Thirty-seven percent of Bostonian households (37%!) don’t own a car.  But that still leaves most of us, especially suburban and rural dwellers, car dependent – forced because of the individually-varying distances between our homes and workplaces and shopping/socializing destinations to use individual vehicles to get around.  Our transportation system has to acknowledge and service that reality.

While ignoring the current need for cars is both functionally and politically self-destructive, ignoring the need to “bend the curve” of future demand would be even worse. While Massachusetts policy regarding transportation infrastructure has begun recognizing these realities, and actual road design has significantly improved, the gap between vision and reality is still enormous.  And a key reason is the lag between new ideas and their incorporation into the transportation profession’s culture.  We need to change some of the metrics and defaults that shape road engineer’s decisions to nudge them towards more creative and complete incorporation of the new vision and values into their work.



Our current car-dependency is unsustainable – urban areas, major roads, and pinch-points through the region are already congested will only get worse, hurting both business profits and personal life.  Transportation greenhouse gas emission are now the state’s biggest contributor to potential climate disaster, and the environmental damage of producing fossil fuels continues to grow.  Even if we had the space, building more roads or even expanding our existing ones will just induce more people to drive – until those lanes, too, are full.  Current demand is also a poor indicator of people’s preferences. Just because someone drives to work now doesn’t mean they want to drive to work. For many people, it means that they don’t have a reasonable or safe alternative, whether it be taking transit, walking, biking, or a combination.  Most surveys show that people would rather not drive, or at least not drive under current conditions.

Continued economic growth and environmental sustainability requires that we create infrastructure that better matches the ways that people would actually like to travel, and that “nudges”, perhaps even incentivizes, people towards less destructive methods of travel. 



Public sector transportation officials, their engineering staffs, the private-sector consultants they hired to do the design, the construction firms who did the work – all of them had spent their lives, from their professional training to their work-life experience, building roads with the Interstate as the model of what a “real” road ought to be.  (Not so many years ago, a veteran transportation official told me that “every driveway secretly wants to grow up into a highway.”)  The default assumptions were that motor vehicle traffic took priority over other road uses; that maximizing motor vehicle capacity and speed was the number one goal and anything that interrupted or slowed the traffic flow was bad.  It was also considered necessary, and smart, to build in a “margin of safety” to compensate for possible driver error – so lanes had to be kept wide, curves gentle, and distracting street-side activity eliminated.

While many of these ideas are sound and necessary for Interstates, today’s emphasis on “livability” as the key to municipal well-being implies a nearly opposite vision for non-highway roads.  Pedestrian safety and bicycle functionality are given equal weight to car movement.  Speed is seen as dangerous, and simply gets cars quicker to the next stop sign.  Making roads feel comfortable as speeds higher than either the posted or the desired “target” mph makes them more dangerous rather than safer.  Roads and the abutting land are valuable public property properly useful for things other than transportation and therefore sometimes the best use of a street is not allowing for as much parking as possible.  And more.

For a long time, road design was shaped by the Internet model and car-centric values.  As times changed, public values evolved, and advocates became active, every project became a battle ground.  But f the same issues in every project is like running in place, a lot of work but little forward motion.  The obvious need for system change pushed progressive transportation advocates to quickly expand from project-by-project critiques to overall policy. 



The amazing thing is that, to a great extent – at least in Massachusetts and a few other states – the fight over policy was won.  It is a dramatic change – MassDOT, Boston, and other cities around the Commonwealth have adopted Complete Streets principles, set up Pedestrian and Bicycle plans, and are increasingly using Vision Zero as a guide.  The default starting points for lane widths, speed limits, bike facilities, walk signal timing and dozens of other details have all been shifted in favor of rebalancing street layout to make travel safer for walkers, cyclists, and bus riders.  Most astonishingly the “standard model” for bicycle facilities has leaped from wide car lanes to in-road (“door zone”) bike lanes to parking-protected, curb-protected, or flex-post-separated bike lanes.  Several cities are now expanding their multi-use path systems, often based on “rail-to-trail” conversions, and investing in major off-road greenway networks. By combining multi-use paths, protected on-street bike lanes, and low traffic slow speed neighborhood streets, cities are also now looking to create low-stress bike networks that will allow people of all ages and abilities to safely bike wherever they need to go.  (The metro-core’s  Emerald Network initiative, on whose Executive Committee I serve, is an example, as is the eastern Massachusetts LandLine project led by MAPC.)

MassDOT has taken steps to implement these policies.  Building on its national leadership in “Context-Sensitive Design”, new training sessions about Complete Streets have been given to Central and District staffs and made available to both municipal transportation planners and private consultants.  A Complete Streets incentive funding program has been set up.  A design guide for separated bike lanes has been issued.  Internal committees such as the Design Exception Review Committee reviews projects and enforces the inclusion of at least minimum pedestrian and bicycle facilities.  State-wide master plans for Bicycling and Walking are in process.  Public input protocols have been strengthened and advocates are often brought in for discussion at the conceptual design stage instead of being forced to react after the fact to already-developed plans.  Very few new state projects lack at least some attention to pedestrian, bicycle, and transit rider needs.



Of course, as any trip quickly shows, there is a lot that still needs to be done.  While the default assumptions have improved, official guidelines still – correctly – leave a great deal of latitude for case-by-case variation based on the designing engineer’s professional judgement.  And, despite the influx of new people into the profession, as well as the retraining of more veteran staff, old habits and feelings die hard. Often, designers’ professional judgement is still shaped by old assumptions.  So, without intending to undermine policy, most engineers start a road design by figuring out how to accommodate the maximum number of current and future car traffic -- an estimating process that some people feel tends to overestimate 20-year traffic volumes— and only then try to squeeze in pedestrian and bicycle facilities.  And often when they do try to add pedestrian and bicycle facilities, instead of reallocating available space they state a need to widen the right of way, which is often physically or financially impractical, leading to a decision to shrink or degrade the non-car accommodations.

This sometimes happens because a stand-alone project does not have good pedestrian/bike connections on either side, allowing the designer to feel that it makes no sense to include space-consuming non-car facilities that go nowhere – forgetting that you have to start somewhere.  It sometimes happens because our cities (not to mention suburban and rural areas) still have so few state-of-the-art examples of non-car-prioritizing roads that it is hard for people to internalize an awareness of the huge safety, functionality, and environmental advantages of pushing their designs for maximum modal rebalancing. It sometimes happens because of resource limitations:  most engineers start a design with an understanding of what they can pay for; plenty would love nothing more than to generate amazing designs if only their budget would allow it.  And it sometimes happens because it is too easy to say that the full-route changes needed to make end-to-end walking and bicycling safer require a future, major project so aren’t safe to be done on a piecemeal basis today – except that the expensive future project never comes.



Most fundamentally, however, pedestrian and bicycle comfort are shortchanged because the primary role of a project is still often seen as adding more capacity for cars, and without doing that to the maximum extent, project designers feel that they have not done their job. It also doesn’t help that the traffic models and computer simulations that engineers use to test their designs mainly analyze car throughput. So, while eliminating a travel lane may mean that there is now space to add sidewalks or bike lanes, the simulation only shows reduced improvement in car throughput.  (These simulations also neglect the fact that adding car capacity does not actually reduce congestion over time, as new trips that would not have occurred otherwise often fill the additional roadway capacity.)

As an experienced transportation engineer once told me: “Most engineers start a road design by defining the problems [which almost always are car related].  Then they develop solutions to those problems. This problem is usually one of three things – 1) there is an unsafe condition generally characterized by a high number of vehicular crashes, 2) there is a poor level of service generally characterized by vehicular delay, or 3) the condition of the facility is poor and requires rehabilitation.  Some projects focus more on the needs of pedestrians, such as our Safe Routes to School projects, and others focus more on the needs of bicyclists, such as those for off-road shared-use paths, but for most projects, the primary “problem” to be addressed is vehicular-focused.  Thus, the primary solutions to those problems are usually vehicular-focused.  Making other changes that aren’t necessarily flagged as problems or as reasons for the project in the first place can often be viewed as a secondary effort.  Trade-offs that that lessen the solution to the identified “problem” are often hard to justify.  Perhaps there-in lies the true “problem”, that pedestrian and bicycle facilities (or lack thereof) are not seen as problems.  At least they are not identified as primary problems that are a reason for the project in the first place.  Almost all projects are initiated because of problems with vehicle safety or congestion.  Thus, the designers’ primary goal is to fix those problems.  And if they don’t, then the project is not necessarily effective.”

Charlie Denison, chair of LivableStreets’ Advocacy Committee, eloquently expressed the frustrating inadequacy this creates in our road designs.  Writing to the MassDOT Design Exception Review (DER) Committee, Denison said:

“It is disappointing that we are once again left fighting for scraps for pedestrian and bicycle infrastructure. I have recently read multiple DER reports where the desired number of travel lanes are provided at maximum or close to maximum widths, and then inability to widen the roadway due to physical constraints or cost is used to then say that minimum pedestrian and/or bicycle facilities are not feasible. Project designers should be analyzing various combinations of travel lanes at various widths and should be encouraged to bring travel lanes (and inside shoulders) down to minimum widths if necessary in order to provide pedestrian and bicycle facilities. Minimum pedestrian and bicycle facilities should not be optional, even in cases additional travel lanes or wider travel lanes may be desirable.”



Recognizing this problem, MassDOT also deserves credit for beginning to re-examine the current guidance it gives its staff, designers, and municipalities about lane widths and pedestrian/bicycling accommodations (a document charmingly known as E-14-006).  The key impact of these default widths is that anything outside the suggested dimensions requires the designer to apply for a “design exception” approval – which requires extra time and work as well as some sophistication on the part of the traffic engineer.  Not surprisingly most road projects follow the suggested defaults even though, in the words of one MassDOT official, it’s the “design exception that helps produce exceptional projects”.  (Ironically, he was referring to excepts that pushed further towards Complete Streets ideals while the majority of actual exception requests are to do less.)

For example, currently, if a road is designated as being part of the National Highway System (which includes nearly all major roads in the state) any effort to bring traffic lane width down from the current more-than-necessary 12 feet default minimum requires a Design Exception application, analysis, and approval.  On non-NHS roads, the trigger is any attempt to reduce lane width on “Arterials” – the roads that carry the most traffic -- below 11 feet, even though research shows that most roads are just as safe at 10.5 feet’ or even 10 feet.  (“Collectors” have an exception trigger of 10 feet, local roads are 9 feet.)

Ironically, as traffic engineers begin to implement Complete Streets designs, the current E-14-006 rules generate increasing numbers of Exemption Requests, clogging up the system and slowing down projects. This perception was, in fact, the original reason for the creation of the Design Exception Review committee.  Reducing lane width requirements is a win-win for both road users and MassDOT.  (However, as Charlie Denison has also written, reducing the default width of sidewalks or bike lanes might allow road planners to leave car lanes unnecessarily wide.  He suggests that it is time to require a design exception for using the shoulder as a substitute for a real bike lane, and that speed limit, design speed, and traffic volume should be included as “context” in determining the default width of bike facilities.  In addition, “while increasing the default sidewalk width is good the most important dimension is actually the usable clear width – for example an 8-foot sidewalk with a tree pit likely only has about 4 feet of usable width.”)

According to one MassDOT official, the agency is now “examining all of our project development processes to look for efficiencies and the fate of E-14-006 may also be tied to that effort.  We are basically trying to find ways to make key project decisions early to help avoid delays later.  Agreement on the roadway cross section is fundamental to this. [But no one is yet] sure how this will all play out.”



One piece of good news is that we are seeing more sidewalks and bike lanes in MassDOT projects than we have in the past. We are seeing projects with 5’ shoulders where we would have seen 4’ in the past, and projects with bike lanes (and sometimes now even physically separated bike lanes) where we would have only seen shoulders previously. The bad news is that at intersections and pinch points, we are still often seeing substandard facilities.

For example, there have been numerous projects where a roadway is proposed to be widened, in part to provide sidewalks and bike lanes. However, as the road crosses under or over a bridge or overpass, there often isn’t room to widen it unless that bridge or overpass is also rebuilt. That is rarely actually done, understandably, due to expense. Project designers should be adjusting the width and/or number of travel lanes through the constrained section in order to allow for pedestrian and bicycle facilities to remain continuous through the pinch point. What we see more often than not, however, are sidewalks narrowed severely or omitted from one or both sides of the street, and bike lanes removed or shoulders narrowed so that they are not wide enough for bicyclists to use them, forcing bicyclists to share a travel lane with motor vehicles through the constrained area. Omitting sidewalks or bike lanes, even through a short stretch, severely hampers the usefulness of the bicycle facilities along the remainder of the project. Yet, Design Exceptions are regularly requested and granted for these substandard facilities.

Similarly, design proposals frequently include bicycle-accommodation shoulders that drop off through intersections, so that additional lanes can be added to provide motor vehicle capacity at the intersection (for example, left turn or right turn only lanes, and sometimes even additional through lanes just through the intersection itself.) If a bike facility is to be useful, it needs to be continuous. LivableStreets regularly advocate for 5’ minimum bike lanes that continue through intersections, reducing the need for bicyclists and motorists to negotiate in shared lanes, although we often do not end up with that result.



While Complete Streets is a powerful vision for road design, in practice it still starts from a set of pavement layout specifications.  The original motivation, one that needs to be repeatedly remembered, is to make movement safer, easier, and more inviting for people – for all people using all methods of travel.  In response to a new National Transportation Safety Board (NTSB) report about the dangers of speed, the National Complete Streets Coalition has urged Departments of Transportation to use a “’safe systems approach’ that considers crash experience, speed limits, and vulnerability of people walking and bicycling to produce a comprehensive solution for reducing crashes that benefits everyone — not just those driving.” 

The advice is worth following for all aspects of road design.  Given our current imbalance in favor of car movement, creating a Complete Street – as well as a more economically and environmentally sustainable transportation system – requires an explicit mandate from the highest levels of government and MassDOT to select projects and engineer solutions that help shift the mode share needle.  


Thanks to Tom Dipaolo, Jason Degray, and Charlie Denison for their extensive and insightfully critical feedback on earlier drafts.


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