Can we put a yield sign to warn drivers to yield when turning left at a sharp intersection?

No, it is not allowed to mix stop and yield signs in a single intersection with exceptions for large multi-lane intersection and channelized turn lanes.

Diagram of intersection with existing and proposed signs - use this configuration

Diagram of intersection with existing and proposed signs - use this configuration

Text from MUTCD:

Section 2B.04: Right-of-Way at Intersections

Standard
Except as provided in Section 2B.09, STOP signs and YIELD signs shall not be installed on different approaches to the same unsignalized intersection if those approaches conflict with or oppose each other.

Resources

MUTCD Resources

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This work by the Cornell Local Roads Program (CLRP) is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.