Ada County Highway District

ACHD's Road Wizard Sunday, May 13, 2018 ACHD's Road Wizard

The reason why ACHD will not install stop signs at Tybalt Drive and Montague Way in Meridian's Tuscany subdivision; yield signs to be replaced by merge signs at the intersection of State Street/Idaho 44 and Idaho 55.

The Road Wizard Replies

Dear Road Wizard: The Tuscany subdivision in south Meridian recently had extra stop signs installed by ACHD at several intersections due to the subdivision being used by Eagle Road traffic while it was closed for bridge construction. Although the residents begged and pleaded, the stop signs were all removed once Eagle Road reopened. One "T" intersection in particular, at Tybalt Drive and Montague Way, has been the site of many near-misses and one dog death. It is a main access point for Siena Elementary. We were told by ACHD that unless the intersection had a high accident count, the stop signs aren't justified. Why does ACHD take such a hard line against what would be a very logical solution to hopefully preventing a tragedy? How can we get ACHD to change their minds?


Road Wizard:

ACHD traffic engineers are not likely to reverse the decision, so please allow me to provide some insight as to why.

Drivers are well known for disobeying stop signs (some call it "rolling" through) in low-speed locations within subdivisions. Adding more signs can increase that trend, which may lead motorists to ignore stop signs at more critical locations, such as at Bown Way and Riverwalk Drive in Southeast Boise. The Idaho Statesman recorded just under four minutes of video at the intersection and only one driver made a full stop in that time. And a half-dozen drivers didn't stop at all.

This is why traffic engineers apply specific analysis to the installation of stop signs. There haven't been any reported crashes at Tybalt and Montague since the subdivision was constructed about 10 years ago and the signs aren't necessary from a traffic control standpoint. Idaho Code already explains that at "T" intersections without stop signs or signals, drivers at the stem of the "T" are to stop for the through movement unless otherwise posted.

Dear Road Wizard: At the intersection of State Street/Idaho 44 and Idaho 55, there are yield signs for traffic turning west onto Idaho 44 from Idaho 55, and for traffic turning north onto Idaho 55 from Idaho 44. However, there are also long turn lanes for both of those directions. Drivers seem to ignore the yield signs, and use the long turn lanes as merging lanes. I have been stopped at the yield sign for west-turning traffic waiting for traffic to clear on Idaho 44, and have had drivers pass me on the right and proceed to merge. Why not replace the yield signs with merge signs?


Road Wizard:

Great question. Yield signs at "free" right turns like these tell drivers coming out of the turns that they are obligated to yield and even stop for conflicting traffic. The signs are usually posted where there isn't meaningful merging space.

But the Idaho 44 and Idaho 55 intersection has a good amount of merging distance. For that reason, posting yield signs for the right turns at this particular location isn't the best approach. The Idaho Transportation Department will replace the yield signs with yellow "merge with traffic" signs. They will also improve some pedestrian crossing signs.

Yielding to oncoming traffic is still part of the merging process, but the new signs will make it clearer that drivers don't have to yield right where the old yield signs were posted. They can continue traveling down the merge lane and merge into mainline traffic when appropriate.

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