On Mildred Lane and Elsewhere our Minor Arterial Standard is often too Big

Over at our Strong Towns group, Planning Commissioner Slater takes issue with a priority on more narrow lanes for safety.

Mildred Lane at the park is wide and zoomy

He cites Mildred Lane as an example, but does not show Mildred Lane and instead shows a typical Salem cross-section in our standards.

But the discussion, as informed as it is, does not attend enough to the particularities of our standards as they are actually built. As I read the note, it builds to a support of that current cross-section and of our current approach.

via FB

Instead, from here it has seemed clear this cross-section, even with 11-foot travel lanes, is often still too wide and still induces speeding in many places around town.

More particularly, how is it possible to argue that the cross section on Mildred Lane at the park (top image) is safe and does not induce speeding? If you start with a 35mph limit and add the wide and open street, it's clear why speeding is common there.

Between the park and the walled off subdivision, there are no turns possible! Only straight line travel is possible.

There is no reason to have a continuous turn pocket.

There is so much slop in that cross section that even striping for 11 foot travel lanes is clearly excessive. With a better cross section, maybe an 11 foot width is defensible. But not in this one.

On the specific question of lane width, Strong Towns said recently

[M]ost often, our policies treat an 11- or 12-foot lane as the default, and allow the engineer to make a case for a narrower lane width.

This is backwards. A 10-foot lane, at the widest, should be the “default setting” for any sort of urban street: a place lined with homes and businesses, where traffic should flow slower than 35 mph. This should be understood as the risk-averse approach. If the engineer wants to make the lanes wider, they should have to justify the choice.

This is still a controversial change. It shouldn’t be: all the evidence points to the safety benefits of narrow lanes and traffic calming. But conventional U.S. engineering “wisdom” has said the exact opposite, for decades.

That fact ought to be a huge scandal.

Jeff Speck agrees, centering a ten foot standard in Walkable City Rules.

Two rules on 10 foot lanes
Jeff Speck, Walkable City Rules

You'll note that Mildred Lane is signed for 35mph — at a park with kids! The street is also signed wrong in addition to being designed wrong. It's wrong all the way around.

A Current Example

At Fairview Hills, which the Planning Commission is analyzing right now, Battle Creek Road is proposed to be widened to basically the same cross section.

Conveniently, because the Hearing at the Planning Commission was continued, the Second Supplemental Staff Report has information on a speed study. It was not included in the formal Traffic Impact Analysis or in the first two Staff Reports. The street is posted for 40mph limit, and half of drivers exceed that. 15% of drivers go 48mph or more!

15% of drivers go 48mph or more!

The City proposes to approve widening on a street
already known for speeding

In that Second Staff Report, the City also says "the issue of speeding...is not something the City can address [right now]." 

But by approving widening, they are inducing more speeding! They propose to make the problem worse. They said, "it would be better to wait until the site is fully built out, and which time an investigation [could be made]." This has it all backwards. We should be building roads for the speed we want. Not building for an excessively high design speed, inducing that speed, and then hoping to sign it for a slower speed and asking for compliance with a sign disconnected from and in tension with the design speed. This is plainly at odds with any "Twenty is Plenty" and Vision Zero planning.

For a road leading to Leslie Middle School, the current legal speed is already much too high!

Lane width is one of many tactics for reducing design speed. The broader issue on Mildred Lane and on Battle Creek Road is that the City standards for a minor arterial embrace a design speed much too high for passing through residential neighborhoods where kids should be expected.

On Mildred Lane and its crashes see:

• "Catastrophe on Mildred Lane Shows Problem with Road Design" (2021)
  
• "City Response on Mildred Lane focuses on Signal, not enough on Speed" (2022)
  
• "Remedy on Mildred Lane Misses Real Cause of Problem" (2023)

A "Built out" Example

Just up the road, the extension of Battle Creek at the school, on Pringle Road a recent pedestrian refuge island shows signs of crashes and speeding. (Doesn't the vista too look like it would induce speeding?)

Tree in refuge island at Copper Glen Drive (2021)

Two years after completion the curbing was dinged from impacts and the tree missing.

Tree all gone! (Nov 2023 via google)

On 17th Street and Chemeketa at least some flexposts have been broken off, and the curbing is also dinged up.

If the flexposts aren't safe, how are people safe?

The "standards" are not working here!

And in fact the City just got funding for another enhanced crosswalk on Pringle Road just a block away from the one with the missing tree.

The need to improve crosswalks shows speed problem

If our Minor Arterial cross-section was safe, and if we designed the road for appropriate school and park speeds, we wouldn't have to be backfilling with so many of these enhanced crosswalks with beacons and refuge islands at the school. Because we widened the street and induced more speeding, we have to add mitigations. 

Maybe we should just design for the speed we want from the start? Instead, we get hung up, over and over, on capacity and flow.

Former Councilor Stapleton is right. Speed, not capacity, needs to be the center of analysis.

Former Councilor Stapleton on speed