Right-turn spurs get the axe in Alexandria: is it safer at any speed?

The vehicularly inclined among us have probably noticed how, in recent years, various cities have adopted new stripes, bollards, stanchions, and sometimes modified curbs that make it highly inconvenient to make right turns.  Yes, this is deliberate. No, it’s not happening to give motorists a hard time, though it definitely doesn’t make things easier, which is deliberate as well. Here’s an example in a newer part of town in Alexandria, Virginia.

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The busier collector road, King Street, connects Old Town Alexandria (about 1.5 miles to the southeast) to the more westerly DC suburbs like Falls Church and Tysons; it is, after all, Virginia State Route 7.  The connecting street, local Scroggins Road, gets only a fraction of the traffic, since it serves a single-family residential neighborhood, but since it provides a link between King Street and busy collector Braddock Road to the north, it probably receives considerably more free-flowing vehicles than the usual road of a mere quarter mile in length.

In the above photo, I’m standing at a spur that facilitates right turns from northbound King Street onto Scroggins Road.  But the photo is deceptive: in reality, a series of stanchions prevent access to that right-turn spur. Here’s a view from just a few steps backward.IMG_1420blocked right-turn spur in Alexandria at Scroggins RoadSo why do this?  It’s not really complicated: the design of the spur came from an era when the primary value of traffic engineers and public works departments was to convey vehicles as efficiently as possible, and efficiency usually correlated almost exclusively to high speeds.  After all, the biggest factor influencing a Level of Service (LOS) is minimization or absence of delays. This right-turn spur configured a three-way intersection so that the turn radius was as generous as possible, precluding the need for drivers to slow down much–if at all–as they negotiated their way from King Street to Scroggins Road.  I don’t have the measurements for this right-turn spur, but if it’s greater than 35 feet, it will generally achieve maximum efficacy for facilitating high-speed right-hand turns. Here’s an overhead view of the site, with the key intersection circled in purple:Screen Shot 2019-12-26 at 11.13.32As if obvious from the map, it was never a T-shaped intersection; really more of a Y.  The right-turn from King to Scroggins is already approximately a 145-degree angle; the right-turn spur emphasized this generous turn, allowing vehicles traveling on average 35-40 miles per hour along King to minimize the need to decelerate as they veered onto Scroggins.  It’s possible they could maintain these speeds.

The result is nice for cars but terrible for the exclusively residential character of the neighborhood for which Scroggins serves as a backbone.  Here’s a view along Scroggins:IMG_1423And here’s looking back in the other direction, gradually approaching the intersection with King Street (State Route 7):IMG_1416IMG_1417The only vehicles that will find utility to the spur are those that need the driveway that intersects it, indicated by the SUV in the left of the second photo.  And those vehicles can only access the driveway from the Scroggins Road approach.

This new transformation is onerous for motorists.  It forces them to enter the intersection at something much closer to a 90-degree angle, clearly visible in the right half of the photo below:IMG_1415Through this new design, cars must slow to a near stop before turning right onto Scroggins–a safer condition overall.  The environment only stands to benefit from these mild interventions, which certainly make Scroggins Road less attractive as a cut-through street–a condition for which it is not suited and residents never expected it to become.

But it’s not just about the residential character.  Although this part of Alexandria does not get a great deal of pedestrian traffic, it certainly can accommodate them: sidewalks are usually present on at least one side of the major streets, and radar monitors the speed of motorists to prevent egregious moving violations.  These stanchions and stripes at King/Scroggins are part of a broader effort to improve pedestrian safety.IMG_1418The lightly landscaped median creates a pedestrian island–a refuge allowing walkers to make it halfway across the breadth of King Street, then to wait safely for clearance coming from the other direction.  And then, once they’ve fully crossed King Street, pedestrians enjoy near-complete safety on the now restricted right-turn spur onto Scroggins.

These two Google Street View archived images show the full array of transformations that have taken place these last few years.  Here’s one from the fall of 2012, showing what King/Scroggins looked like with the right-turn spur fully operative.  Four years later, all the improvements are in place.  As a general rule, I would typically extol these efforts: they not only radically alter the character of Scroggins Road–reinforcing its purpose as an exclusively local street intended to serve homeowners and visitors to the neighborhood–but they reduce the likelihood of vehicle-pedestrian collisions, which, given the speeds of most cars traveling along King Street, could prove fatal.  Using mostly striping, lightweight reflective stanchions, and a few new curbs, Alexandria improved an intersection at a far lower cost than re-engineering the intersection altogether by ripping out pavement–much more akin to the felicious results in Bethlehem, PA than the less successful attempt in Baltimore

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No, I don’t think the intersection of King and Scroggins will become a hub of pedestrianism any time soon.  But, just a quarter mile further along King Street is the entrance to a community center, and just beyond that, the main location (Grades 10 through 12) of Alexandria’s only high school.  In other words, the area affords numerous opportunities for pedestrians, and any effort to reduce risk deserves accolades. All the better if the Alexandria Public Works Department (or Virginia DOT) can achieve it with a little paint and some poles.  And while motorists might perceive this as an affront, given the history of designing right turns to accommodate them, at least we have one clear point where the conditions aren’t hostile to pedestrians. And when cars and peds come into contact, we all know who’s going to win.

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12 thoughts on “Right-turn spurs get the axe in Alexandria: is it safer at any speed?

  1. Alex Pline

    Also know as “slip turns” they are a scourge any place that has people outside vehicles (ie has/requires a crosswalk). Like oil and vinegar. Glad to see Alexandria eschewing the autocentric dogma of the last 50 years.

    Reply
    1. AmericanDirt

      Thanks for that reminder, Alex; I knew there was another name for them. One of the most enduring legacies from 1970s-era planning that perceived the car as the alpha and omega for private transportation, and designed our streets accordingly. It’s consistently easy to tell all across the country when cities reached that time period in the development: usually suffering for sidewalks, unusually large lots, and roads that accommodate nothing other than cars (sometimes lacking even stormwater conveyance). It’s hard to imagine how many more decades and billions of dollars it would take to remove these scars on urban landscapes.

      Reply
  2. Chris B

    But it’s an upscale suburb…they could have built a roundabout! All the cool kids are doing that! Even if it does lengthen and complicate pedestrian passage…

    Reply
    1. AmericanDirt

      Out here in NoVA, trendy though it may be, roundabouts don’t seem to have caught on in the least. I see them in Maryland from time to time. It’s possible that Virginia has not yet introduced the enabling legislation necessary; when I type “roundabout state enabling legislation”, the first state listed is Indiana…as well as the second and fifth. Funny how that works.

      Reply
      1. Chris B

        Gosh, the transportation planners in NoVA must not read CityLab’s fawning coverage of Carmel’s >100 roundabouts. 🙂

        (Have you seen Greenwood’s fix for the abomination that was the confluence of Smith Valley/Madison/31? Good solution but people mess it up trying to make prohibited left turns at 31.)

        Reply
        1. AmericanDirt

          I haven’t seen the one in Greenwood you’re talking about–haven’t made it to that part of Greenwood in quite some time. But I know the intersection, and it begs the question (at least for me), can three intersections get easily absorbed into a roundabout from both an engineering and a layperson’s usability perspective?

          I had the idea of reintroducing the centrality of Meridian Street in Babe-Denny while stopping the annoying double-naming of Madison Avenue by trying a roundabout (or some other three-way intersection) at Henry Avenue…which would made Madison Avenue, in its current manifestation, flanked by roundabouts.

          Here was the old article, which didn’t get a lot of mileage, perhaps because it was mostly me playing SimCity. Still a fantasy though.
          https://dirtamericana.com/2012/07/madison-gateway-navigational-confusion/

          Reply
      2. Alex Pline

        Roundabouts are a mixed bag, generally bad for cycling and meh for walking, but they do move cars efficiently. However, they are VERY spendy. Keeping street lanes to 1 in each direction with 9′ or less width and having separated bike/ped infrastructure is a much better choice. Keep wide multiple lanes for limited access roads if you want to convey cars.

        Reply
        1. AmericanDirt

          Up in a less developed part of Prince George’s County, MD, I recently worked with a customer whose initial impulse was to solve a growing traffic problem with a roundabout. However, we revealed that the entire reason for adding the roundabout–to mitigate traffic coming out of a massive new employment node onto a rural collector–wouldn’t help, because so much of the traffic flow approaching the intersection would come from one direction at a single time (4-6pm). Roundabouts work better when there’s a relatively even flow from all approaches to an intersections. In this case, it was far better to use a signalized intersection that remained green and vehicle-activated 90% of the day, only reverting to a conventional stop light during peak periods. And…as you noted…it was cheaper.

          Reply
  3. Ralph L

    I wonder how many cars are rear-ended when they slow to make the turn.

    Thirty years ago, the only pedestrians for half a mile were the high school sheep wandering westward for a smoke and a burger.

    The City used to deliberately impede N-S traffic to force eastern Fairfax commuters onto Shirley Highway and Route 1. Likewise, they made the giant, complex intersection of Braddock, King, and Quaker Lane just to the west as bad as possible so people would avoid it–by using Scroggins.

    Reply
    1. AmericanDirt

      Interesting. You’re absolutely right that the nearby three-way intersection is terrible, especially for NB cars on Quaker trying to make a left turn on to King Street, which almost certainly means they’ll be left idling in some neverland that blocks traffic passing through on Braddock. It doesn’t surprise me that Scroggins became a cut-through, which is probably highly unpleasant for the people living on it, who rightfully expected their street to be a quiet, local-only road.

      As for the turn radius from King onto Scroggins, I’d say it’s still worth it for setting the standard for driving along Scroggins: it should not be a high-speed road under any circumstance, even if the risk of hitting pedestrians is infinitesimal. If someone rear-ends a motorist slowing to make that hard right turn, obviously the fault is the same as it always is under such conditions. Yes, the current configuration doesn’t allow any real turn lane, forcing cars to back up behind a car slowing down to turn right; this configuration is typical of right turns on rural roads (of which this most certainly is not). But the previous “slip turn” condition was so generous that it was almost a straight line for cars on King Street (about a 160-degree angle), and even now, it’s still hardly a right angle; probably closer to 115 degrees. The addition of these barriers is likely to inconvenience a motorist to the tune of about 5 seconds maximum.

      Reply
  4. Ralph L

    I’d forgotten that I was rear-ended because of a traffic holdup in front of my then house on the narrow part of King Street just to the east, but my subconscious must have remembered.

    I notice they’ve turned the outside lane into a bike lane. That should make the turn easier. That stretch was probably the least used mile of the entire length of Route 7, so 4 lanes weren’t really needed.

    Reply

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