Office of Planning, Environment, & Realty (HEP)
While visioning, planning, and partnerships can help transportation planners develop integrated solutions that respond to community desires, delivering livability at the project level requires new design approaches. Transportation projects that provide multimodal mobility and support compact mixed-use development patterns must incorporate an overall network approach linked to urban design and a detailed facility design that balances use by all modes. Designing for livability requires understanding who will use the system, including them in the design process, and incorporating their input into final design. Livability-oriented design takes cues from the planning and project development process, and is often explored at the concept level during visioning. Land use plans and policies, community characteristics, and local and regional policy goals can help define transportation facility design priorities.
A well-executed design process can build on early efforts in visioning, planning, and integration of transportation, land use, and housing, bringing them closer to implementation. Conceptual design is often where many of the most creative solutions are developed. Exploring alternative design concepts in the visioning process can help develop broad goals and objectives, while helping participants to understand the challenges and constraints of transportation facility design, engineering, and constructability. Many of the case studies faced significant challenges posed by existing conventional design guidance and regulations, requiring repeated efforts to get design exceptions. In some cases (Charlotte and PennDOT), the agencies' experience with integrated planning has led to development of new approaches, policies, and standards.
The design phase of a project is where integrated project design can affect project cost and delivery schedule, but is also where innovative design solutions can develop more cost-effective solutions for a phased network approach. The following challenges are often faced by agencies working to apply a more livability-based approach to project design.
The case studies that follow are intended to show how these issues have been addressed in different community contexts.
Hillsborough Street in Raleigh, NC, served a fundamentally urban, multimodal role in the community but had been assigned a role of moving high volumes of traffic. It is one of a limited number of east-west connections between Raleigh's central business district and Durham and Chapel Hill, its partner cities in the region. This case study demonstrates that community objectives sometimes conflict with a roadway's designation, but that appropriate design can help meet both community and transportation system goals.
As one of Raleigh's main connections to the expressway system, it was attempting to serve the dual roles of business main street and urban thoroughfare; it did not serve either of them very well. Increased vehicular traffic led to the road being widened to a four-lane, undivided cross section. Vehicle conflicts on the four lanes caused traffic flow problems: a left-turning vehicle waiting against oncoming traffic would block the inner travel lane, while a stopping bus would block the outer lane. The focus on vehicle movement compromised bicycle and pedestrian safety, a critical concern in light of the volumes of nonmotorized traffic expected on the main business street adjacent to a major university campus. Although designated for through movement under the State highway system, the corridor's real needs included safely accommodating pedestrian and bicycle movement, incorporating streetscapes favorable to local business, and serving as a public edge to the educational campuses it serves.
The roundabouts at the Hillsborough/Pullen (lower left) and Oberlin/Pullen (upper right)
intersections reflect the variety of design options available in just this one type of intersection.
Higher-volume, multi-lane roadways can still be accommodated with roundabouts through
the use of two lanes in the circulating roadway.
Source: City of Raleigh, 2007.1
Community and civic stakeholders had long identified the existing street design as a challenge to the corridor's long-term success. In the late 1990s they launched a collaborative effort with the City of Raleigh and the North Carolina Department of Transportation (NCDOT) to begin changing the street's profile to better reflect its role as a main street for North Carolina State University (NCSU). One of the key organizations in this effort was the Hillsborough Street Partnership (HSP), a coalition of community members, businesses, civic organizations, and students. HSP began developing concepts for streetscape design and traffic calming along Hillsborough Street in 1999 and partnered with the City of Raleigh soon after.
The HSP-led team identified principal concerns, including a high rate of pedestrian-vehicle accidents (four times the average for North Carolina State highways), lack of dedicated bicycle facilities and infrequent use of designated parallel bicycle routes, and problems with traffic flow when commuting and business traffic combined in peak travel hours. With city support, the team conducted a feasibility study to explore design options and test roadway performance using corridor simulations. The city's involvement in a collaborative design process helped bridge the gap between the community-led effort and NCDOT, which retained control over the roadway.
The resulting two-lane road design used roundabouts to preserve traffic capacity, manage intersection congestion, and reduce delay while improving pedestrian crossing safety. At the time of design, Hillsborough Street carried 26,000 cars per day, with higher numbers forecast for the future. The reduction from four to two through lanes added on-street parking, bicycle lanes, and a landscaped median to restrict midblock left turns and provide pedestrian refuge in midblock crossings. Due to the high traffic volumes, roundabouts were used to improve traffic flow while maintaining turning movements. Since the inner travel lane on four-lane roads is frequently blocked due to left turns, the Hillsborough design limits direct left turn access into business driveways. Turning traffic passes its destination, uses a roundabout to make a U-turn, and makes a right turn at the destination.
Due to budget reasons, all the proposed roundabouts were not constructed. Several minor intersections use traffic signals, but the central raised median is replaced with left-turn lanes to preserve movement on the travel lane. At intersections without high levels of delay, modeling demonstrated that signalized intersections could handle traffic, saving funds to improve pedestrian crossings. The roundabouts critical to traffic operations at major intersections were constructed.
The reduction of travel lanes restored space for on-street parking, bicycle lanes, and expanded sidewalks. The on-street parking allows for adjacent properties to maximize buildable area without needing to add on-site parking and circulation. A key factor was NCDOT's acceptance that the road did not need to serve the same function that its classification might suggest. This was supported by the 2001 feasibility study, which estimated that only around 30 percent of Hillsborough Street traffic was through travel. The construction of Western Boulevard and the extension of Wade Avenue as a limited-access arterial had already provided east-west mobility. While NCDOT maintains jurisdiction over Hillsborough Street, it has accepted that the local function of the road should be a priority, allowing the proposed design.
In some cases on Hillsborough, property constraints and project cost led to the continued
use of conventional signalized intersections. However, it is still possible to enhance these
kinds of intersections to make them more livable: the use of curb extensions (on the
upper-left corner of the intersection) and clearly marked crosswalks improve the pedestrian experience.
Source: City of Raleigh, 2007.2
Construction began in 2009, with completion expected in 2010. The project converts Hillsborough Street to a two-lane, median-divided facility with on-street parking on both sides, a 7-foot-wide raised median, sidewalk bulbouts at intersections and midblock locations, and several pedestrian signals. It also includes replacement of water and sewer utilities and light-emitting diode (LED) street and pedestrian lighting. These increased project costs, but the city had planned to undertake them regardless of any streetscape work on Hillsborough. The original designs featured newly emerging concepts such as roundabouts, pedestrian countdown crossing signals and midblock crossings, which are now regarded as standard practices. The bicycle lanes originally recommended in front of the NCSU campus have been designated as shared-use arrow pavement markings ("sharrows") but are still being considered for bicycle lanes (as of Guidebook publication).
Local government involvement is essential to the success of community-led projects, especially when a State agency has jurisdiction over the project. North Carolina retains control over most roadways. Raleigh is North Carolina's capital and second largest city, and NCSU is one of its premier educational institutions. Having a strong base of municipal and institutional support helped advance the project through design and construction.
The project also demonstrates the effectiveness of roundabouts in reducing pedestrian-vehicle conflicts and untangling key operational complications of urban streets. Roundabouts allow free low-speed movement without stopping traffic like signalization, while separating pedestrians from the direct path of turning vehicles. Initial observations suggest that the roundabouts constructed from the original concept plan are meeting traffic flow objectives while greatly improving pedestrian conditions. The Pullen roundabout inside the NCSU campus has performed successfully and without accidents since its construction.
Hillsborough Street provides a valuable lesson for urban through corridors in downtowns or adjacent to campuses or activity centers that see high amounts of non-motorized travel. The design accommodates high traffic volumes managing congestion while improving pedestrian access and safety. It also demonstrates that motorized travel in urban environments does not necessarily require higher speed conditions to maintain capacity.
Capacity enhancement projects such as roadway widening can generate unintended impacts on adjacent properties, potentially reducing their usability and access. This is one of the greatest sources of controversy over widening projects: They can enhance vehicular mobility, but at the expense of the surrounding community, including creating barriers between neighborhoods. The more a road is oriented to vehicular mobility, the less equipped it is to support walking, wheeling, and transit. Widening projects can also limit feasible land use options, potential for downtown economic revitalization, and quality of life. Roadway widening projects are typically proposed when a transportation agency has determined that traffic on a road exceeds available capacity. For some agencies, policy requires that capacity deficiency problems on a road must be addressed on that road only, especially if it is part of the State system.
Palm Canyon Drive, a primary commercial arterial in Cathedral City, CA, shows how integration of roadway and urban design can incorporate future land use plans and preserve future capacity. The project preserved a five-lane cross section as the principal roadway, while separating on-street parking and business access from through travel with a series of access lanes, using a modified form of the model of European and City Beautiful boulevards.
The Palm Canyon Drive reconfiguration began as two distinct planning efforts: redevelopment of downtown Cathedral City and a Caltrans project to add capacity to Palm Canyon Drive (then California Route 111) by widening from five to seven lanes. The City of Cathedral City had retained a consulting team to assist in selection of a new City Hall site. The city team joined discussions about Palm Canyon due partly to local interest in reorienting the town's historic center along Palm Canyon, and partly in resistance to plans for another widening project on Palm Canyon. The historic center had gradually disintegrated due to multiple widenings throughout the middle and late-20th century. The city's primary interest in Palm Canyon was revitalization. Through years of disinvestment that followed property impacts from roadway widening, the corridor had declined in appearance and value, and effectively deterred investment in the neighboring Coachella Valley resort communities of Palm Springs, Palm Desert, Rancho Mirage, and Indian Wells.
The original intent of the Palm Canyon multi-way boulevard
design was to separate local traffic from regional through
traffic, thus preserving vehicle-carrying capacity on an
important regional road. However, designs for the street
incorporated the potential to add premium transit in the
future, allowing a degree of flexibility to accommodate
changing transportation needs and priorities in the long term.
Source: Freedman Tung and Sasaki Urban Design, 2006.4
Awareness of these two concurrent efforts encouraged their integration, transforming the Highway 111 capacity planning project into a downtown/corridor revitalization project. This sought to address how capacity and multimodal mobility could be reconciled with downtown redevelopment objectives. The new downtown-friendly streetscape separates through movements on Palm Canyon from local travel, business access, pedestrian and bike travel, on-street parking, and transit stops. The boulevard-based streetscape design supports a broader plan for downtown revitalization, including a new City Hall, public safety building, cinema complex, town square, parking structure, and additional downtown retail development.
The project planning and design process resulted in Palm Canyon Drive as a four-lane, median-divided section, with local access streets divided from through lanes by raised medians. The design includes dedicated right- and left-turn pockets, restricted access to select cross streets, and signal timing and other traffic management practices. Few of these design techniques were conventional practice, and most were not permitted under Caltrans design standards. In partnership with the Riverside County Transportation Commission (RCTC), Caltrans agreed to relinquish the segment of Palm Canyon between Cathedral Canyon and Date Palm to the city, and in turn the city would ensure that the county's and Caltrans's traffic through-capacity targets would be met by the roadway design. The arrangement transferred county and Caltrans funds targeted for widening to the city project as long as traffic performance targets were achieved. The consulting team's innovative approach helped the city understand the traffic operations implications of the boulevard and develop recommendations for roadway design and traffic signal timing to preserve through-movement capacity on Palm Canyon.
Palm Canyon Drive's design sought to balance vehicle mobility needs of a transportation agency with
livability needs of the community. To achieve this balance, designers considered the supporting
street network and access to it from Palm Canyon.
Source: Freedman Tung Sasaki.5
The original multiway boulevard design concept emphasized a flexible approach based on a range of adjacent development types. Design features such as sidewalks, on-street parking, and transit facility location were chosen based on the land uses desired for different parts of the corridor. Roadway construction included a landscaped center median, two travel lanes in each direction, and an additional landscaped median separating a new angled parking and transit lane from the through lanes. Implementation involved elimination of numerous angular driveways that had compromised traffic operations, and pedestrian-oriented intersection improvements to better connect the two sides of the street.
Palm Canyon's reconstruction was completed in 1998, and several of the accompanying downtown projects have also been completed. These include the new IMAX theatre, City Hall, and several mixed-use retail and housing projects. The multiway boulevard has shown notable safety improvements, both for motorists and pedestrians. The city's traffic engineer noted after construction that the road, which averaged 3 pedestrian crashes per year in the mid-1990s, had not had any crashes reported.
Source: Freedman Tung and Sasaki Urban Design, 2006.6
Major roads through downtowns and aging suburban strips can be re-engineered in coordination with revitalization plans to improve through capacity, multimodal mobility, business and neighborhood access, environmental sustainability, and other community goals. By following multiway boulevard principles, understanding the context of individual blocks and surrounding development, and separating through travel from local access lanes, both capacity and multimodal choice can be improved.
Palm Canyon Drive also demonstrated the benefits of incorporating redevelopment plans with transportation plans, with interagency cooperation and combined funding yielding an innovative yet practical design. While early projects like this have had to either get design exceptions or required the State DOT turning over the road to local control, emerging design standards and more accepted practices should make it easier to replicate a similar approach elsewhere. The new manual, Designing Walkable Urban Thoroughfares: A Context Sensitive Approach, advances successful use of similar context-sensitive solutions in planning and design of major urban thoroughfares. The manual was developed by the Institute of Transportation Engineers (ITE) and the Congress for the New Urbanism (CNU), and sponsored by FHWA. It provides guidance on how context-sensitive design principles and techniques can be applied where community objectives support new urbanism and smart growth, walkable, connected neighborhoods, mixed land uses, and easy access for pedestrians and bicyclists.
The Riverfront Parkway was originally a four-lane
expressway with one signalized access point to
Source: Glatting Jackson Kercher Anglin, 2000.8
In many urban areas, past design decisions have produced a roadway that is incompatible with contemporary social and economic conditions, land use, and development context. Application of highway-oriented design standards in downtowns can leave roads overbuilt for current capacity needs, with speeds that are incompatible with urban areas. Transportation agencies are reluctant to relinquish system capacity and control, and allocation of scarce project resources to rebuilding a road with no capacity gain can be difficult to defend. As a result, overbuilt roads remain in urban areas, even when their traffic benefits are outweighed by the lost opportunities for community building.
In Chattanooga, TN, one such roadway provides a powerful example of how this seeming incompatibility was addressed. The conversion of Riverfront Parkway from a four-lane, limited- access expressway to an urban surface street played a key role in fulfilling a long-term vision for transformation of Chattanooga's downtown. It is also an example of how roadway function can change over time and how project design needs to address such a change.
For decades, Riverfront Parkway provided easy travel through the center of the city, primarily for freight traffic. The limited-access highway responded to needs of the 1960s and 1970s, but Chattanooga had changed as a community by 2000. An overall decline in industrial output and activity eliminated the previously forecast growth in truck traffic volumes. Several properties along the parkway were beginning to redevelop into commercial uses and civic destinations, adding population and visitors to parts of central Chattanooga that had been occupied by industrial uses. This shift in the city's economic geography left the parkway as the central spine of the waterfront, serving multiple visitor destinations. This highlighted the need to reconsider the road's balance of access and mobility, including improved access to and from downtown, since there was only one direct downtown access point. Travel lanes were divided by concrete barriers and flanked by guardrails and fences, designed for high-speed movement and truck traffic, and limited crossing by vehicles and pedestrians wanting to reach riverfront destinations.
Construction of Ross's Landing Park, the Tennessee Aquarium, and several other riverfront improvements emphasized the need to make the riverfront accessible to pedestrians from downtown, which was prevented by the limited-access nature of Riverfront Parkway. Since the parkway was a major link in and out of downtown Chattanooga, under control of the Tennessee Department of Transportation (TDOT), its ultimate design was not completely within the control of the City of Chattanooga.
The City of Chattanooga and RiverCity Partners, a private, not-for-profit organization, commissioned a consulting team to develop an integrated transportation-land use design for Riverfront Parkway. Downtown development efforts were predicated on east-west improvements to regional capacity that could be achieved by making the parkway more accessible from downtown, so the design focused on this as well as improving pedestrian and local vehicle trip access to riverfront destinations. This included identifying places where downtown access could be enhanced by adding intersections, leading to a new design for Riverfront Parkway that turned it into more of an urban surface street.
Recommended changes to Riverfront Parkway included the addition of access to downtown
Chattanooga through new at-grade intersections and, in some places, the reduction of roadway
width from four to two lanes. Designers made a case that the use of network preserved overall
system capacity but that the re-design of the Parkway restored riverfront access from downtown.
Source: Glatting Jackson Kercher Anglin, 2001.9
Three primary objectives guided the design:
The last point reflects the general understanding among city and community leaders that Riverfront Parkway's original design goals were based on a different economic role for the city and its downtown.
The project focused on converting Riverfront Parkway to an at-grade street with four added downtown intersections. A portion of the street was designed as a two-lane section with widened sidewalks and enhanced landscaping, with the remainder a four-lane, median-divided street with similar features.
Source: Glatting Jackson Kercher Anglin, 2001.10
The additional intersections were intended to improve traffic operations by distributing entering (westbound) traffic into downtown at more intersections, reducing pressure on the Riverfront/ Chestnut intersection at downtown's western end. This assumed that volumes would gradually decrease from east to west, as more traffic would use these new intersections to access downtown. The reduced volumes enabled a reduction in width to two lanes in the most critical areas of pedestrian travel, in front of the Tennessee Aquarium and Ross's Landing Park. Since pedestrian access from downtown to the riverfront was always seen as a key issue in Chattanooga's Vision 2000 goals, stakeholders in downtown planning and vision implementation agreed to pursue a more pedestrian-friendly cross section with midblock crossing access.
TDOT was not originally supportive of the city's vision and design proposal, and was not willing to advance the project despite ongoing efforts to find a workable solution. Chattanooga, with strong local leadership from then-Mayor Bob Corker, worked with State legislators and the Governor to have ownership and maintenance responsibility of the road transferred from the State to the city, effectively circumventing TDOT's opposition and allowing the city to proceed with construction. The completed Riverfront Parkway has improved downtown access, allowing more direct commuting patterns and renewing economic viability for the eastern portion of downtown. The project also realized Chattanooga's desired connection to the Tennessee River. Reduction of the roadway footprint created space for a pedestrian path connecting the Tennessee Aquarium with Ross's Landing, as well as access to public entertainment-oriented spaces stepping down to the river's edge.
Photo Credit: Glatting Jackson Kercher Anglin.
Source: City of Seattle, 2007.11
As with Palm Canyon Drive, the redesign of Riverfront Parkway was only achieved when the State DOT agreed to cede control of the road to the city. In this case, however, this was accomplished only when the Governor of Tennessee directed TDOT to relinquish control. This required strong leadership, but it also shifted the burden of funding entirely to the city. The city successfully met this challenge through a complex PPP and the dedication of revenue from a tax on lodging, and sees this project as helping to generate economic development benefits.
Highways like Riverfront Parkway are common in urban areas throughout the United States. As cities and towns strengthen their focus on quality of life and the economic development potential that it creates, adapting mobility-oriented infrastructure to a more flexible, multimodal design that supports community livability will become more accepted. The Riverfront Parkway design approach most easily reproduced is the use of an existing street network to assist in traffic distribution. Urban expressways were either built as new roadway alignments or as replacements of pre-existing streets, and intersections with local streets were closed or limited. The primary downtown access from Riverfront Parkway was focused at one signalized intersection, with expressway traffic shifting to local downtown traffic at a single point. By restoring an urban street grid with multiple access points, the new design was able to maintain through-traffic flow while improving vehicle and pedestrian access to downtown and the riverfront.
Roadway capacity and safety projects can be just as controversial in rural areas and small towns, typically in the form of either widening or bypass projects. Both approaches are seen by many residents and businesses as threatening community character and small-town economic vitality. Transportation agencies may understand this but are often bound by existing policies to preserve functional LOS along the road. U.S. Route 50 is one example of how a different approach to rural roadway improvements using a broader range of design tools preserved roadway function and performance within the context of a rural and small-town environment.
In the mid-1990s, VDOT began to discuss a potential bypass for U.S. Route 50 in Loudoun and Fauquier Counties around the towns of Middleburg and Aldie, as well as potential widening projects. Community residents opposed the concepts because of perceived impact on the corridor's character and the potential to invite further suburban development. However, they also understood the commuting patterns in the corridor and recognized the need to address the safety and congestion problems brought by increased traffic.
To address these issues, the Route 50 communities formed the Route 50 Corridor Coalition, and hired engineering consultants to develop a corridor traffic calming plan. The plan focused on maintaining the character of existing two-lane sections where possible, while improving capacity, safety, and multimodal connections in the small towns and hamlets. The plan introduced a more sophisticated array of design treatments to manage the motorist's transition from rural to town sections, and included using vernacular design materials and attention to contextual detail.
The VA Route 50 Traffic Calming Plan includes design context zones and transitions from rural highway to towns.
Source: Fauquier and Loudoun Counties, Virginia, 2003.12
Design tools included a transition from open shoulders to curb-and-gutter roadways, to slow traffic entering the towns. Within the town contexts, sidewalks, raised medians, and midblock pedestrian crossings helped raise motorist awareness of pedestrians and further slow traffic. In purely rural contexts, the wide shoulder was replaced with a stabilized turf shoulder that would support vehicles leaving the road but also provide a more aesthetic transition to the surrounding rural context. Roundabouts were used to address traffic congestion and safety at key intersections such as Route 50 and Route 15 at Gilberts Corner. The use of roundabouts prevented excess widening typically required for turn lanes at conventional intersections and improved traffic flow and safety while reducing speeds. Instead of focusing traffic movements on a single intersection, the Gilberts Corner design added three roundabouts: one at the primary intersection point of Routes 15 and 50, and two others connecting a new roadway between these roads that accommodated movements between the south and east directions.
The traffic calming plan was adopted by the Middleburg Town Council and the Loudoun and Fauquier County Board of Supervisors in 1997, and was recognized by the ITE President's Award for Excellence. The following year, Virginia Senator John Warner secured $13 million in congressional funding for the traffic calming demonstration project under the Federal TEA-21 transportation bill. In 2000, a second round of planning and design began with VDOT and the Route 50 Corridor Coalition working together in the Route 50 Traffic Calming Task Force. The Task Force is responsible for overseeing the plan's implementation as it goes through project development, final design, and construction. A design memorandum was produced in 2003, followed by full construction design documents. Project construction began in 2007, with various elements of the project completed and some underway.
Along VA Route 50, the Gilberts Corner roundabout
plan accommodates substantial turning movements
between Route 50 and Route 15 by adding a new
diagonal connecting road with additional roundabouts.
Source: Virginia DOT, 2008.13
Photo Credit: Ginny Finley, Vanasse Hangen Brustlin, Inc.
This was the first time that VDOT applied traffic calming to a primary State highway. On the scale of a 20-mile corridor, the project has faced complications from design exception processes, costs, and drainage. Implementation proved to be more complex and time- and resource-intensive than anticipated, which in turn delayed the overall project implementation schedule. Many of the conceptual design tools were not typically used in VDOT's roadway design projects, and proved challenging during design development. Challenges to constructability of some initial concepts might have benefited from greater design expertise. Several design concepts were not allowed by VDOT standards. These had to go through the design exception process for approval, requiring approval above the district VDOT office responsible for project management and construction (adding significant delay). Route 50's location in a mostly rural area limited availability of alternative detour routes, leading to added costs for maintenance of traffic operations.
Through anecdotal accounts, the new design has significantly altered the behavior of drivers along the Upperville portion of Route 50, and at Gilberts Corner, the intersection of Routes 50 and 15 and historically the source of greatest travel delay along the 50 corridor. Fewer cases of acute congestion are observed at the new roundabouts at Gilberts Corner compared to the previous signalized intersection (at this writing, VDOT planned to conduct more formal studies to measure the effect of the traffic calming measures).
Positive outcomes have also occurred in the form of structural and institutional change, though this has not yet occurred on a scale to enable such a project without special review. VDOT has adopted the AASHTO Policy on Geometric Design of Highways and Streets as its standard design guidance, and has created a process where projects not compliant with VDOT standards but falling within AASHTO's suggested parameters can qualify for a design waiver at the district office level (and thus do not have to seek a formal design exception from the chief engineer at the central VDOT office).
Another challenge that agencies face is incorporating facilities for walking and wheeling on major highways functionally designated and designed primarily for automobile and truck use. The Woodrow Wilson Bridge carrying I-95 and I-495 (the Capital Beltway) over the Potomac River south of Washington, DC, is one example of how multimodal project planning can be incorporated into large-scale highway facilities. Interstates and other limited-access, high-speed roadways are not typically focused on accommodating multimodal, nonmotorized use. An increase in regional demand for walking and biking, combined with limited Potomac River crossings, underscored a unique opportunity to pursue these improvements in reconstruction of the bridge.
Initially designed to carry 75,000 vehicles per day, the old bridge had traffic volumes of 195,000 vehicles per day by 2004. Consequently, heavy traffic congestion and major delays became daily occurrences, leading to regional demands for a new and larger bridge. Excessive traffic loading also took a toll, accelerating deterioration and raising safety concerns. As planning for redesign and reconstruction of the bridge began, stakeholders expressed a need for this critical connection-the only Potomac crossing south of downtown Washington within the metropolitan area-to include potential carrying capacity for expanded transit and nonmotorized travel.
When planning for the bridge began in the late 1980s, FHWA maintained the following four objectives for the project:
With these in mind, design focused on increasing vehicle capacity as well as providing a separate envelope for walking and wheeling. Significant challenges existed, such as negotiating complex agreements between VDOT, MDOT, and FHWA; lawsuits filed by condo owners; and opposition from the City of Alexandria. MDOT and its State Highway Administration sponsored a design competition that led to several ideas ultimately integrated into project design. After a series of revisions from a contentious environmental review and NEPA compliance process, with four separate review panels to ensure that the design fit appropriately within its environmental context, FHWA finalized the bridge design in late 1999. This included 12 lanes of vehicular traffic with a separate bicycle-pedestrian trail component on the northern side of the bridge span connecting to the Mount Vernon Trail in Virginia and Potomac Heritage Trail in Maryland. The 12 vehicular lanes are configured with 6 per direction: 3 per direction used for local traffic, 2 per direction for express traffic, and 1 per direction for HOV and bus traffic.
The new bridge opened to traffic in 2006, with the bicycle and pedestrian path on the northern side of the bridge span opening in 2009. The trail design also included bridge crossings over the vehicle lanes at each end, so pedestrians and bicyclists can safely cross the bridge.
Although the bridge itself provides excellent multimodal facilities and connects to trails on both sides, bicycle advocacy groups have been critical about the limited bicycle network on the Maryland side. This highlights the need to implement complete streets and networks approaches in all projects, so that users of all modes can access the same destinations. Although there are no current plans for such facilities, the width and load-bearing capacity of the bridge were designed to accommodate future heavy rail transit.
In many ways, design-based approaches begin to emerge when a transportation agency has already embraced livability concepts, and learned through visioning, planning, and policy how best to apply them at the institutional level. The case studies demonstrate that certain design tools and techniques can carry this agency commitment to the project level. In some cases, such as Hillsborough Street, transportation agencies have been proactive partners with the communities they serve, expanding their thinking beyond conventional highway planning to understand the benefits of a livability approach. These cases demonstrate the benefits and necessity of designing transportation projects with livability in mind, understanding that the design stage is where many of the human-scale factors of livability are incorporated.
Many early creative projects were not done within the typical institutional parameters of transportation agencies. Their supporters sidestepped agency-based limitations, either by removing a project from the State agency's purview or involving other political leaders. These case studies did not proceed through a conventional, transportation agency-led project development process, but were initiated through community interest in promoting livability.