Route change on the American freeway system

Journal of Transport Geography 67 (2018) 12–23

Contents lists available at ScienceDirect

Journal of Transport Geography journal homepage: www.elsevier.com/locate/jtrangeo

Route change on the American freeway system

T

Joe Weber Department of Geography, University of Alabama, 202 Farrah Hall, Box 870322, Tuscaloosa, AL 35487, United States

A R T I C L E I N F O

A B S T R A C T

Keywords: Freeway Interstate highway system Route change Networks

The first elements of the American freeway system were built in the 1920s and now comprise over 59,000 miles of roads. In addition to growth in the system at both the national and urban levels and increases in capacity, over five hundred miles of freeways have been relocated. These route changes have previously escaped attention from researchers. A database of all route changes on the Interstate system and other freeways was compiled in GIS and analyzed. Route changes are due to the need to replace old and obsolete bridges and tunnels, rebuild sharp curves or steep grades, and eliminate substandard sections. These route changes are overwhelmingly urban in nature. New relocations will appear as the American freeway system ages and continues to adapt to changing conditions. Some bypassed sections of freeways may eventually become tourist attractions.

1. Introduction Before World War Two a number of cities had begun planning and building parkways, expressway, or freeway systems. New York initiated the largest system in 1923 with the world's first freeway, the Bronx River Parkway. This was a 20 mile multilane road with 28 overpasses as well as 35 miles of walking trails and 60,000 trees or shrubs (MacDonald, 2002). Los Angeles opened the Arroyo Seco Parkway in 1940, the first of many freeways in that city. Elsewhere isolated roads appeared, including the Merritt Parkway in Connecticut in 1938 and the Pennsylvania Turnpike between Carlisle (west of Harrisburg) and Irwin (east of Pittsburgh) in 1940. These early freeways were incorporated into a nationwide freeway system that began construction in the postwar era. This new Interstate Highway System was actually initiated in the 1930s and formally created in 1944, but little was accomplished until it was put on a secure financial foundation in 1956. The system had its origin as a set of longdistance routes connecting the nation's largest cities. An extensive set of urban routes was added later to facilitate passage through cities and gain the required favor of urban congressmen, though at enormous cost in economic and social disruptions of established neighborhoods (Schwartz, 1976; Seely, 1987; Rose and Mohl, 2012). The system continues to have tremendous impacts (often unanticipated) on the nation's mobility, accessibility, economy, and urban geography (Garrison, 1960; Moon, 1994; Weber, 2004, 2011; DiMento and Ellis, 2013). It has been expanded from 40,000 miles in the original plans to almost 47,000 miles in 2017, along with another 12,000 miles of non-Interstate freeways to make up an American freeway system of over 59,000 miles (Weber, 2012, 2017).

But freeway routes were not always built according to plan. Over 340 miles of planned Interstate routes were altered or cancelled before construction (Weingroff, 2015a), along with a substantial mileage of other freeways, much of it attributable to various ‘freeway revolts’ from the 1950s into the early 1970s (for example, Baumbach and Borah, 1981; Rodriguez, 1999; Mohl, 2004, 2008; Rose and Mohl, 2012; DiMento and Ellis, 2013). These came about due to local opposition to freeways being built through established neighborhoods and the wholesale demolition of homes and businesses required. In some cases, notably in San Francisco or Memphis, these successfully prevented the construction of new freeways or forced redesigns of others. Although one of the most substantial and expensive components of contemporary transport systems, freeways are not permanent and unchanging. In addition to continual maintenance, reconstruction, and frequent widening, freeway routes may be altered, as when sharp bends are replaced with wider sweeping curves. These represent adaptations to changing standards or traffic, in which a highway route is altered to better fit current needs. This is a common occurrence with roads (Newton Jr, 1970, 1971; Clay, 1973; Raitz, 1996; Krim and Wood, 2005), but has gone unexamined in the case of freeways. This paper examines the phenomenon of route changes on the American freeway system in order to identify to what extent this system has evolved, why it has done so, and how it will likely do so in the future. After locating and mapping freeway route changes several specific questions will be addressed. How common have route changes been on freeways? What explains these route changes? And where and why will they take place in the future?

E-mail address: [email protected]. https://doi.org/10.1016/j.jtrangeo.2018.01.003 Received 20 July 2017; Received in revised form 18 December 2017; Accepted 15 January 2018 0966-6923/ © 2018 Elsevier Ltd. All rights reserved.

Journal of Transport Geography 67 (2018) 12–23

J. Weber

2. Literature review

place in the era of environmental impact statements and was built not just to higher standards but with environmental features in mind. Later generations differed in their funding and political justification; it is evident they also introduced improved landscaping and safety features as well as carpooling lanes and other features. Many of the features of later generations were retrofitted onto existing freeways, and along with widening to increase capacity and the need to replace worn out bridges, has meant not only that freeway construction has never ended, but never will so long as the system remains in use. There is every reason to expect that the system will continue to adjust. This situation is however complicated by politics. The Association for State Highway and Transportation Officials (AASHTO) Committee on U.S. Route Numbering is responsible for approving all changes to U.S. numbered and Interstate routes, which encompass most freeways in the U.S., using categories of establishment, elimination, extension, and relocation (AASHTO, 2017). Elimination refers to the removal of a particular route number, as happened when the legendary U.S. 66 was decommissioned in 1985. Extension is the lengthening of a route past its original endpoint, as when an extension of I-40 from Greensboro to Wilmington, North Carolina, was approved in 1984. Truncation would be the opposite, when a route is shortened from its original endpoint, as in 2011 when the eastern end of I-370 in Maryland was shifted west by one mile. With relocation a route number is moved from one road to another, which requires a distinction between the physical road and the numbered route. A road (and the route it carries) may be shifted to a new location and the old road demolished, or a route may be transferred to a new road while the old road remains in use with a different route number. Although all four cases can be found on the American freeway system, this paper focuses only on relocation. The goal is to examine these route changes in order to understand this important component of how the system has evolved and will likely do so in the future. Several questions will be addressed. How common have route changes been on the American freeway system? What explains these route changes? And where will they take place in the future?

Examining the growth of transport networks has long been a topic for geographers and others (Meinig, 1962; Thomas, 1963; Vance Jr., 1995; Xie and Levinson, 2009). One of the basic problems in network expansion is that of the location of individual routes (Vance Jr, 1961). This has usually been approached in geography as an optimization problem, typically that of minimizing travel time, construction cost, or some other variable. One of the earliest examples is that of Wellington, a railroad engineer seeking the most efficient route for trains (Wellington, 1893; Black, 1993, 2003). His approach balanced operating costs with the potential to increase revenue by adding more towns to a rail line. A related concept is the law of refraction (Warntz, 1957; Werner, 1968), in which an optimal route is found across several cost surfaces. This approach is now more likely to be expressed as costdistance models within GIS that finds a route across a raster surface with cells coded for cost, effort, or other variables (such as Atkinson et al., 2005; Howey, 2007). Each optimal route would be based on particular factors involving terrain, vegetation, water, land ownership, or other relevant considerations. This has found application for route location problems (Atkinson et al., 2005) as well as predicting or explaining historic or prehistoric routes (Howey, 2007; Raitz et al., 2010). Route changes can be conceptualized as being due to changes in the optimal route location due to some external event or changing conditions, or the need and ability to further reduce travel time or cost, perhaps as speeds and traffic volumes increase. The standards to which highways have been built have changed continually to the present, including preferred and maximum grades up and down hills, curve radius, sight distance, lane width and road capacity, and the design speed of the road. Preferred values for road curvature, measured as the radius of a circle that fits the road's curvature, increased from 100 ft in the 1850s (Gillespie, 1853) to 200 ft at the beginning of the automobile era (Harger and Bonney, 1912), and between 1000 and 5000 ft by the 1930s (Wiley, 1935; Bruce, 1937; Hewes, 1942). Other design features were added, such as superelevated or banked curves and a spiral transition into and out of curves. While some improvements can be incorporated within a road's right of way, changes involving curves or gradients will often require a new location to contain these improvements. Descriptive route change models incorporating these changing features have been devised showing how roads change over time as they are improved and the roadside environment is developed (Clay, 1973; Clay and Raitz, 1996). Despite tremendous attention given to highway evolution, freeway route change has received none, perhaps because freeways are treated as the end of highway evolution. Descriptive models of American highway evolution have treated freeways as a final stage of development. As part of his historical geography of American transportation James Vance Jr. (1990) described five broad stages in the development of the American highway system, for which the fifth and last stage began in 1956 when the Interstate Highway System was fully funded and construction began in earnest, creating a national system of freeways. Similarly, Hokanson (1988) described four stages of highway construction for which the fourth and last stage is the Interstate Highway System and similar freeways. In these accounts the beginning of the Interstate system in 1956 marks the end of road development. But 1956 was not the end of the road. Design standards for this system have evolved tremendously over time, and the American freeway system has been continually changed to keep up with new conditions. Weiss (2008) identified a number of distinct Interstate ‘generations,’ beginning with early freeways built before the Interstate Highway System was fully funded. ‘Interstate 1.0’ began in 1956 and rapidly built routes with narrow medians and the possibility of left hand exits. This system also incorporated many existing freeway routes built to lower standards than are found now. An ‘Interstate 1.1’ began in the 1960s with improved ramps and wider medians. ‘Interstate 2.0’ took

3. Data and methods There is no database of highway route changes to draw on. Federal Highway Administration statistics (FHA, 2016) show the mileage, lane miles, vehicle miles traveled (VMT), cost, pavement condition, and other variables by state and for the nation, but are not broken down by route. Instead, freeway route changes were found by examining the entire freeway system for evidence of change. First, aerial imagery of all freeway mileage in the contiguous 48 states were examined for recent location changes in Google Earth software (Google, 2017). Changes in major cities were found comparing current and older aerial imagery, allowing changes within the past 10 to 15 years to be found. A search of the entire freeway system was carried out using a United States Geological Survey 7.5 min topographic map overlay (USGS, 2017). These 1:24,000 scale maps typically date from the 1970s and 1980s and show roads with a high level of locational accuracy. When displayed in Google Earth with the software's current road overlay they will reveal any changes since the maps were made. Recent route changes were also found by examining the meeting reports of the Association for State Highway and Transportation Officials Committee on U.S. Route Numbering (AASHTO, 2017), which has jurisdiction over numbering for the majority of freeways in the country. A list of decisions made onwards from 1989 is available on their website. Finally, histories of a few older highways, such as the Pennsylvania Turnpike, are available (for example, Cupper, 1990), and these sources provided details on some of the earliest route changes. While not a comprehensive list of all freeway route changes, it is expected that the majority of significant changes have been found. A GIS database of these route changes was created in ArcGIS (ESRI, 2017) by mapping route changes as linear features, though in Fig. 1 these are 13

Journal of Transport Geography 67 (2018) 12–23

J. Weber

Fig. 1. Freeway route changes.

shown as points for clarity. Approximate mileages were measured and represent the length of the road bypassed; these may differ from official project length listed in planning documents. As noted earlier this paper focuses on relocation rather than extension or truncation, which were not included here. Neither were freeway routes cancelled or changed before construction (as during a freeway revolt). Some freeway route changes were temporary and were not included in the table, as when I95 in Wilmington, Delaware, was realigned onto I-495 from 1978 to 1980 while the original route was reconstructed. Nor were uncompleted freeways, such as a 0.65 mile extension of I-189 in Burlington, Vermont, that never opened.

Table 1 Summary of route changes by type and fate. Freeway route changes by category Category

Number

Total length (miles)

Average length (miles)

Interchange New bridge Tunnel bypass Curves and Hills Relocation Abandoned Total

20 28 3 16 39 8 114

25.11 52.07 16.09 18.21 437.73 11.42 563.43

1.26 1.86 5.36 1.14 11.22 1.78 4.94

4. Results Freeway route changes by fate of roadway

Over 110 instances of freeway route change were identified (Fig. 1, Appendix A). They are scattered throughout the country and total about 563 miles, or 0.95% of the total length of the 59,563 mile American freeway system. Although relatively small, this mileage is substantially greater than the 340 miles of Interstates cancelled or changed because of freeway revolts (Weingroff, 2015a). It is evident that route changes fall into several basic categories, including the rebuilding of bad curves and/or steep hills, replacing aging bridges or tunnels, moving freeways away from airports or other sensitive sites, or simply moving an established numbered route to a different existing road (Table 1). Not surprisingly, only in a few cases were freeways demolished or abandoned without replacement. All instances of route change were classified as to type, category, and fate of the bypassed section using these categories. Although the Interstate System was built to the highest standards of the time it often incorporated existing roads with sharp curves and steep hills. Improving these has led to several relocations totaling over 18 miles (Fig. 2). Examples of these include a 2.95 mile long stretch of I44 about 9.5 miles west of Rolla, Missouri. The original route had five sharp turns required because the freeway followed a curving ridgeline.

Fate

Number

Total length (miles)

Average length (miles)

Demolished Abandoned In use as street In use as freeway Research Center Total

75 7 9 22 1 114

115.7 20.84 18.36 407.4 1.13 563.43

1.54 2.98 2.04 18.52 1.13 4.94

This was reduced to two gradual turns in 2002, though the new route required deep cuts and high fills to maintain a constant grade. In Arizona a four lane highway was incorporated into I-10; the highway had once crossed over a railroad on an S-curve. The railroad had long been abandoned and the overpass demolished, but the curve remained on the freeway until it was straightened in 2012. A railroad crossing in Laurel, Mississippi required an S-curve on I-59 that was straightened in 2009. The relocation required the demolition of twenty houses but opened up several blocks for redevelopment adjacent to downtown (which remain vacant). 14

Journal of Transport Geography 67 (2018) 12–23

J. Weber

Fig. 2. Selected freeway route changes involving curves and hills.

Several route changes replaced aging elevated freeways, as with I40 in Oklahoma City, in which a 1.7 mile elevated road near downtown was replaced in 2012 by a new route almost half a mile to the south. The replacement of the elevated route of I-93 in Boston with a tunnel in the Big Dig project is similar, as well as being a less common example of vertical relocation of a freeway route. Although not as frequent, 16 miles of relocations have come about when old tunnels have been bypassed by open cuts. This again could be due to functional or structural deficiencies. This has occurred at two locations on the Pennsylvania Turnpike and one on the West Virginia Turnpikes, though the new routes are necessarily located farther from the old road than for most bridge replacements. The reconstruction of major urban freeway interchanges frequently results in minor realignments, amounting to 25 miles of relocated highway systemwide. This is particularly the case with early interchanges where lanes diverged to allow for left-hand exits and onramps, as at the Big I interchange between I-40 and I-25 in Albuquerque. The rebuilt interchanges straightened the minor curves required in the highway for these ramps. The expansion of airports has led to relocated freeways in Atlanta, Indianapolis, Tampa, and Greensboro (Fig. 3). In all cases freeways passing the airport or providing access to it were relocated farther away to allow for new runways or terminals. The Atlanta relocation was required due to the construction of the current airport terminal, while two Greensboro relocations occurred for the construction of a second runway. Interestingly, in Atlanta and Las Vegas freeways have been built underneath runways (or vice versa) during expansions, but in these cases the freeway crossings are at less acute angles. Airports are among the few land uses that take priority over a freeway. Another, in Arlington, Virginia, is the Pentagon building, as half a mile of Virginia Route 110 was moved about 390 ft east in 2004 to increase the distance vehicles could approach the building in a post-9/11 security climate.

Over 50 miles of freeway relocations stems from the replacement of large bridges, either due to functional deficiencies (too little capacity for traffic levels) or structural deficiencies (structural problems requiring the bridge be replaced before it collapses). Smaller bridges can be replaced with the use of temporary detours, but for very long bridges there may be no possibility for this. In these cases a new bridge is built next to the existing one and the freeway realigned to cross over this new bridge when it is completed. The old bridge is then usually removed, leaving no trace of its former existence except for a slight curve in the freeway approaches. The shortest of the bridges whose replacement required a route change was about 700 ft, but most were over 1000 ft in length. The replacement of the 1951 Pennsylvania Turnpike bridge (about 2180 ft in length) over the Allegheny River in 2009 is a good example. Replacements for long I-10 bridges in Louisiana and Florida severely damaged by hurricanes are further examples. Not all major bridge replacements led to route changes; if a bridge collapses the route must be closed while a new bridge is built on the same location. For that reason the new bridges built for I-40 at Webber Falls, Oklahoma, which collapsed in 2002, and for I-35W in Minneapolis after its collapse in 2007, do not show up on the map. The 1987 replacement of a drawbridge on I-75 in Saginaw, Michigan, by a taller bridge allowing greater shipping clearance (Hyde, 1993) highlights a special class of substandard bridges on the Interstate System. At least 16 more drawbridges remain on the Interstate System, most built before the system and grandfathered into the network. The oldest of these is the 1917 bridge carrying the northbound lanes of I-5 over the Columbia River between Oregon and Washington. Replacing these bridges with higher bridges would improve traffic flow by preventing occasional freeway closures, but the 2008 Woodrow Wilson bridge on I-95 over the Potomac River (the Washington Beltway) still includes a drawbridge. This new bridge is higher and the drawbridge is expected be opened many fewer times per year (Kozel, 2016).

15

Journal of Transport Geography 67 (2018) 12–23

J. Weber

Fig. 3. Selected freeway route changes involving airports and the Pentagon.

Fig. 4. Selected freeway route changes involving relocations.

16

Journal of Transport Geography 67 (2018) 12–23

J. Weber

This change introduced several sharper curves into what had been a gently curving roadway. In all of these cases both routes and roads are changed, and the old road is usually demolished. However, the greatest mileage of route change has come about when the route is changed but the road is not. In these cases, rather than upgrade a substandard road to modern standards the route number is transferred to a newer, higher quality road and the old road remains a substandard freeway with non-Interstate numbering. Over 437 miles of freeways were shifted in this way. This includes I-80 in Sacramento, I-40 in Winston-Salem, and I-85 in Spartanburg (Fig. 4). I-80 originally ran through central Sacramento on freeways constructed as early as 1947 and well below Interstate standards (Faigin, 2010). In 1972 I-880 was completed as a bypass around the city to the north. After plans to rebuild the substandard route of I-80 were abandoned the highway was relocated to the newer I-880 in 1983. The old route of I-80 remains in use as U.S. 50 and Business I-80. The original route of I-40 through Winston-Salem, North Carolina, was built in the 1950s and 1960s and incorporated freeways built before the Interstate System started (Weingroff, 2015b). With increasing traffic volumes the road soon became inadequate. In 1992 a new I-40 was built several miles to the south. The old freeway was redesignated Business I40, as its substandard condition did not allow it be renumbered as a 3digit Interstate loop route (Business routes are not considered Interstate routes). The Hawthorne Curve, a dangerously sharp curve located along Business I-40, was straightened later. A similar story exists for I-85 in Spartanburg, South Carolina, where the original 1959 freeway was considered substandard (Weingroff, 2015b). Rather than improve it a new freeway was built to the west in 1995 and I-85 shifted onto this road. The old freeway remains in use as Business 85. Another category of freeway route changes, totaling 14.22 miles, is that when freeways were closed, abandoned or even demolished without a replacement freeway being constructed. This can be dated to the abandonment of the Long Island Motor Parkway in 1938 (Kroplick and Velocchi, 2009). This 45 mile route, opened in 1908, was one of the first limited-access highways, though it lacked features that would define it as a freeway by contemporary standards and it is not included here. The demolition of the Embarcadero Freeway in San Francisco in 1991 is probably the best known case of freeway abandonment without replacement. This 1959 elevated freeway was closed after suffering damage in the 1989 Loma Prieta earthquake and never reopened; city leaders sought to use the opportunity to fulfill a long time goal of removing it and were ultimately successful (Rodriguez, 1999). Another example is the demolition of the elevated West Side Highway in Manhattan. This opened in 1951 but suffered a partial collapse in 1973 that led to its closure and eventual demolition in 1989. A subset of abandoned routes is short sections of road that were intended to be freeways but never completed as such. The Red Skelton bridge over the Wabash River at Vincennes, Indiana, was built to become part of I-64 between St. Louis and Louisville, but after lobbying by residents of southern Indiana it was decided to build this route farther south (Ripple, 1975). The orphaned bridge was completed as part of U.S. 50 and is now part of the Vincennes bypass. Another orphaned freeway was built as part of I-310 through the French Quarter in New Orleans. This was a short depressed roadway completed in 1966 near the foot of Canal Street (Baumbach and Borah, 1981). This section of former freeway now serves as a parking garage underneath Harrah's Casino.

Table 2 Summary of route changes by location. Freeway route changes by category Category

Urban Number

Suburban

Length

Number

(miles) Interchange New bridge Tunnel bypass Curves and Hills Relocation Abandoned Total

20 13 0 7 33 7 80

25.11 20.35 0 5.93 371.2 12.22 434.81

Length

Rural Number

(miles) 5 4 0 3 9 1 22

6.71 7.43 0 3.51 136.24 1.4 155.29

Length (miles)

0 12 3 8 3 1 27

0 26.99 16.09 11.21 7.84 2.0 64.13

Freeway route changes by fate of roadway Fate

Urban Number

Length

Suburban Number

(miles) Demolished Abandoned In use as street In use as freeway Research Center Total

52 2 6 20 0 80

75.03 1.25 9.93 348.6 0 434.81

Length

Rural Number

(miles) 14 2 2 4 0 22

21.52 3.69 3.05 127.03 0 155.29

Length (miles)

21 3 1 1 1 27

40.26 15.9 3.04 3.8 1.13 64.13

Winston-Salem area have noteworthy collections of route changes, while the San Francisco and Jacksonville areas have a number of shorter relocations (Fig. 1). The Pennsylvania Turnpike, the first major rural freeway in the country, is one of the densest concentration of changes. None are apparent in the northern Rockies and northern Great Plains, and it appears that the pattern broadly reflects population and road mileage. Freeway route changes are overwhelmingly urban (Table 2). Almost 435 miles (77.2% of the total mileage) is within urban areas, a much higher value than for the total freeway system, for which only 62% of mileage is within metropolitan areas and 32% of total miles lie in urbanized areas. This can be explained not only by the heavy traffic of urban freeways, and consequent need to continually upgrade roadways, but also because it was in cities that many early freeway routes were built; this is therefore where improved standards would most likely require a route change. Route changes show a number of patterns by location. None of the three tunnel replacements were found in urban areas, though many of the Interstate's tunnels are urban. Not surprisingly, route changes stemming from new interchanges were common in cities but not present in rural areas. However, route changes as a result of rebuilding sharp curves and steep hills are almost evenly distributed between urban areas and rural, though those in rural areas account for twice the mileage. Relocations are overwhelmingly urban in number and more so in mileage, and almost all abandoned freeways are urban. It is also evident that a wider range of outcomes exist in urban areas than rural. The outcome of converting a freeway to a street or simply renumbering it is rarely an option in rural areas but more common in cities. Just over 155 miles lie within suburban areas (27.6% of the total mileage), and the distribution of route changes is similar to urban areas though smaller in number and mileage. It is likely that these will increase as beltways and other peripheral routes age. Have route changes become more frequent as the freeway system has aged? The number of route changes has generally increased over

5. Discussion Several questions can be asked about these route changes and abandonment, beginning with their geographic distribution. They are most common in California, the Midwest, and rapidly growing areas in the South and Arizona. Tampa-St. Petersburg and the Greensboro/

17

Journal of Transport Geography 67 (2018) 12–23

J. Weber

Fig. 5. Freeway route changes by year.

most dramatic examples of freeway route change are the 20 miles of freeways that were demolished or abandoned without replacement by new ones. San Francisco's Embarcadero freeway is one of the best known examples of these. A final question is whether freeway route change can be explained by traditional notions of route optimization. Straightening curves and flattening hills and some relocations match the approach to route optimization used by cost-distance models, but relocations and route changes caused by capacity improvements (tunnel bypasses, interchange replacement, and many bridge replacements) should also be thought of as route optimization by improving travel times. This is not to say that most freeways are already in optimal locations, and the cost of relocation is obviously a significant barrier to making changes. Land value is one such barrier, shown by the fact that major airports and the Pentagon are among the few land uses capable of taking priority over freeways. Rising land values, in part due to previous freeway construction, has been given credit for substantially slowing California's freeway building boom of the 1960s (Taylor, 1995, 2000). As cities adapt to freeways it becomes more difficult to adapt freeways to changing urban environments. Unlike the construction of these roads none of these route changes appears to have been accompanied by any kind of freeway revolt, though at least a few homes were demolished for some. To the contrary, the public appears to be in favor of at least some changes, as when unpopular elevated freeways were removed (Rodriguez, 1999). The driving public is undoubtedly unaware of the vast majority of these changes.

Fig. 6. Former I-85 in Spartanburg, South Carolina. Source: Author.

time until the beginning of the 2007–2009 recession, at which point highway work has been scaled back (Fig. 5). This clearly shows that more changes have been necessary as the freeway system ages, and also that economic conditions strongly affect the ability to make these changes. The number of changes has not yet rebounded even as economic conditions have improved, indicating either that transportation projects have not yet fully resumed or priorities have shifted. The actual mileage relocated every year does not show this increasing pattern as it is overwhelmed by the 77.5 mile relocation of I-20 in Dallas in 1972 and 55 mile relocation of I-15 in California in 1982. What happens to the sections of road that were replaced? The vast majority of mileage is still in use as freeways, due to relocation of the route but not the road. So while 115 miles of freeway have been demolished, in the majority of cases this was due to the road being relocated (Table 1). Just over 18 miles of freeways have been converted to or replaced by streets. California Route 275 on the west side of Sacramento and Arizona Highway 153 (the Sky Harbor Expressway) in Phoenix (completed in 1996) were both converted to streets in 2007. A short section of the former northbound lanes of I-85 in Spartanburg remain drivable as a local street (Fig. 6). Former freeways can also be converted to other uses; a tunnel on the West Virginia Turnpike (I-77) bypassed in 1987 is now the Center for National Response, a training facility for fire fighting, disaster response, and anti-terrorism training, even featuring a replica subway station (CNR, 2017). The Sunshine Skyway bridge in Tampa (I-275) is paralleled by fishing piers that are the remnants of old I-75, destroyed by a ship collision in 1980. The

6. Conclusions While it is sometimes disparagingly noted that the Interstate System is over 70 years old and therefore out of date in an age that increasingly values multimodal and nonmechanized transport, the reality is quite different. The system has been continuously upgraded and refurbished, with many new environmental and safety features added and construction required to address challenging social issues (Weiss, 2008). It continues to carry a tremendous amount of the nation's motor vehicle traffic (FHA, 2016) and will continue to do so for the foreseeable future. It will continue to grow, and basic links such as I-95 between Philadelphia and the New Jersey Turnpike have not even been completed yet (Frassinelli, 2010). Understanding changes to the Interstate system is important because these events will continue in the future, and at predictable

18

Journal of Transport Geography 67 (2018) 12–23

J. Weber

Fig. 7. Potential future freeway route changes.

time, but there still exist 283 miles of freeway with 6% or steeper grades, often requiring runaway truck ramps (R&R Publishing, 1997, 2006). Of this mileage 29% is in the Appalachian Mountains, including the longest stretch of steep road found anywhere on the American freeway system. It is in this region that freeways were first built through mountainous terrain, and it should be no surprise that this area includes many tunnels, deep cuts, and steep grades that do not meet modern standards. With the exception of the Woodrow Wilson bridge on the Washington Beltway all freeways in the United States are controlled at the state or local level; while the narrative of the freeway revolt often juxtaposed federal engineers against neighborhoods this was never the case. State highway departments did have tremendous powers, but during the period of the revolt these were tempered by the requirement of involving local governments and citizens in planning (Mohl, 2004, 2012). The revolt also resulted in the cancellation of many planned projects, and at least several of the urban route changes identified here were due to these efforts, most notably in Memphis and San Francisco. Considerable effort since that era has been made by planners seeking to better integrate freeways into the urban environment and repair damage done to cities by their construction (Rapuano et al., 1968; Hestermann et al., 1993; Rose and Mohl, 2012; DiMento and Ellis, 2013). More recently this has produced the ‘tear down movement’, which seeks to replace obsolete or worn out freeways with landscaped streets, busways, or even parks rather than new freeways (Mohl, 2012; DiMento and Ellis, 2013). The need to replace an elevated stretch of I81 in downtown Syracuse is one project that has drawn attention from this movement, often using the case of Harbor Drive in Portland and the Embarcadero Freeway in San Francisco as examples of how freeway removals can work. If this movement becomes more influential there will be substantial impacts to the number and location of urban freeways; the freeway changes identified here could become paradigmatic

locations. A number of potential changes known to the author are shown in Fig. 7; these are all situations in which plans have been developed. This map is highly speculative, but there are a number of generalizations that can be made as to where and why freeway route changes will occur. Replacing bridges, tunnels, and interchanges can be thought of as a routine activity that will always need to be done. Some of these replacements will result in route change, and the number of these changes should increase over time as the Interstate system ages. Among the leading candidates are the 2726 bridges on Interstate routes over 1000 ft in length and built before 1956 (three of which are over one hundred years old). Among these are the twin I-5 spans over the Columbia River in Portland, Oregon. The first of these was built in 1917 (and once carried streetcars) and the second in 1958. Both have lift spans to allow ships to pass. Planning to replace these has begun but has been very limited due to an absence of funding. The 1963 I-71/I-75 bridge over the Ohio River at Cincinnati needs replacement, again suffering from an absence of funding. These large bridges will have to be replaced with bridges built on new locations to maintain traffic flow. There are also at least 36 remaining highway tunnels on the Interstate System running a total of 29 route miles, dating back to 1939 (Abramson, 2006). These too will all eventually need to be replaced. Plans have started to bypass the oldest of these, the Allegheny Tunnels on the Pennsylvania Turnpike (Malawskey, 2015). Elevated highways have fallen out of favor, and a number of these structures from the 1950s have already been replaced or abandoned, and this will continue (Mohl, 2012). The 1953 Alaskan Way viaduct in Seattle is nearing the end of its life, with a replacement tunnel under construction. Like the Big Dig, it will be a vertical relocation. Route changes for substandard grades or curves would presumably only need to be carried out once and the number of these substandard freeway sections left to replace would be expected to decrease over

19

Journal of Transport Geography 67 (2018) 12–23

J. Weber

in the field of planning for decades to come. Understanding these examples, and why and when they were possible (as well as instances when relocation or abandonment was rejected) would be crucial. Freeway relocations are dependent on funding, and the effects of the recession are still apparent in a much reduced rate of change (Fig. 5). Should financial conditions improve changes to the freeway system can be expected to increase. Construction of a new freeway to reroute I-85 around Montgomery, Alabama started in 2006 before being suspended (Shryock, 2011). Construction resumed several years later and the first section only opened in 2016; completion of the project is likely a decade in the future. Funding limitations in the near term may however increase the likelihood of changes being required later in the century. In the 1970s expansion of the Interstate system was allowed by the addition of ‘nonchargeable’ routes, which are those signed as Interstates but with greatly reduced federal funding. A number of future routes have been added to the system this way since the 1990s (FHA, 2008), among them I-11 between Las Vegas and Phoenix, I-69 between Indianapolis and Mexico, and I-73 and 74 between the Midwest and South Carolina. As funding is limited many sections of these roads have been completed by incorporating older freeways and upgrading existing four lane highways. If construction continues on these new routes they could introduce additional substandard mileage into the American freeway system, requiring future relocations. The incorporation of early freeways into the Interstate system in the middle of the twentieth century, the source of many later necessary changes, may therefore be repeated in the middle of the twenty-first. There are also long term environmental changes that may hasten freeway relocations. Several route changes along I-10 came about because long bridges were destroyed by recent hurricanes. This can be expected to recur, and the effects of coastal flooding from sea level rise will affect a large mileage of Interstate routes along the Atlantic and Gulf coasts (Wright and Hogan, 2008; Hsiang et al., 2017). Relocating highways to inland locations as well as vertical route change may be an important part of any solution to this problem. Vertical relocation due to flooding has already happened in Utah, where a section of I-80 had to be raised 10 ft in 1986 to protect it from record high water levels of the Great Salt Lake (Morrisette, 1988). A slightly different case is the Bayonne Bridge between Staten Island and New Jersey, in which the roadway was raised 60 ft to accommodate larger ships following the completion of enlarged Panama Canal locks (Port Authority of NY and NJ, 2017). Finally, major changes to freeway standards, perhaps in the form of new generations (Weiss, 2008) responding to changing conditions or vehicles, could increase the need for route changes. Given the enormous increases in automobile travel in the last half century it is perhaps surprising there has not been more route change. But the size, speed, and weight of motor vehicles has not changed greatly during this time, removing a major source for highway change present throughout the first half of the 20th century. Most recent changes to freeways have instead been carried out to increase capacity or improve safety. Widespread adoption of self-driving cars could potentially reduce the need for higher standards by allowing vehicles to safely navigate sharper curves, steeper grades, and narrower lanes. However, if autonomous vehicles also allowed for a substantial increase in speeds, as was envisioned by designer Norman Bel Geddes (1940) in his 1939 Futurama exhibit, they could require higher standards and subsequent future route changes. More research is clearly needed to better understand and forecast changes to the American freeway system during the twenty-first century, which might draw on network based approaches that model routes as a function of their role within the larger network and urban environment (for example Levinson and Karamalaputi, 2003; Yerra and Levinson, 2005; Levinson and Chen, 2007) as well as cost-distance to predict route location. Freeway networks in other countries, differing

tremendously in age as well as political environments, should also be examined. One of the most intriguing topics requiring attention is the preservation of abandoned freeway sections in the future. Historic preservation has not had a comfortable relationship with roads or roadside landscapes, often seeing them as intrinsically inferior to mansions, battlefields, or buildings designed by famous architects, and unworthy of being taken seriously due to their ever-changing nature (Jakle and Sculle, 2011). But roads are increasingly seen as historic features worthy of preservation (CPEP, 2017). Historic roads may be those aesthetically designed, as with parkways, cultural routes that evolved over time, or engineered roads. Freeways clearly fall into the engineered category, though some may have become culturally important routes as well. Preserving roads and roadside landscapes has many challenges, and for freeways these are likely to be even greater. Maintaining historic integrity generally means preserving a structure as it was at a particular moment of time, but due to constant maintenance and rebuilding few freeways will possess this. Outdoor museums can be constructed around city streets or rural highways, but would be difficult for a freeway. Rest areas along freeways have also been seen as historic sites worthy of preservation (Dowling, 2018) and better fit the standard presevation model. The routes and structures of the Interstate Highway System have been specifically exempted from designation as historic, with the exception of a list of significant structures (FHA, 2017). This includes a 1908 stone arch bridge on I-84 in Connecticut (the oldest on the Interstate system) as well as many bridges from the 1920s onwards. The entire original Pennsylvania Turnpike is also included. But several early freeways have already been added to the National Register of Historic Places (NPS, 2017), though so far this does not include any bypassed sections. These include the Pulaski Skyway in New Jersey (completed in 1932), Merritt Parkway in Connecticut, Arroyo Seco (now Pasadena) freeway in Los Angeles, and the Davison Freeway in Detroit (the nation's first below grade urban freeway, opening in 1942). This status does not provide any legal protection for these roads or prevent change, though it could arouse citizen support to prevent changes being made, perhaps leading to a new kind of freeway revolt in favor of keeping these freeways intact. As freeways age, and perhaps especially if they are considered historic, there will eventually be nostalgia for them, as there is for Route 66 and other old highways. Two good candidates for such freeway nostalgia already exist. A 12.7 mile stretch of the former Pennsylvania Turnpike, created when two tunnels were bypassed in 1968 (Cupper, 1990), is now owned by a local conservancy which has opened it to pedestrians and bicycles, though there is no attempt at preservation or interpretation (Fig. 8). Although not intended as a preservation project, old I-75 across Tampa Bay has been preserved as the popular Skyway Fishing Pier State Park. It can be expected that the appeal of these places will grow in the future.

Fig. 8. Abandoned Pennsylvania Turnpike east of Breezewood, Pennsylvania. Source: Wikipedia.

20

Journal of Transport Geography 67 (2018) 12–23

J. Weber

Appendix A. List of freeway route changes

Route

City

State

Miles

Year

Type

Fate

I-85 I-310 U.S. 99 AZ 153 CA 275 CA 480 NY 9 WI 145 I-5 I-10 I-24 I-25 I-25 I-70 I-40 I-44 I-59 I-70 I-71/I-75 I-76 I-76 I-76 I-76 I-76 I-4 I-10/AZ 303 I-10/U.S. 60 I-10/I-19 I-10/I-95 I-15/U.S. 95 I-25/I-40 I-35 W/MN 62 I-40 I-49/I-435 I-64 I-75/OH 4 I-75/TN 153 I-85/GA 316 I-85 I-94 I-670/OH 315 I-680 FL 60 FL 826/FL 836 I-5 I-10 I-10 I-10 I-15 I-40 I-65 I-75 I-75 I-75 I-76 I-80 I-80 I-80 I-81 I-81 I-85

Charlotte New Orleans Portland Phoenix Sacramento San Francisco New York Milwaukee

NC LA OR AZ CA CA NY WI CA AZ TN CO CO MO NC MO MS CO KY PA PA PA PA PA FL AZ AZ AZ FL NV NM MN NC MO MO OH TN GA NC MI OH CA FL FL CA AZ LA FL CA TN KY FL FL MI PA CA CA OH VA VA NC

0.76 0.15 2.8 1.22 1.4 2 4.76 1.13 0.94 1.07 3.1 0.83 0.8 0.96 0.29 2.95 0.69 0.93 0.82 1.48 0.6 0.75 0.8 1.2 3.15 1.6 0.55 1.75 0.7 0.75 1.9 1.5 0.83 1.8 0.55 0.77 0.75 1 0.9 1.65 0.56 1.1 0.8 2.5 1.03 1.8 5.88 2.59 1.1 1.2 3.5 2.15 4.71 1.98 1.18 2.52 0.96 1.1 0.89 0.64 1.95

1960 1969 1974 2007 2007 1991 1973 2002 1989 2012 1988 2003 2007 2007 2000 2002 2009 1993 1992 2011 2000 2011 1980 1980 2005 2014 1995 2004 2010 2000 2002 2010 1995 2003 2008 2008 2007 2007 2007 2005 2003 1998 2007 2015 2016 2016 2010 2004 1976 1992 2016 2003 1987 1987 2009 2013 2003 2003 2007 2006 2013

Abandonment Abandonment Abandonment Abandonment Abandonment Abandonment Abandonment Abandonment Curves and hills Curves and hills Curves and hills Curves and hills Curves and hills Curves and hills Curves and hills Curves and hills Curves and hills Curves and hills Curves and hills Curves and hills Curves and hills Curves and hills Curves and hills Curves and hills Interchange Interchange Interchange Interchange Interchange Interchange Interchange Interchange Interchange Interchange Interchange Interchange Interchange Interchange Interchange Interchange Interchange Interchange Interchange Interchange New bridge New bridge New bridge New bridge New bridge New bridge New bridge New bridge New bridge New bridge New bridge New bridge New bridge New bridge New bridge New bridge New bridge

In use as freeway Abandoned In use as street In use as street In use as street Demolished Demolished In use as street Abandoned Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Abandoned Demolished In use as freeway Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished

Benson Monteagle Colorado Springs Trinidad Clayton Winston Salem Rolla Laurel Cincinnati

Tampa Phoenix Mesa Tucson Jacksonville Las Vegas Albuquerque Minneapolis Greensboro Kansas City St. Louis Dayton Chattanooga Atlanta Charlotte Detroit Columbus Walnut Creek Tampa Miami Lake Shasta New Orleans Pensacola Penasquitos Louisville Punta Gorda St. Petersburg Saginaw Pittsburgh Oakland Cleveland Lexington Lexington Salisbury

21

Notes

Now a parking garage Harbor Drive Sky Harbor Expressway West Sacramento Freeway Embarcadero Freeway West Side Elevated Highway

Monteagle Hill

Hawthorne Curve

Death Hill

The Crossing Spaghetti Bowl The Big I Crosstown Commons

Antlers bridge Cienaga Creek Hurricane Katrina Hurricane Ivan Tennessee River

Sunshine Skyway Saginaw River Allegheny River Bay bridge Carquinez Straits Cuyahoga River

Yadkin River

Journal of Transport Geography 67 (2018) 12–23

J. Weber

I-87/I-287 I-90 I-95 I-95 I-95 I-280 I-494 I-680 U.S. 17 WA 16 WA 520 I-5 I-15 I-15 I-20 I-40 I-40/I-240 I-40 I-40 I-40 I-44 I-64 I-65 I-70 I-70 I-75 I-75 I-76 I-79/I-279 I-80 I-80 I-85 I-85 I-85 I-85 I-90 I-93 I-94 I-95 I-195 I-215 I-275 I-880 U.S. 53 U.S. 460 CA 91 NY 440 Bryan Blvd Bryan Blvd VA 110 I-76 I-76 I-77

Tarrytown Cleveland Jacksonville Jacksonville Washington Toledo Minneapolis Charleston Tacoma Seattle Newhall Miramar San Bernardino Dallas-Fort Worth Oklahoma City Memphis Knoxville Winston-Salem Greensboro Tulsa Vincennes Nashville St. Louis Indianapolis Knoxville Cincinnati Pittsburgh Sacramento Salt Lake City Atlanta Atlanta Spartanburg Greensboro Chicago Boston Detroit Washington Providence Edgemont St. Petersburg Oakland Virginia Blacksburg Riverside New York Greensboro Greensboro Arlington Fulton County Somerset Kanawha County

NY OH FL FL DC OH MN CA SC WA WA CA CA CA TX OK TN TN NC NC OK IN/IL TN MO IN TN OH PA PA CA UT GA GA SC NC IL MA MI DC RI CA FL CA MN VA CA NY/NJ NC NC VA PA PA WV

3.25 1.31 0.8 0.8 1.3 0.63 0.8 1.65 2.7 1.65 2 1.58 3.04 55 77.5 3.74 11.8 1.02 18.91 14.9 2.04 3.8 4.1 5.12 2.47 6.16 1.83 57 13.2 14.15 1 2.62 2.75 8.29 11.54 23.5 2.43 1.8 13.11 1.12 1.65 60 2.3 1.1 0.45 0.5 1.35 2.49 1.6 0.77 12.67 2.29 1.13

2017 2016 2003 2008 2008 2007 2010 2007 2005 2007 2017 1971 1982 1982 1971 2012 1981 2007 1992 2008 2002 1958 2000 2014 2005 1982 1963 1972 1970 1981 1986 1979 1984 1995 2004 1978 2004 1998 1977 2009 1993 1973 1997 2017 2001 2006 2016 2006 2017 2004 1970 1964 1987

New bridge New bridge New bridge New bridge New bridge New bridge New bridge New bridge New bridge New bridge New bridge Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Relocation Tunnel bypass Tunnel bypass Tunnel bypass

Demolished Demolished Demolished Demolished Demolished In use as street Demolished Abandoned Demolished In use as freeway Demolished In use as freeway In use as street In use as freeway In use as freeway In use as street In use as freeway Demolished In use as freeway In use as freeway Abandoned in use as freeway In use as freeway In use as freeway Demolished In use as freeway In use as freeway In use as freeway In use as freeway In use as freeway Demolished Demolished In use as street In use as freeway/abandoned In use as freeway In use as freeway Demolished Demolished In use as freeway Demolished In use as street In use as freeway Demolished Demolished Demolished Demolished Demolished Demolished Demolished Demolished Abandoned Abandoned Research center

Tappan Zee bridge Innerbelt Bridge St. Johns River Trout River Potomac River

Benicia Bridge Cooper River Tacoma Narrows

Airport

Nimitz freeway

Pentagon Secure Bypass Ray's and Sideling Hill Laurel Hill WV Turnpike

Bel Geddes, N., 1940. Magic Motorways. Random House, New York. Black, W.R., 1993. Transport route location: a theoretical framework. J. Transp. Geogr. 1 (2), 86–94. Black, W.R., 2003. Transportation: A Geographical Analysis. The Guilford Press, New York. Bruce, A.G., 1937. Highway Design and Construction, Second Edition. International Textbook Company, Scranton, PA. Clay, G., 1973. Close Up: How to Read the American City. University of Chicago Press, Chicago. Clay, G., Raitz, K., 1996. Never a Stationary Highway. In: Raitz, K. (Ed.), The National Road. Johns Hopkins University Press, Baltimore. CNR (Center for National Response), 2017. Center for National Response Home Page. Available at: http://www.wv.ngb.army.mil/jitec/CNR%20Website/index.html [Last

References AASHTO (American Association of State Highway and Transportation Officials), 2017. Special Committee on U.S. Route Numbering. Available at: http://route. transportation.org, Accessed date: 13 December 2017. Abramson, L.W., 2006. 50 years of tunnels on the interstate highway system. In: TRB Structures Committee (Ed.), 50 Years of Interstate Structures: Past, Present, and Future. Transportation Research Board, Washington, DC. Atkinson, D.M., Deadman, P., Dudycha, D., Traynor, S., 2005. Multi-criteria evaluation and least cost path analysis for an arctic all-weather road. Appl. Geogr. 25, 285–307. Baumbach, R., Borah, W., 1981. The Second Battle of New Orleans: A History of the View Carre Riverfront-Expressway Controversy. University of Alabama Press, Tuscaloosa.

22

Journal of Transport Geography 67 (2018) 12–23

J. Weber

Assoc. Am. Geograph. 60, 134–152. Newton Jr., M.B., 1971. Relic roads of east Feliciana parish, Louisiana. Geogr. Rev. 61, 250–264. NPS (National Park Service), 2017. National register of historic places official website. Available at: https://www.nps.gov/nr/, Accessed date: 13 December 2017. Port Authority of NY & NJ, 2017. Navigational clearance project. Available at: http:// www.panynj.gov/bridges-tunnels/bayonne-navigational-clearance-project.html [last accessed December 13, 2017]. R&R Publishing, 1997. Mountain Directory East. R&R Publishing, Baldwin City, Kansas. R&R Publishing, 2006. Mountain Directory West. R&R Publishing, Baldwin City, Kansas. Raitz, K. (Ed.), 1996. The National Road. Johns Hopkins University Press, Baltimore. Raitz, K., Levy, J.E., Gilbreath, R.A., 2010. Mapping Kentucky's frontier trails through geographical information and cartographic applications. Geogr. Rev. 100 (3), 312–335. Rapuano, M., et al., 1968. The Freeway in the City: Principles of Planning and Design. U.S. Government Printing Office, Washington, DC. Ripple, D., 1975. History of the interstate system in Indiana. Available at: http://docs.lib. purdue.edu/jtrp/1417/ [last accessed December 13, 2017]. Rodriguez, J., 1999. The freeway revolt in San Francisco. In: Burayidi, M.A. (Ed.), City against Suburb: The Culture Wars in an American Metropolis. Praeger, Westport, CT. Rose, M., Mohl, R., 2012. Interstate: Highway Politics and Policy Since 1933, Third Edition. University of Tennessee Press, Knoxville. Schwartz, G., 1976. Urban freeways and the interstate system. South. Calif. Law Rev. 49, 406–513. Seely, B.E., 1987. Building the American Highway System: Engineers as Policy Makers. Temple University Press, Philadelphia. Shryock, J., 2011. Outer Loop construction about to restart. Available at: http://www. wsfa.com/Global/story.asp?S=14077583. [last accessed December 13, 2017]. Taylor, B.D., 1995. Public perceptions, fiscal realities, and freeway planning: the California case. J. Am. Plan. Assoc. 61, 43–56. Taylor, B.D., 2000. When finance leads planning: urban planning, highway planning, and metropolitan freeways in California. J. Plan. Educ. Res. 20, 196–214. Thomas, F.H., 1963. Evolution of a route to region relationship: a case study of the Denver and Rio Grande western railroad. J. Geogr. 62, 389–397. USGS (United States Geological Survey), 2017. National Map. Available at: https:// nationalmap.gov/ [last accessed December 13, 2017]. Vance Jr., J.E., 1961. The Oregon Trail and union Pacific railroad: a contrast in purpose. Ann. Assoc. Am. Geogr. 51, 357–379. Vance Jr., J.E., 1990. Capturing the Horizon: Historical Geography of Transportation since the Sixteenth Century. Johns Hopkins University, Baltimore. Vance Jr., J.E., 1995. The North American Railroad: Its Origin, Evolution, and Geography. Johns Hopkins University, Baltimore. Warntz, W., 1957. Transportation, social physics, and the law of refraction. Prof. Geogr. 9, 2–7. Weber, J., 2004. Everyday places on the American freeway system. J. Cult. Geogr. 21, 1–26. Weber, J., 2011. “America's new design for living”: the interstate highway system and the spatial transformation of the U.S. In: Brunn, S. (Ed.), Engineering Earth: The Impacts of Mega-Engineering Projects. Springer, Dordrecht, pp. 532–567. Weber, J., 2012. The evolving interstate highway system and the changing geography of the United States. J. Transp. Geogr. 25, 70–86. Weber, J., 2017. Continuity and change in American urban freeway networks journal of transport geography. J. Transp. Geogr. 58, 31–39. Weingroff, R., 2015a. Interstate withdrawal-substitution program legislative history and related information. Available at: https://www.fhwa.dot.gov/highwayhistory/data/ page05.cfm, Accessed date: 13 December 2017. Weingroff, R., 2015b. I-85 the Boom Belt, South Carolina. Available at: https://www. fhwa.dot.gov/infrastructure/boombelt.cfm, Accessed date: 13 December 2017. Weiss, M.H., 2008. How many interstate programs were there? Available at: http://www. fhwa.dot.gov/highwayhistory/howmany.cfm, Accessed date: 13 December 2017. Wellington, A.M., 1893. The Economic Theory of the Location of Railways, Fifth Edition. John Wiley & Sons, New York. Werner, C., 1968. The law of refraction in transportation geography: its multivariate extension. Can. Geogr. 12, 28–40. Wiley, C.C., 1935. Principles of Highway Engineering, Second Edition. McGraw-Hill, New York. Wright, K. M., Hogan, C., 2008. The potential impacts of global sea level rise on transportation infrastructure. Available at: https://climate.dot.gov/impacts-adaptations/ pdf/entire.pdf. [last accessed December 13, 2017]. Xie, F., Levinson, D., 2009. Modeling the growth of transportation networks: a comprehensive review. Networks Spat. Econ. 9, 291–307. Yerra, B.M., Levinson, D., 2005. The emergence of hierarchy in transportation networks. Ann. Reg. Sci. 39, 541–553.

accessed December 13, 2017]. CPEP (Center for Preservation Education and Planning), 2017. Historic Roads. Available at: http://www.historicroads.org/ [last accessed December 13, 2017]. Cupper, D., 1990. The Pennsylvania Turnpike, a History. Applied Arts Publishing. DiMento, J., Ellis, C., 2013. Changing Lanes: Visions and Histories of Urban Freeways. MIT Press, Cambridge. Dowling, J., 2018. Rest Area History. Available at: www.restareahistory.org, Accessed date: 18 January 2018. ESRI (Environmental Systems Research Institute), 2017. ArcGIS Desktop: Release 10. Environmental Systems Research Institute, Redlands, CA. Faigin, D., 2010. The History of Sacramento Freeway Development. Available at: https:// www.cahighways.org/maps-sac-fwy.html [last accessed December 13, 2017]. FHA (Federal Highway Administration), 2008. future interstates-high priority corridors. Available at: https://www.fhwa.dot.gov/Planning/national_highway_system/high_ priority_corridors/hpcfitext.cfm, Accessed date: 13 December 2017. FHA (Federal Highway Administration), 2016. Highway Statistics Series. Available at: https://www.fhwa.dot.gov/policyinformation/statistics.cfm [last accessed December 13, 2017]. FHA (Federal Highway Administration), 2017. Environmental Review Toolkit. Available at: https://www.environment.fhwa.dot.gov/histpres/highways.asp [last accessed December 13, 2017]. Frassinelli, M., 2010. N.J., Pennsylvania officials plan to close longtime gap on route 95. Available at: http://www.nj.com/news/index.ssf/2010/09/nj_pa_officials_plan_to_ close.html, Accessed date: 13 December 2017. Garrison, W., 1960. Connectivity of the interstate highway system. Papers Proc. Reg. Sci. Assoc. 6, 121–137. Gillespie, W.M., 1853. A Manual of the Principles and Practice of Road-Making. A. S. Barnes & Co., New York. Google, 2017. GoogleEarthPro. Available at: https://www.google.com/earth/ Harger, W.G., Bonney, E.A., 1912. Handbook for Highway Engineers. McGraw-Hill, New York. Hestermann, D.W., Dimento, J.F., Van Hengel, D., Nordenststam, B., 1993. Impacts of a consent decree on the “last urban freeway”: interstate 105 in Los Angeles County. Transport. Res. A 27 (4), 299–313. Hewes, L.I., 1942. American Highway Practice. John Wiley and Sons, New York. Hokanson, D., 1988. The Lincoln Highway: Main Street Across America. University of Iowa Press, Iowa City. Howey, M.C.L., 2007. Using multi-criteria cost surface analysis to explore past regional landscapes: a case study of ritual activity and social interaction in Michigan, AD 1200-1600. J. Archaeol. Sci. 34, 1830–1846. Hsiang, S.H., Kopp, R., Jina, A., Rising, J., Delgado, M., Mohan, S., Rasmussen, D.J., MuirWood, R., Wilson, P., Oppenheimer, M., Larsen, K., Houser, T., 2017. Estimating economic damage from climate change in the United States. Science 356, 1362–1369. Hyde, C.K., 1993. Historic Highway Bridges of Michigan. Wayne State University, Detroit. Jakle, J.A., Sculle, K.A., 2011. Remembering Roadside America: Preserving the Recent Past as Landscape and Place. University of Tennessee, Knoxville. Kozel, S. M., 2016. Woodrow Wilson Bridge. Available at: http://www.roadstothefuture. com/Woodrow_Wilson_Bridge.html [last accessed December 13, 2017]. Krim, A., Wood, D., 2005. Route 66: Iconography of the American Highway. Center for American Places, Chicago. Kroplick, H., Velocchi, A., 2009. The Long Island Motor Parkway. Acadia Publishing, Charleston, SC. Levinson, D., Chen, W., 2007. Area-based models of highway growth. ASCE. J. Urban Plan. Develop. 133 (4), 250–254. Levinson, D., Karamalaputi, R., 2003. Predicting the construction of new highway links. J. Transp. Stat. 6, 81–89. MacDonald, E., 2002. Structuring a landscape, structuring a sense of place: the enduring complexity of Olmsted and Vaux's Brooklyn parkways. J. Urban Design 7, 117–143. Malawskey, N., 2015. The Pennsylvania Turnpike's bid to replace the Allegheny Tunnels. Available at: http://www.pennlive.com/midstate/index.ssf/2015/04/pennsylvania_ turnpike_alleghen.html. [last accessed December 13, 2017]. Meinig, D.W., 1962. A comparative historical geography of two railnets: Columbia Basin and South Australia. Ann. Assoc. Am. Geogr. 52, 394 413. Mohl, R., 2004. Stop the road: freeway revolts in American cities. J. Urban History 30, 674–706. Mohl, R., 2008. The Interstates and the cities: the U.S. Department of Transportation and the freeway revolt, 1966–1973. The. J. Policy History 20, 193–226. Mohl, R., 2012. The expressway teardown movement in American cities: rethinking postwar highway policy in the post-interstate era. J. Plan. Hist. (1), 89–103. Moon, H., 1994. The Interstate Highway System. Association of American Geographers, Washington, DC. Morrisette, P.M., 1988. The rising level of the Great Salt Lake: impacts and adjustments. Bull. Am. Meteorol. Surv. 69 (9), 1034–1040. Newton Jr., M.B., 1970. Route geography and the routes of St. Helena Parish, Louisiana.

23