Defining traffic lanes for skewed RC slab bridges

Question:

We are currently designing a RC slab bridge with skewed angle of 20 degrees. I defined the traffic lanes by different ways as shown below. As seen in the image below, the 1st figure used the nearest longitudinal elements for eccentricity, while the right figure used the bottom longitudinal elements for eccentricity. Which one is correct?? 

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Answer: 
Among the two figures, the left figure looks more reasonable. However, in order to consider the lane correctly in the skewed bridge, you need to consider the skew angle as shown below.