Wednesday, March 27, 2013

Dissolving Border Vacuums, Part 4

Last time we discussed solutions for sunken railroad and highway corridors, so this time let's look at their elevated corridors. Over the coming months we'll look at solutions for many other kinds of border vacuums and see if they could apply to Baltimore.

When there's no farmers' market, the JFX isn't a place you'd want to linger.
As with their sunken corridors, elevated railroad and highway corridors often form desolate border vacuums. But as Steven Dale argues, this doesn't mean they're inherently inhospitable: “Any long and narrow border is easily fought by increasing connectivity of uses across the two sides via careful and intentional design interventions that overwhelm the border. So while people lament things like elevated expressways and viaducts, that’s due more to a lack of imagination and creativity than any objective understanding of the problem. We need to stop making them out to be the monsters they aren’t.”

As with the sunken corridors discussed in the previous post, most US cities never really bothered to integrate their elevated railroad and highway corridors into the urban fabric. But it only takes a little creativity to transform even the most unpleasant elevated corridors into unobtrusive, porous, and even pleasant amenities.

The JFX is easily forgotten when the farmers' market is in session.
One relatively simple, but limited, first step to dissolve an elevated transportation corridor is to inject (more) programming under it, like flea and farmers' markets, recreational facilities (i.e. basketball and tennis courts), festivals, and any number of other community activities. Don't just relegate the space to parking or turn it into ambiguous “open space” – that only reinforces the viaduct's vacuum effect!

The wonderful Sunday farmers' market under the JFX is a great start, but it also reflects the limitations of the programming strategy: once the program ends, the border vacuum returns! The JFX vacuum is overcome for ~five hours a week (and only from April to December), but it returns in full force for the other 163 hours of the week. Furthermore, the market only occurs under a small portion of the JFX: the more viaducts a city has, the harder it is to inject enough programming to overwhelm all their border vacuums.

Any meaningful dissolution of an elevated border vacuum thus requires frequent, constant, sustained programming, which isn't always so easy to do. Not only that, but the programming requires the aforementioned mixed-use context to be viable. For example, there already are far too many vacant, graffitied basketball courts and concrete “open spaces” under viaducts in cities across the US (at least in those areas that haven't just been relegated to parking): the gloomy ambiance of the viaducts may dampen one's desire to use those amenities, but most sit empty because there are no (or not enough) adjacent neighborhoods to activate them. Contrary to popular belief, the neighborhood determines the success of the amenity, not the other way around!

So to support any meaningful viaduct programming, a city would need to introduce Jacobs' “extraordinarily strong counterforces” (discussed in the previous post) by building as much mixed-use infill as possible as close to the viaduct as possible. The ambiance from the mixed-use infill and viaduct programming might even overcome the noise from the cars or trains above. This outcome still might not appeal to some – many people quite understandably don't want to live near train tracks and highways – but it certainly wouldn't be an issue among youngsters hungry for street life: the banal viaduct would simply be overwhelmed by all the delightful stuff under and around it!

In addition to the adjacent infill and programming, it's important to introduce as many cross streets as possible under a viaduct. This allows pedestrians to pass underneath it in more places by eliminating superblocks. Right now, for example, there are only four crossings under the JFX on the east side of downtown, and, assuming the viaduct remained intact (though there are numerous possibilities for realignment or removal), additional cross streets could be introduced underneath it quite easily.

Of course, cross streets won't facilitate movement across/under a viaduct if they're boring, unpleasant, or (perceived to be) dangerous – they'd be no better than the forbidding pedestrian bridges and dreary overpasses across sunken highways. Furthermore, if there's nothing on the other side of a viaduct (or a sunken corridor) worth crossing for, then cross streets won't accomplish much either.

But assuming there is a viable urban fabric on both sides of a viaduct, then, in order to function as pleasant, safe, comfortable, and easy crossings, any cross streets underneath it would probably need to be lined with permanent programming akin to the bridge liners discussed in the previous post:

A Tokyo railroad viaduct doubles as a line of shops.
If a viaduct is surrounded by infill and crossed by multiple streets, the semipermanent programming underneath it can gradually be replaced with more permanent infill. Although this strategy was occasionally used in the US, it's far more common (and usually better done) abroad – Berlin's railroad viaducts are an excellent case in point. (I still remember a surreal experience in a supermarket underneath a railroad viaduct in Berlin – somehow the rumbling trains never managed to shake the bottles from their shelves!) Philly's Reading Terminal Market is another great example: built underneath a gigantic (former) train shed, the market is wonderfully integrated into the surrounding urban fabric. Even the cross streets underneath the train shed, albeit being a bit gloomy, are artfully lined with shopfronts.

Of course, highway viaducts and steel railroad viaducts are noisier than older masonry viaducts, so infilling underneath them might require soundproofing. On the other hand, the spaces under the former offer greater flexibility of use – you're not constrained by a series of fixed and relatively small arched bays.

So could this strategy apply to the JFX? So far the JFX border vacuum has only attracted more border vacuums: giant parking lots, an ever-expanding prison complex (plus the Juvenile Justice Center further south), a gigantic postal facility, and numerous facilities for the homeless (shelters, soup kitchens, clinics, treatment centers). It's difficult to imagine fixing this vast array of border vacuums, but they must be fixed if Baltimore wants a strong connection between the east side and downtown. Some of these facilities, such as Our Daily Bread, actually are good urban buildings (i.e. built out to the sidewalk without resorting to blank walls), so it is possible to work around them with dense, complex infill (Jane Jacobs' “extraordinarily strong counterforces” again) that might be able to overwhelm the current institutional programming.

Assuming the city (1) carefully surrounded the above border vacuums with appropriate infill (we'll look at specific solutions in upcoming posts on institutional border vacuums), (2) continued its admirable effort to increase the downtown population, and (3) undertook additional infill and adaptive reuse on the western edge of the JFX, then it might be possible to gradually fill the space under the JFX with permanent programming that could be supported by all the surrounding infill. The parking area that currently hosts the farmers' market, for example, could be rebuilt as a multipurpose market corridor and eventually turned into a permanent market.

A view of San Francisco's former Embarcadero Freeway in 1960.
Highway viaducts can also be dismantled and replaced with boulevards. Contrary to commonly-espoused doubts, the strategy has never yet resulted in traffic armageddon, so I think any doubts should be directed towards the far more important question of what exactly will replace the highway? Would the replacement be an urban amenity, like San Francisco's Embarcadero, or would it merely be a different kind of highway, like a single-use arterial?

For example, there's a longstanding proposal to tear down the elevated portion of the JFX and replace it with a boulevard that could allow East Baltimore to reconnect to downtown. I think the proposal sounds fine in the abstract, but its implementation raises some legitimate skepticism. Firstly, how would all the surrounding institutional border vacuums discussed above be addressed? Furthermore, many of the existing “boulevards” in Baltimore – like MLK Boulevard and President Street – have failed to attract abutting infill and pedestrians because they're essentially just glorified arterials, so would this failure merely be repeated? Replacing the JFX with an extended President Street (i.e. an extended arterial/collector road) would probably be a waste of time, money, and other resources that could be better deployed elsewhere.

If, however, the JFX was replaced with a true multiway boulevard that had the ability to attract abutting infill and street life, and if the institutional border vacuums in the area were successfully addressed, then its removal might indeed be a worthwhile effort. I've also suggested replacing the JFX with a boulevard+canal combo that could transform the currently-covered Jones Falls into a recreational canal similar to San Antonio's River Walk. (The proposal is admittedly rather idealistic because it would require additional expensive solutions for CSO, water pollution, and flood control problems, among many others.)

Again, as in the discussion on sunken corridors, most of the solutions above assume that the elevated corridors in question need to remain intact. But if they don't, their viaducts can be dismantled relatively easily and replaced with traditional urban fabric. However, if the viaducts have some intrinsic architectural appeal – like abandoned masonry or steel railroad viaducts – it might be a better idea to transform them into civic assets and neighborhood centerpieces.

The Promenade Plantée and Viaduc des Arts in Paris.
Paris' Promenade Plantée is an excellent case in point: a disused masonry railroad viaduct was transformed into a linear park and the archways beneath it were filled with artists' studios and shops. New York recently transformed a disused steel railroad viaduct into a beautiful linear park as well. Not every disused viaduct is worth saving, especially if repairing it would be prohibitively expensive, but most of them require just a little creativity to be turned into civic assets.

Of course, as discussed earlier, disused viaducts need to be integrated into the urban fabric just like active viaducts – mixed-use infill should be brought right up to the viaduct, multiple cross streets should be introduced underneath it, and any remaining space underneath it should be programmed or infilled. Furthermore, in order to avoid isolation, the amenity atop the viaduct (i.e. the linear park or promenade) should physically and visually connect to the underlying street grid in as many places as possible.

I hope you've enjoyed this final installment on transportation border vacuums – next time we'll move on to institutional border vacuums by discussing solutions for congregational facilities, like arenas, sports facilities, and convention centers.

- Marc Szarkowski

Wednesday, March 20, 2013

Dissolving Border Vacuums, Part 3

In the last couple of posts we looked at solutions for at-grade border vacuums, so now let's move on to sunken border vacuums, like highway and railroad ditches! Over the coming months we'll examine solutions for other kinds of border vacuums and see if they could apply to Baltimore.

The vicinity of Penn Station in 1917.
During the Industrial Revolution many cities discovered that the railroad was a mixed blessing: although they brought overall prosperity, railroad tracks tended to form downtrodden “Chinese Walls” wherever they passed through cities. If land was scarce and “air rights” valuable, it was possible to tunnel or deck over railroad tracks. But for the most part, and unlike many of their European counterparts, many American cities never really bothered to confront the border vacuums that railroad tracks caused – the phrase “the other side of the tracks” is arguably a lasting relic of our failure to address the vacuum effect of the railroad track. Unfortunately a century later this scenario would only repeat itself when highways were rammed through urban neighborhoods.

Who would want to walk here unless they had no choice?
Now that urban railroad and highway corridors are a fait accompli, is there any way to fix their border vacuums? Some cities buried these corridors in tunnels (i.e. Boston's Big Dig), but such fantastically expensive solutions are increasingly impractical. Other cities resorted to “it's the thought that counts” gestures, like the pedestrian bridge to the left, but these gestures didn't address the border vacuum problem at all. Fortunately, I think there's a feasible middle ground between “expensive and elaborate” and “cheap and useless.” To keep things reasonably concise, this post will only discuss solutions for sunken railroad and highway corridors – we'll get to their elevated corridors in the next post.

Existing ditches can be covered with concrete caps (aka decks, lids, platforms, covers, etc.), and, depending on their structure/reinforcement, the reclaimed space atop the caps can be used for buildings and/or parks.

However, extensive caps require ventilation systems, just like tunnels. And although highway and railroad caps are quite useful in places where development demand is strong and land value is high, they are still impractical in places with weak development demand. For example, it may be feasible to cap Philadelphia's Vine Street Expressway to aid the spread of revitalization northward from Center City, but it's unlikely that the Highway to Nowhere will be capped any time in the foreseeable future. After a half-century of economic depression in West Baltimore, it's now even less feasible to cap the highway as originally proposed.

Although it probably isn't economically feasible to build caps over the JFX segment from Preston to Chase Streets either, it might be possible to build them over the JFX/NEC segment from Maryland to Guilford Avenues. I think a cap might initially be viable only in the section immediately south of Penn Station (i.e. between Charles and St. Paul Streets), given the recent construction of the adjacent UB Law Center and the continued interest in infilling the parking lot to the north of the station. In time, perhaps additional adjacent caps (such as the section between St. Paul and Calvert Streets – which already has the Railway Express Building precedent – followed by the sections from Calvert to Guilford and Charles to Maryland) would become viable, further improving Station North's connection to Midtown.

If full caps aren't feasible, it may instead be possible to build bridge liners – lines of mixed-used buildings on both sides of a bridge. Bridge liners have been around for centuries, but they're a relatively rare feature in modern infrastructure projects, so I think they deserve a closer look.

The Cap at Union Station in Columbus, OH.
Since bridge liners don't require ventilation systems like extensive caps or tunnels, they're often much cheaper to build. For example, Columbus' Cap at Union Station, which connects the city's Short North neighborhood to the downtown, cost less than $10 million – the city/state paid just under $2 million for the bridge and the developer contributed another $7.5 million for the liner buildings, and the Cap is now profitable.

Columbus' Short North neighborhood has much in common with Station North: Both lie just to the north of their respective city's downtown (if, for the sake of argument, we lump Midtown and Mt. Vernon in with downtown, since they're seamlessly contiguous). Both neighborhoods are separated from downtown by highway/railroad corridors (but, unlike Baltimore, Columbus lost rail service in its corridor, hence their naming the Cap after a lost icon, Union Station). Both neighborhoods contain similar urban fabric – midrise apartment and commercial buildings, rowhouses, and industrial buildings. Finally, and most unfortunately, both neighborhoods sank into dereliction and street crime after WWII.

The same overpass before the Cap was built.
In the 1980s the Short North began seeing an influx of artists and bohemians, a phenomenon that's only just now appearing in Station North. But in the 1990s the state of Ohio proposed widening the highway (see left and above) and neighborhood advocates, fearing this would undermine the tentative progress in the Short North, insisted on a solution that would conceal the widened highway. The Cap at Union Station was the result.

A street-level view of the Cap.
As Blair Kamin noted, many Short North businesses have since experienced a dramatic increase in patronage migrating north from downtown. The bridge liners created a seamless, pleasant connection across what would have otherwise been an extremely unpleasant highway: “The cap is so successful that it has changed people’s expectations for highway bridges. The Ohio DOT’s plans for a new highway project include at least one highway bridge with a cap-style treatment. Other bridges will have foundations that allow caps to be built in the future.”

I think Short North-style liners could be effective (and perhaps even profitable) on the bridges that cross the JFX/NEC to connect Station North and Johnston Square to Midtown. Since the five north-south bridges (Maryland, Charles, St. Paul, Calvert, Guilford) and the three east-west bridges (Preston, Biddle, Chase) will eventually require repair or replacement, perhaps it might make sense to add liners to them when that time comes. Of course, the strategy would need to be coordinated with continued infill and adaptive reuse so there'd be a large-enough population to support the activities in the liners.

Bridge liners could reconnect Station North and Johnston Square to Midtown.
To initially strengthen the connection between Station North and Midtown, the Oliver Street offramp could be relocated to Maryland Avenue (thus allowing Oliver to be reopened as a normal street) and the Charles and St. Paul Street ramps downsized. Then the Charles and St. Paul Street bridges could be lined, and, depending on their success, the Calvert, Guilford, and Maryland bridges could be lined next, followed by the Preston, Biddle, and Chase bridges.

I think liners would extend Midtown's vibrancy across these eight bridges and finally allow meaningful, significant revitalization to spill over into Station North and Johnston Square. The adaptive reuse and infill potential of the many vacant buildings and lots in these two neighborhoods would improve dramatically as land values correspondingly increased.

Of course, the cap and liner solutions assume that the sunken corridors in question need to remain intact. But what if they don't? The Highway to Nowhere is a case in point: it was never connected to the interstate highway system, so there's no need to maintain its current dimensions. Building caps or liners would be a waste of money: why dedicate considerable resources to covering something that can just be dismantled?

The Baltimorphosis vision for the Highway to Nowhere.
Dismantling a sunken corridor opens up numerous possibilities for reuse. For example, I prefer the Baltimorphosis proposal for the Highway to Nowhere over the official plans for (partially) capping it: the corridor is ideally suited for the future Red Line, but that doesn't mean its ditchlike configuration need be maintained. There's no reason why the sunken highway couldn't be substantially downsized or eliminated and the reclaimed space used for any number of things, from mixed-use transit-oriented infill to linear parks to some combination thereof.

Sometimes there are railroad corridors that run either at the same level as the surrounding urban street grid or above it on solid earth embankments (i.e. not on viaducts). Is there any way to fix their border vacuums?

A Tokyo railroad corridor doubles as a bike/pedestrian/shopping lane.
It's possible to punch new streets (or to extend existing dead-ended ones) through embankments to increase the number of connections across/under them. This strategy would probably need to be coordinated with Jane Jacobs' “extraordinarily strong counterforces”: “Population concentration ought to be made deliberately high near borders, the blocks close to them should be especially short and their potential street use extremely fluid, and a mixtures of uses should be abundant (268).” In addition to bringing the mixed-use fabric as close to a railroad corridor as possible, the corridor itself can be improved by incorporating amenities like bike paths and market streets into the right-of-way. This strategy has long been used in Tokyo, and I think it's a strategy US cities ought to investigate.

So, for example, the section of the NEC between Broadway and Orangeville could be turned into a civic asset if an extension of the metro to Bayview and/or the upgrading of MARC service to metro-like frequencies became realities. By lining both sides of the NEC with streets that could double as bike routes and promenades, enclosing these streets with mixed-use infill, and introducing as many cross-streets as possible under the NEC (to allow for small blocks and frequent crossing), it could be turned into one of Kevin Lynch's “seams.” Not only would the corridor offer frequent, convenient metro and/or MARC service (and thus serve as a TOD attractor), it'd double as a leisurely cycling and walking route.

Next time we'll look at solutions for elevated borders (like highway and railroad viaducts), so stay tuned!

- Marc Szarkowski

Wednesday, March 6, 2013

Dissolving Border Vacuums, Part 2

In the last post on at-grade border vacuums we discussed solutions for vacant lots and parking lots, so this time let's examine solutions for arterial roads. Over the coming months we'll examine solutions for many other kinds of border vacuums and see if they could apply to Baltimore.

Despite its misleading name, MLK Boulevard is a repellent arterial.
After WWII the arterial road became the common solution for accommodating urban through traffic. Unfortunately arterials devolve into formidable border vacuums that interrupt the continuity of urban fabric – they're essentially an inappropriate solution for urban areas. Baltimore has many notorious examples that seem to frustrate everyone, whether they're pedestrians, cyclists, drivers, transit riders, or nearby residents and businesses: President Street, Pratt Street, Russell Street, MLK Boulevard, and large portions of North Avenue, Mt. Royal Avenue, Howard Street, Light Street, Dolphin Street, Fayette Street, the list goes on and on.

Is there a way for thoroughfares to accommodate through traffic without turning into border vacuums? In this post I'll posit that some of the above arterials might be better urban neighbors if they were rebuilt as center-median or multiway boulevards. But before we discuss the specifics of these two kinds of boulevards, let's look at some more modest prerequisite solutions first:

Pedestrians, cyclists, and drivers have all experienced the frustration of long waits at certain crosswalks/traffic lights. I've noticed that I tend to avoid crossing arterials with long waits unless I have no choice: why suffer the difficulty and unpleasantness of an arduous crossing expedition? Poor signal timing (long green-yellow-red cycles between the “walk” signals) tends to exacerbate the border vacuum effect of arterials by making it too arduous to cross them on a casual basis. So pedestrians either resort to jaywalking or gradually stop crossing the arterials, which only solidifies their border vacuum effect.

Therefore one easy, but limited, strategy to dissolve the vacuum side effect of an arterial is to adjust its signal timing to shorter cycles, possibly 60 seconds or less. This reduces waiting time for pedestrians, thus allowing them to cross more easily and frequently.

Although this strategy is quite useful in encouraging pedestrians to cross arterials that already have adjacent pedestrian activity, like Pratt Street, it can't induce pedestrian life in and of itself, particularly if there's nothing worth crossing for/walking to! For example, improved signal timing would do little to reduce the vacuum side effect of MLK Boulevard. To create something worth walking to, you'd have to build the mixed-use infill we discussed in the previous post!

Enclosing arterials with buildings can make them feel narrower.
Another subtle strategy to reduce the vacuum side effect of an arterial is to enclose it with infill buildings tall enough to make the arterial feel narrower than it actually is. So the wider the arterial, the taller the enclosing buildings would need to be. In the photo on the left, you'll notice that the arterials in both scenes are of comparable size, but that the second one feels more intimate because it was enclosed with buildings that form a “street wall.” While a comfortable height-to-width ratio of enclosure – the height of the enclosing buildings in proportion to the width of the arterial they're on – can vary, it seems that a 1:1 ratio feels best (see page 45) for mixed-use thoroughfares and that even more intimate ratios, like 3:1, are possible for residential streets.

If it's not possible to provide enough (or tall enough) infill to offer a sense of enclosure, street trees can be used instead. It's best to use hardy species that can form canopies quickly. Unfortunately sometimes dinky ornamental species are used – akin to the fillers in supermarket parking lots – and these don't offer a sense of enclosure at all. Street trees aren't just supposed to be decorative; they need to enclose arterials just like buildings would.

It's possible to (re)introduce cross streets to arterials to enable pedestrians and cyclists to cross them in more places. This strategy also breaks up superblocks into smaller blocks that are more conducive to street life, as Jane Jacobs discussed in Chapter 9 of The Death and Life of Great American Cities. In fact, there already are proposals for doing exactly this to a portion of MLK.

Arterials can also be “rightsized." This involves the narrowing and/or removal of lanes (like downsizing to 10-foot travel lanes and 8-foot parking lanes) and repurposing the reclaimed space for bike lanes, bus lanes, street trees, and/or wider sidewalks. So, for example, if State Center was redeveloped (we'll get to that proposal in a future post!), there's no reason why the maze of arterials in that area (Howard, MLK, Preston, Dolphin, etc.) couldn't be substantially downsized.

As Allan Jacobs notes in The Boulevard Book, a boulevard is essentially mixed-use, whereas an arterial is single-use: “The boulevard directly addresses the problems posed by the coexistence of through traffic and access to abutting land uses on major urban thoroughfares. It allows these seemingly contradictory but often complementary needs to coexist in the same corridor. Analogous to mixed land uses – another victim of planning and development procedures since WWII – the boulevard is a mixed-use public way that is by its very nature complex (5-6).”

Just as we inappropriately imported alien development patterns into cities (single-use zoning), Jacobs argues, so too did we import alien transportation patterns (single-use arterials) into cities. In the last few decades we've reacquainted ourselves with mixed-use urban infill, so perhaps now we should reacquaint ourselves with mixed-use transportation corridors like boulevards.

Drawing of a center-median boulevard (Unter den Linden) by Allan Jacobs.
Center-median boulevards have – you guessed it – a median running down their center! Depending on its width, the median can accommodate a simple row of trees, a transit line, or even a promenade/park – Eutaw Place and Broadway, albeit being badly butchered after WWII, are good examples of the latter. The carriageways on either side of the median are usually divided into two travel lanes and one or two parking lanes in each direction.

I think North Avenue, particularly the section from Pennsylvania Avenue to Greenmount Cemetery, could benefit from a center-median configuration, and indeed there are several suggestions for doing just that. While the proposals vary in their particulars, they share some crucial features: the (re)introduction of curbside parking to buffer pedestrians from traffic, the enlargement of the currently-useless shrubbery median into a fully-programmed promenade/park/square, and the downsizing and/or elimination of superfluous travel lanes.

However, we should never underestimate just how unpleasant it is for pedestrians to be near heavy traffic. Boston's Rose Kennedy Greenway is a case in point: the city shot itself in the foot by sandwiching prime urban land in the middle of a new arterial. Even though much of it is 100 to 200 feet wide, Boston's “glorified median strip” still can't overcome the unpleasant traffic on both sides. Lesson number one: people need more than meaningless “open space” to enjoy a median, and to its credit Boston is adding programming to the Greenway to distract people from the surrounding traffic. So I think a North Avenue median park would likewise need to be intensely programmed with activities to be successful.

Secondly, rather than waiting for saplings to mature to establish a protective screen, the median park would probably need to be lined with substantial trees from the beginning. (Note that this is exactly what's proposed for the renovation of Mt. Vernon Place.) Simply relying on elegant furnishings probably wouldn't be enough – although Eutaw Place and O'Donnell Square have just that, they feel nicer because they don't have nearly the same traffic as North Avenue.

Finally, a median park would need to be coordinated with infill that offered the sense of enclosure discussed earlier. So, for example, Madison Park North would need to be replaced with traditional fabric. The northern edge of Bolton Hill, having turned its back on North Avenue, would also need to be infilled: Spicer's Run would need to be wrapped around North, and the exposed railroad tunnel at Mt. Royal Avenue would need to be capped and infilled, along with the parking lot immediately to the west. The numerous “missing teeth” along the avenue in Station North (particularly the parking lots around the BCPSS HQ) would need to be infilled as well.

Compare this old photo of Eutaw Place to the same area today!
Existing center-median boulevards can also be improved with better infill. For example, there are plans to replace Eutaw Place's Pedestal Gardens and Bolton Hill Shopping Center with traditional infill akin to Spicer's Run (which did a good job reconnecting to Eutaw if not to North). To further dissolve Eutaw's vacuum effect, the proposal might also consider downsizing McMechen Street and incorporating corner stores (to further encourage pedestrian crossing). Of course, replacing missing trees, statues, benches, fountains, gardens, pavilions, and pavements would breathe life back into Eutaw Place as well.

Drawing of a multiway boulevard (Avenue Montaigne) by Allan Jacobs.
Unlike center-median boulevards, multiway boulevards separate through traffic from local traffic and use the latter to extend the pedestrian realm and buffer it from the through traffic. A multiway boulevard thus contains three carriageways: a central carriageway for through traffic (usually two lanes in each direction, plus transit lanes if there's room) separated from two access lanes (one on each side) by tree-lined medians.

As Allan Jacobs notes, the access lanes must be built for low speeds – one 7'-10' travel lane and one or two 6'-8' parking lanes – to form a comfortable pedestrian realm: “The main feature that makes multiway boulevards safe and livable is the extent to which a clear pedestrian realm emerges between the buildings and the medians. This realm is structured as a complex area where cars are allowed but pedestrians dominate. The multiway boulevard allows access movements, through movements, and pedestrian comfort to coexist on the same street; it retains both traditional uses of the street – as a movement channel and a meeting place – without having to specialize in either one (111).”

By concentrating through traffic in a relatively narrow core (four travel lanes @ ~40-45 feet) and extending the pedestrian realm across the access lanes and medians, a multiway boulevard reduces the vacuum effect of an arterial by subtly downsizing it to the same dimensions as the average urban street (two travel lanes and two parking lanes @ ~40-45 feet), which allows for better signal timing (shorter cycles) and frequent pedestrian crossing.

Earlier we discussed how enclosing arterials with buildings could make them feel narrower. However, there's a caveat: just as pedestrians avoid walking along arterials, so too do buildings tend to shirk them. This is why the neighborhoods along MLK have all turned their backs on it via shrubbery buffers, berms, and walls, and why buildings along older thoroughfares that were turned into arterials (like North Avenue) fall into a downward spiral of dereliction. By serving as a buffer from through traffic, a center-median boulevard's parking lanes can create a pleasant enough environment for pedestrians and abutting buildings, but, as Allan Jacobs discussed, a multiway boulevard's access lanes and medians do an even better job at this. The short access lane and park median on the southwest side of Mt. Royal Avenue in Bolton Hill is a good example, though the avenue itself leaves much to be desired.

Therefore, I think MLK should be converted into a multiway boulevard (four central travel lanes flanked by access lanes with parking) so it could attract pedestrians and abutting infill, thus stitching West Baltimore back to downtown by functioning as a “seam.”

Next time we'll examine solutions for sunken borders (like highway and railroad ditches), so stay tuned!

- Marc Szarkowski
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