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Nashville: I24 / Spring Street / Dickerson Pike

Post by JennRairy
Map Error is showing route goes through turn not allowed
https://www.waze.com/editor/?lon=-86.77 ... 98&env=usa

Why is there two ramps to connect the exit to Spring Street and Dickerson Pike. Looking at the road it appears both lanes allow access to Dickerson Pike. It appears overly complex. At minimum the left lane should be marked to allow the turn to Dickerson but it seems both lanes should be combined to be one exit ramp.

The ramps are locked to level 5 so I would like to assume there is a reason to not change it. If so how do we prevent further map errors?
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Post by Bigbear3764
Got a PM into WeeeZer14 on this. He will tell you why it is the way it is.
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Post by JennRairy
Thank you for the explanation, it helps.

My next question is: if both lanes allow access to Dickerson then why is the left one marked with a turn restriction? Shouldnt they both be marked to allow turns to Dickerson?
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Post by JennRairy
Question: What about moving the left lane ramp to connect to Spring Street only and not to the junction with Dickerson? Then it wont have its own turn option to Dickerson (the turn option for that lane will become the one from Spring to Dickerson)
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Post by paulwelch23
Here's the explanation:

The dual ramp is there to guide you to the correct left turn lane from the I-24 W off-ramp. The left left turn lane allows you to go west on Spring Street. The right left turn lane guides you to a lane that is a mandatory right turn that goes north on Dickerson Pike. WeeeZer14 has done this so that drivers who need to go west on Spring St. are guided to stay in the left left turn lane, so they are not forced to turn right on Dickerson Pike once they make the initial left turn.

From the outset it seems unnecessary, but by looking at the aerial views you can see that it is necessary for good guidance.

Does this answer your question?
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Paul M. Welch, PE

Tennessee-based CM, focusing on Middle / East TN and Memphis
https://www.waze.com/wiki/images/2/2a/W ... 00k_5c.png

Post by paulwelch23
Although your point is technically correct, the restricted right turn to Dickerson from the left left turn lane ensures that all drivers use the right left turn lane and are guaranteed to go to Dickerson. If the right turn is enabled from the left left turn lane, it introduces a risk that the driver may not see or hear the instruction in time to make the necessary right turn to Dickerson Pike. If someone is unfamiliar with the area and its lane restrictions, they could be given bad guidance and experience frustration.

Furthermore, if someone was in the left left turn lane I would bet that the GPS reception would not be accurate enough to realize that the user was in the "wrong" lane, and they still would get an instruction to make a right onto Dickerson. Have you experienced a problem going through this area?
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Paul M. Welch, PE

Tennessee-based CM, focusing on Middle / East TN and Memphis
https://www.waze.com/wiki/images/2/2a/W ... 00k_5c.png

Post by paulwelch23
Well, lemme refocus my last statement/question since I forgot that a map problem had been generated (Sorry!). You can wait for a reply from WeeeZer14, but I would just close the problem and mark it as solved. This is sort of a grey area at this intersection since the inside lane turning radius can be so much smaller than the outside lane turning radius, and the map problem has been generated. A possible (but not great) solution would be to make the outside turning lane radius smaller, therefore allowing the client to think that the user is in the "correct" lane.
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Paul M. Welch, PE

Tennessee-based CM, focusing on Middle / East TN and Memphis
https://www.waze.com/wiki/images/2/2a/W ... 00k_5c.png