Blue stripes on roads aren’t common. So what do they mean?!

In the landscape of the American roadway, four colors seem to reign supreme for background signage: green, yellow, orange, and blue.  Green (with white lettering) is the status quo across freeways and most municipal markers for value-neutral guidance and wayfinding.  Yellow (with black lettering) is most pervasive in signaling a permanent aberration: e.g., a change in the elevation of a road, its bearing, or lane merges, all of which intend to break a driver from a numbed complacency, especially if he or she is unfamiliar with the roadway.  Whether a local or a visitor, yellow communicates to drive cautiously and slowly, because the road conditions ahead are not ideal.  Meanwhile, orange backgrounds (again with black lettering) represent a temporary aberration intended to alert locals and visitors equally: they signify an unexpected place for construction, a detour, or any radical change in traffic patterns.  The critical difference is that the condition is short-term.  Less common (but hardly rare) is blue (with white lettering), which has almost morphed into “none of the above” for informational signage, often indicating attractions or private businesses of particular interest to a visitor; I covered this blue semantic fuzziness last year, since these attractions can be permanent (historic landmarks) or unpredictably short-lived (a restaurant).  The focus of this article is indeed the semiotics of the roadway, but it’s time to pan the gaze downward to the road itself, where stripe colors are more streamlined: white demarcates a general message of permission (what is allowed), yellow conveys a message of limitation (what is restricted), and most other colors are rare.  It’s those rarities that interest me…which pivots the camera lens back to blue—specifically, to blue stripes on the pavement.

Road stripes have a dedicated place in car culture, but the palette is narrower.  The overwhelming majority are white or yellow.  On the American roadway, white typically divides the paving surface into subunits, but two adjacent subunits have the same function: lanes in a multi-lane arterial, each guiding traffic flowing the same direction.  A one-way street will exclusively feature dashed white stripes in the roadway.  They’re the most common color for conventional parking bays as well, while stripes perpendicular to a road’s direction of travel usually demarcate the place where a car should idle or stop (often at a pedestrian crosswalk, which typically but not always means more white stripes).  Meanwhile, yellow stripes reflect subunits with differing functions, thereby implying a stricter standard or restriction in crossing the stripe.  Any American roadway with yellow stripes indicates two directions of travel.  Yellow is the typical color implying some restrictions for parking, either on a curb or sometimes on lots.

So what about those blue stripes?  Most American motorists may have to ponder a bit to come up with a single answer.  However, those with handicapped parking permits know exactly where blue stripes come into play; handicapped parking spaces (or the handicapped symbol itself) often feature some distinguishing blue, which is by far the most common deployment of the color on concrete or asphalt.  Other uses are so rare that they even left me scratching my head.  Like this one:

The first conclusion one might draw is: “It’s obvious why Public Works Departments don’t use blue more often.  It doesn’t stand out as well as yellow or white.”  It’s hard to deny this strange road indicator is striking less for its color than for the unusual, almost erratic curvy pattern: like a sine wave executed poorly.  The shape and character is so atypical for a roadway that it is far more of the attention-getter than the blue stripe itself.

There’s got to be a story behind it, right?  The blue stripes in question here come from the trendy Remington neighborhood in Baltimore, and I’ll confess that the above photograph isn’t entirely honest: I cropped it to highlight the mystery.  Here’s a more complete depiction:

The mulch and cracks in the sidewalk obscure the lettering somewhat, but it says “SUMWALT RUN”, flanked by curvy parallel lines—an almost universal symbol of water.  The fact that the blue stripe climbs the curb onto the sidewalk indicates that it is more than just a marker for motorists.  

The statement on this blue stripe—“LOST RIVERS FLOW BELOW THESE STREETS”—isn’t cryptic to the average urban historian, but how many of those are really out there?  For the uninitiated, it just sounds like poetry.  I certainly won’t claim to be an urban historian, and while my suspicions proved well-founded, it took a little digging to corroborate beyond the clues.  In the Mid-Atlantic, the word “Run” preceded by a proper name is a fairly common term for a tributary to a larger creek or river.  Northern Virginia is filled with them: Hooffs Run, Four Mile Run, Holmes Run, and so forth.  A century ago, “Sumwalt Run” was a stream that meandered throughout what at the time were the outskirts of Baltimore.  Its source was Charles Village, a neighborhood adjacent to Remington that, like Remington, enjoys a heavy association with Johns Hopkins University to the immediate north.  Sumwalt Run flowed to Jones Falls, another creek who at its mouth serves the easternmost slip in Baltimore’s famed Inner Harbor.  While Jones Falls largely survives as path that parallels Interstate 83 in Baltimore (nicknamed “Jones Falls Expressway”), Sumwalt Run was less fortunate.

A recent article from Hopkins covers its history: as the Olmsted Brothers responded to a 1902 commission to improve the park system, unchecked development nearby already had channelized portions of Sumwalt Run to underground culverts, making room for what was the brand-new community of Charles City.  This initiative thwarted the brothers’ plan to integrate Sumwalt Run into Wyman Park (which eventually formed the western border of the Hopkins campus.  So, from 1907 to 1914, the Olmsteds buried the rest of its meandering three-mile course, enabling further development of the Remington neighborhood.  With portions of Sumwalt Run flowing up to forty feet below street level, it is but an anecdote in the geography of the city, at least until 2020.

And thus, the blue stripes in Baltimore have revealed their function: they are histrorical and artistic, but not a tool for traffic management.  The City commissioned local artist Bruce Willen to create a permanent linear tribute to Sumwalt Run called Ghost Rivers.  The blue stripes iterate across a 1.5-mile path tracing much of the length of this now underground stream, offering markers and wayfinding signage to explain what happened.  Willen chose the same shade of blue that “references the hue of waterways found on vintage maps”; it also helps avoid confusion with other blues or pavement markings.  It is distinct without being alarmist.  Furthermore, the gentle sinuousness and imperfect linearity—it traces the “ghost river”, which does not flow in a straight line—immediately suggests to the untrained eye that this is not a cautionary symbol.  Perhaps most importantly, it raises a question about prior urban engineering initiatives—was burying Sumwalt Run and other Baltimore streams the right decision?—without steering the onlooker to a clear answer.  It’s there to inform and to nudge more questions, but not to editorialize.

In most respects, I’ll assert that it’s a more effective deployment of blue stripes than this next example a hundred miles away.

Does it even show up?  The more conventional striping is plain to see: a double yellow line indicates a two-way street where, thanks to the lack of dashes in the stripes, passing is not allowed.  In between the two yellow lines is a stripe of deep blue—evidence, once again, why blue stripes are not pervasive or desirable at commanding a motorist’s attention.  My guess is most people wouldn’t notice it, but it’s a permanent fixture here on Main Street in Luray, Virginia, even at a white crosswalk.

My initial, dead wrong assumption was that it represented some scenic path through the Blue Ridge Mountains.  Come on: this is Luray, Virginia, the heart of the Shenandoah Valley.  And while Shenandoah Valley National Park is indeed a part of the Blue Ridge Mountains, which stretch northward into Pennsylvania and south to the Great Smoky Mountains of North Carolina and Tennessee, the Blue Ridge Parkway in Shenandoah Valley links with Skyline Drive, which runs about ten miles east of Luray.

The blue stripes on Main Street Luray are, most likely (I cannot confirm), representative of the “Thin Blue Line” between order and chaos; a symbol most common in flags, but deployed strategically (and often subtly) as a gesture of respect to law enforcement officers.  The blue stripes on a road like Luray are not compliant with Manual on Uniform Traffic Control Devices (MUTCD), which stipulates that no markings should exist between double stripes; the pavement must be visible to offer uniform contrast.  That said, dark blue stripes have become canon in some parts of the country, not just honorary but as a wayfinding tool leading to the closest police station.  Attempts to harness FHWA rules to eliminate them have elicited strong resistance, and, viewed in the context of other politically charged pavement markings, these blue stripes elicit little confusion or consternation among motorists.  Most people, I suspect, don’t notice them; I’d imagine I’ve seen them many times prior to Luray and they didn’t even register.

Blue is a soft, cool color, perhaps the ideal hue for signifying something interesting but non-essential.  Its comparative non-assertiveness may explain why it’s such an effective catch-all for road signs.  Lost rivers, law enforcement, and Lenny’s Sub Shop.