Tapering Lanes and Medians

When does one feature end and another begin? We found it to be especially tricky when dealing with tapering medians

Tapering Lanes

Let's take a look at how to determine where one lane begins, and where it ends:

In this example, we are working from the left to the right (as shown by the blue arrow). You can see that we go from two lanes to three, on the right side of the road (2nd image).

The exclusive right turn lane tapers into existence (yellow).  When entering lane information, the beginning of the new lane can be marked at the point where the lane comes to its full width.

On the above image, that point is marked with a red line, since the lane width stays consistent after that point.  As you can see, the beginning of the new lane is not marked where it first starts to taper into existence.

Instead, it is marked at the moment it comes into its full width. The segment between the red and green line will still contain ONLY FOUR LANES. Please use discretion when working on these instances.

Let's look at another example.

In the above image, we are still working in the 'right' direction.

Here, we have a lane on the 'left' side of the road that emerges similarly to the first example, but in the reverse direction.

In these instances, the point marked "A" is where the transition from three to two lanes occurs.

The segment between "A" and "B" will only contain the two non-tapering lanes in the lane editor.

Tapering Medians

Let's take a look at medians, which have similar, but slightly different rules.

Similarly, the divider tapers from a curbed median to a lane

In this instance, the end of the cubed median is marked where the lane comes to its full width.

This also marks the beginning of the lane. 

 Medians with Buffers

When dealing with curbed medians that taper into some sort of painted buffer, we generally choose the predominate feauture of that section. 

This differs from lanes splitting / identification because with lanes we always want the most accurate configuration and with buffers we can generalize.

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