numbers and applied the traffic lane correctly. PFA the revised model.

kindly reply back if you have any further issues.

Regards,

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Title : Lane Load Optimization - incorrect lane line direction

Thanks for the help.

I was wondering whether you could explain or provide a resource explaining how the lane line optimization works and the difference in the options available for defining lanes.

Specifically, what does the moving load optimization lane definition do vs the lane optimization option in the standard lane definition?

Your comments are much appreciated, thanks!

Regards,

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Hello User,

Moving Load Optimization and Traffic Lane Optimization are two different things. It depends on how you use this features for moving load analysis as both have different procedures to apply moving load as per code.

1)

__Moving Load Optimization__

Moving load optimization allows you to find the number of loaded lanes and the exact position of vehicles in the transverse direction as well as longitudinal direction, which will give the most critical responses. So it will float the vehcile throughtout the optimization lane (carriage-way).

2)

__Traffic lane optimization__

When the “Traffic Lane Optimization” option is checked on, Midas Civil transversely floats the vehicle load within the lane and obtains the worst effect of the vehicle placement for each element. And this is done for one single lane.

Kindly refer the help manual for details http://manual.midasuser.com/EN_Common/Civil/865/Start/05_Load/07_Moving_Load_Analysis_Data/Traffic_Line_Lanes.htm

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