Here’s my column from the Sunday paper. If you’ve already read it elsewhere, please skip on down to the comments below. Thanks.

Alert reader Jan from Brooklyn Center does a bit of fuming whenever her car waits at certain intersections:

Reading your articles and others on possible ways to save on gasoline, I have seen no comments on one of the traffic signal restrictions that is applied arbitrarily all over the city — that is the “left turn on green arrow only.”

While there are many places where this is a necessity because of heavy traffic and dangerous intersections, there also are many intersections where traffic is light and you can sit idling when there is no traffic from any direction.

Alert readers Gregg from Eden Prairie and Yvonne from Brooklyn Park wrote in to express similar unhappiness; Gregg even called for a law against red left-turn arrows.

While the arrows may seem arbitrary, they’re not, says Kevin Schwartz, an engineer for the Minnesota Department of Transportation’s metro district. Sight lines, speed limits, traffic volumes, the number of oncoming lanes and the number of turn lanes all play a role in determining which intersections get left-turn arrows.

The red/green arrow setup is vastly safer than what traffic folks call the “green ball” — a plain round green light — because the arrow removes the judgment call of when to zip across oncoming traffic, Schwartz says.

Schwartz said intersection designers tend to err on the side of safety, and while the arrows may be appropriate during rush hours, he knows they can be frustrating when traffic is light.

A remedy may be on the way, he said, in the form of a new kind of light: the flashing yellow arrow, which can be used during off-peak periods and allows left-turning drivers to proceed with caution.

Some states already have them, and one is being tested at Hwy. 110 and Dodd Road in Mendota Heights, Schwartz said. He’s hopeful that they’ll eventually be approved for wider use; Jan, Gregg and Yvonne are hoping so, too.

SCOOTING ALONG
Alert reader Gerry from Bloomington writes:

I’ve encountered many motor scooters on the local streets. These seem to be able to only go about 30 mph. Many times they were on roads with speed limits of 35 and 40 mph. Have they a right to be there even though they cannot go the speed limit?

Bloomington is very prepared to answer Gerry’s question: The city has put together an 11-page guide on what sorts of vehicles can go where. Mopeds and motorized bikes that can travel up to 30 mph aren’t allowed on freeways but are legal on city streets, even those with higher speed limits.

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