Ambassador Bridge Research Articles

Paste, aggregate, or air? That is the question.

The Ambassador Bridge between Detroit, Michigan, and Windsor, Ontario, has served for almost 100 years as North America's busiest international border crossing. But in 2025, the Ambassador will be replaced by the new Gordie Howe International Bridge. The Gordie Howe is a cable-stayed bridge, with two massive 220 m tall concrete piers on opposite banks of the St. Claire River, a single clear span of 853 m, and 42 m of clearance over this busy waterway. To ensure durability in this harsh freeze-thaw environment, air-entrained concrete is specified throughout. And, to ensure the quality of air entrainment, the ASTM C 457 Procedure C, Contrast Enhanced Method is employed. While a similar automated microscopic approach has been in use for well over a decade according to EN 480-11 Determination of air void characteristics in hardened concrete, this is the first large-scale application of automated air void assessment in North American infrastructure. According to the ASTM Procedure C, the air void characteristics are determined through digital image processing, while the paste content may be determined by either mix design parameters, manual point count, or 'other means'. Of these three options, point counting is used for Gordie Howe; but in parallel, during each point count, the digital image coordinates and phase identifications for each evaluated stop are recorded. This allows for training of a neural network, for automated determination of paste content, as demonstrated here.

Front Cover: Iridium Diphosphine Complexes Featuring Pendant Lewis Acids: Efforts toward Selective Heteroarene Borylation (Eur. J. Inorg. Chem. 8/2023)

The Front Cover displays an iridium-based bridge, which has been used for the borylation of an N-heterocycle, 2-methylpyridine. Inspiration for this design comes from the Ambassador Bridge, North America's busiest international land border crossing, which connects Windsor (Canada) and Detroit (USA). This bridge is located just outside the University of Windsor main campus. DemBoryl Co. stands for Demchuk Borylation Company, a nod to the first author's family name. Graphic design by Ms. Abigail Morris. More information can be found in the Research Article by M. W. Drover and co-workers.

The Impact of COVID-19 on the Movement of Trucks Between Canada and the US: Evidence from the Ambassador Bridge

The ongoing COVID-19 pandemic has closed land borders for non-essential travel between Canada and the US since the middle of March 2020. This paper explores if the pandemic has had a significant impact on the patterns of truck movements between the two countries. The volume of trucks that crossed the Ambassador Bridge (busiest land border in Canada) between August 1, 2019 and February 28, 2021 is analyzed. We found that truck volume dropped only during the first two months of the pandemic. Truck traffic increased significantly in May to reach higher than normal levels and then normalized after November 2020.

Studying border crossing choice behavior of trucks moving between Ontario, Canada and the United States

The effectiveness of trade between Canada and US relies heavily on land borders. This study uses GPS data to explore the movement of trucks across four major border crossings in southwestern and southeastern parts of the Canadian province of Ontario. Multinomial logit models are estimated to examine the route choice decisions of trucks using the four crossings. While observed crossing time has a significant and negative influence on the observed choices, its impact is generally inelastic. More importantly, the geographic location of truck trip origins and destinations appear to play a more significant role in choosing the border crossing, suggesting that geography is at play when it comes to the choice of a land border. Finally, the results suggest that long-haul trips tend to favor the Ambassador Bridge crossing that connects Windsor, Ontario to Detroit, Michigan.

Integrating a Computable General Equilibrium model with empirically calibrated transportation models for border crossing investment analysis

Computable General Equilibrium (CGE) models have been used extensively for assessing the economic impacts of transportation policies and projects. Most freight-related applications use stylistic representations of trade flows, commodity flows, and vehicles flows. This study proposes a framework that migrates from a stylistic CGE modelling approach by explicitly linking empirically calibrated transportation models of border crossing activities to a CGE model of the global economy. The framework incorporates stochastic queuing and mode choice modelling to comprehensively measure the impacts of border crossing investments. Border crossing scenarios include a 35% reduction in delay; a 4-min reduction in delay; and a reduction in delay resulting from the addition of one extra lane of capacity to each Canadian border crossing. Results suggest that the effects of border crossing investments and priorities are highly sensitive to delay modelling and mode splits, and less sensitive to mode shifts that result from investments. The proposed approach suggests Ambassador Bridge, Sarnia, and Fort Erie are the three most important border crossings for Canada's export competitiveness. A comparative analysis reveals that disregarding the real-world characteristics of the transportation system can result in large errors in the estimated impacts of border crossing investments on Canada's exports.

‘Oddly Shaped Emptinesses’: Capital, the Eerie, and the Place(less)ness of Detroit in Jeffrey Eugenides’s Virgin Suicides

ABSTRACTDrawing on critic Mark Fisher’s typology of the weird and the eerie (particularly his focus on the eerie as the sensation of nothing where there should be something), as well as Nancy Fraser and Rahael Jaeggi’s critiques of capitalism as an institutionalised social order, this paper uses Jeffrey Eugenides’s 1993 novel The Virgin Suicide to take up the significance of place and placelessness in contemporary American culture and literature. Set in the Detroit suburb of Grosse Pointe in the early 1970s, The Virgin Suicides simultaneously disguises and reveals its sense of place, a curious and unstable tension that in turn calls readers’ attention to an entire set of unstable binaries inherent to capitalism as a social order – the separation of economic production from social reproduction, economy from polity, the natural from the human, and exploitation from expropriation. In its eerie interruptions and evocations of suburban decay, The Virgin Suicides offers a way to think about the destabilising effect of attempts to separate production from social reproduction, exploitation from expropriation, and human society from non-human nature, a toolkit that might then be used to think about (for instance) the Flint Water Crisis or the contradictions of an international border-crossing like the Ambassador Bridge.

Re-Assessing Bridge Options in the Detroit-Windsor Corridor: Economics and Pragmatism Versus Politics

For the last decade, the Government of Canada has been determined to build a new bridge across the Detroit River – the busiest trade corridor on the Canada-United States border. This drive led Canada to agree in its 2012 “Crossing Agreement” with Michigan to basically finance the entire project and to take all of the financial risk related to its future operations. Yet, these blanket commitments may prove problematic as project costs estimates for its “Gordie Howe Bridge” project continue to grow. Official project estimates were re-set in April 2018 to C$4.8 million – 17% above the original C$4 billion budget. The proposed construction of the Gordie Howe Bridge comes at a time of significantly declining traffic volumes across the Canada-U.S. border. Traffic on the Ambassador Bridge, the main full service crossing in the Detroit-Windsor corridor, was down 44% between 2000-2017. With traffic stagnating, toll revenues are unlikely to grow in the years ahead. This paper lays out the issues around the Gordie Howe project and calculates the estimated required annual Canadian Government subsidy to the Bridge and related infrastructure. It compares three scenarios: status quo, a doubling of tolls, and a tripling of tolls. Under the most optimistic scenario, Canadian taxpayers, by the terms of the Crossing Agreement, will be required to subsidize the Gordie Howe Bridge a rate of US$100 million per year. The paper then assesses an alternative approach: embracing the proposal by the owners of the Ambassador Bridge to build a new privately funded span adjacent to the existing crossing. The estimated cost of achieving basically an equivalent outcome in infrastructure functionality would be C$420 million - less than one-tenth of the cost of the Gordie Howe project. Ultimately, the paper asks, how much is public ownership and control of a bridge worth? The paper concludes that the significant financial liabilities surrounding the Gordie Howe Bridge suggest that the project be shelved.

Examining the Variability of Crossing Times for Canadian Trucks at the Three Major Canada–U.S. Border Crossings

Land borders connecting Canada and the United States are vital transportation facilities for the two countries. Truck crossing times at these facilities can have a significant impact on the performance of the economy. To date, knowledge about border crossing times has been limited due to lack of detailed data on the Canadian border. This article explores and models the patterns of crossing times at the three major land crossings connecting Canada to the United States: Ambassador Bridge, Blue Water Bridge, and Peace Bridge. The analysis is based on 387,775 border crossing truck trips that were generated between Canada and the United States over a course of twelve months. Seemingly unrelated regression (SUR) models are estimated to evaluate the seasonal and hourly crossing times of Canada- and U.S.-bound trips on each border crossing, controlling for traffic intensity in the models. The SUR modeling approach is chosen to control for potential cross-model correlations. The results suggest that crossing times at the border vary by season and hour of the day. Crossing times also vary by direction of traffic and by type of day (i.e., weekday vs. weekend). Traffic intensity has a significant influence on crossing times at two of the crossings but not the Blue Water Bridge. Finally, crossing times are more variable during the summer season and tend to be higher during the late evening hours and past midnight.

Where We're Going, We'll Need Roads! Building the Bridge to the Future

In a world where global economies are increasingly interdependent, the United States, and its North American counterparts, Canada and Mexico, are booming sources of international trade. Now, more than ever, global competitiveness necessitates developments in U.S. infrastructure, especially at major border crossings where congestion and poor infrastructure create bottlenecks interfering with the free movement of goods. Questions pertaining to international border crossings circle the debate at the most crucial international border crossing in North America: the Ambassador Bridge, which spans the Detroit River between Detroit, Michigan, and Windsor, Ontario. A legal battle rages over the proposed construction of a new publicly owned bridge that will compete with the eighty-six-year-old privately owned bridge. Many questions surround this topic, including whether the United States may allow the construction of a bridge that competes with a private individual’s livelihood. Is there a compelling case for a government taking in favor of public infrastructure? Should a private individual be able to own a major international border crossing? Additionally, in anticipation of construction of a new bridge, what will be the implications for the community that must give up its property to make way for the construction? This Comment will focus on the conflict over the construction of the New International Trade Crossing (NITC), also known as the “Bridge to the Future,” in competition with the Ambassador Bridge and its relevance to the conversation of border infrastructure. It will further demonstrate some of the pitfalls in the private ownership of an international border crossing—as well as some that inhere in government ownership—arguing for a new infrastructure model that promotes collaboration between the public and private sectors. Ultimately, this Article will argue that, like the NITC, future border infrastructure projects should be developed through the use of public-private partnerships (hereinafter “P3s”) to promote North American trade development.

Short-term prediction of border crossing time and traffic volume for commercial trucks: A case study for the Ambassador Bridge

Short-term forecasting of traffic characteristics, such as traffic flow, speed, travel time, and queue length, has gained considerable attention from transportation researchers and practitioners over past three decades. While past studies primarily focused on traffic characteristics on freeways or urban arterials this study places particular emphasis on modeling the crossing time over one of the busiest US–Canada bridges, the Ambassador Bridge. Using a month-long volume data from Remote Traffic Microwave Sensors and a yearlong Global Positioning System data for crossing time two sets of ANN models are designed, trained, and validated to perform short-term predictions of (1) the volume of trucks crossing the Ambassador Bridge and (2) the time it takes for the trucks to cross the bridge from one side to the other. The prediction of crossing time is contingent on truck volume on the bridge and therefore separate ANN models were trained to predict the volume. A multilayer feedforward neural network with backpropagation approach was used to train the ANN models. Predicted crossing times from the ANNs have a high correlation with the observed values. Evaluation indicators further confirmed the high forecasting capability of the trained ANN models. The ANN models from this study could be used for short-term forecasting of crossing time that would support operations of ITS technologies.

Characterization of International Origin–Destination Truck Movements Across Two Major U.S.–Canadian Border Crossings

In 2013, 3.9 million trucks crossed between the United States and Canada at the Ambassador Bridge or the Blue Water Bridge. These trucks accounted for 43.1%, by value, of all truck trade between the two countries. GPS pings that tracked the movement of Canadian-owned trucks over a span of 1 year were used to characterize freight activities at the two Canada–United States border crossings. (A “ping” is a GPS data record that identifies the location of a subject at a given point in time. The term is commonly used in the information technology and communications industries.) A total of 172,000 and 82,000 crossing events were identified and analyzed at the Ambassador Bridge and the Blue Water Bridge, respectively. This paper describes the development of origin–destination data pertaining to truck trips that utilize the two border locations. The paper also includes an estimation of the industries involved in individual trips, on the basis of those trips’ start and end locations. The combination of origin, destination, crossing time and location, and industry provides an immense amount of information on the nature of international truck movements at the Canada–United States border. The resulting spatial patterns provide evidence that the two border crossings are used for both short- and long-range trips that include locations on the West Coast and the southern U.S. border. Although crossing times did not vary considerably by industry, they were influenced by the distance of the trip: short-distance journeys had shorter crossing durations, on average.

Forgotten Partnership at 20-Something

Just days after the terrorist attacks of n September 2001, President George W. Bush gave one of the most important speeches of his presidency before a joint session of congress, reshaping the trajectory of American foreign policy. Seated in the upper deck of the house of representatives was British Prime Minister Tony Blair, who had flown across the Atlantic just to attend. Bush declared, no truer friend than Great Britain. Once again, we are joined together in a great cause.Cue the hand-wringing in Canada. Suddenly, the decades of shared history that spawned the amorous cliches of thousands of speeches had been turned on their head. What had become of Canada's with America? Canadians, after aU, had taken in thousands of passengers stranded when American airspace was closed on 9/11. What happened to being each other's best customer? What about aU those trucks that cross the Ambassador Bridge? Don't we share the world's longest undefended border? What about the peaceful coexistence between elephants and mice?Doubts about the strength of the ties that bind Canada and the United States together have multiplied in recent years. Former US Ambassador to Canada Paul Cellucci's infamous quip that trumps or the cancellation of official visits to Ottawa by Bush in 2003 and Secretary of State Condoleeza Rice in 2005, reportedly over Canada's decision to stay out of Iraq and ballistic missile defence, respectively, left a chill on bilateral relations.North America, and Canada-US relations more narrowly, have not suffered from inattention in the last decade. However, the policy focus has been heavily dominated by a Faustian bargain between security and economics that has become more entrenched since President Barack Obama assumed office in 2009. Coupled with recent efforts by Obama and Britain's David Cameron to redefine the US-UK relationship as an essential one, many are left wondering whether there was ever anything special about CanadaUS relations. American officials openly praise the contribution and sacrificed being made by Canadians in Afghanistan, one could be forgiven for suspecting that the US talking points might actually read insert NATO ally here.In 1984, Charles Doran argued that Canada-U S relations were at a similar set of crossroads. Structural asymmetries, divergent interests, and both strategic and tactical missteps by Ottawa and Washington risked undermining the postwar comity and cooperation between the two countries. Through the 1970s, Canada and the United States had moved along divergent paths, abandoning many elements of cooperation, institution-building, deference, exceptionalism, and exemptionalism that had until then characterized Canada- U S relations. Such was the uncertain state of bilateral relations in the period that Ronald Reagan's ambitious call for a accord in 1979 seemed wildly out of step. Reagan's ascendancy to the White House dramatically reasserted America's role as leader and underwriter of a liberal global economic system. At the same time, Canada struggled to find its place in the world, trapped between the economic nationalism of initiatives like the national energy program and its dependence on an open global economy for its economic survival. It was a crossroads for the relationship, indeed.Yet only a year after publication of Forgotten Partnership: CanadaUS Relations Today, as Reagan and Prime Minister Mulroney sang When Irish eyes are smiling together in Quebec City, one might have concluded that Doran's assessment of the state of Canada-US relations was overly pessimistic.1 The two leaders had just committed to negotiating a comprehensive free trade agreement, two thirds of the continental accord, which seemingly heralded the renewal of partnership. The dramatic reversal of Canada's economic posture in response to Reagan's chaUenge had set the two countries on a course for a dramatic deepening of the relationship through economic ties. …

Development of methodology for quantifying the effectiveness of priority crossing programs at land border crossings

Land border crossings face the challenge of putting through increasing traffic while managing delays to crossing users, especially during periods of high demand as well as security alerts. Besides physical infrastructure expansion in the long run, a number of efficiency-oriented system management measures, namely priority crossing programs and associated queue jump lanes, have a potential role to play in the short and medium run. Although these are perceived to be beneficial, means to evaluate their performance are lacking. This paper reports research on the development of predictive models for the quantification of the effectiveness of priority crossing initiatives and associated queue jump lanes for the Ambassador Bridge (between Windsor and Detroit) in addressing delay and throughput problems at land border crossings. The findings illustrate the merit of predictive models for assessing the effectiveness of priority crossing programs and queue jump lanes in reducing delay and increasing productivity.

Prediction and Display of Delay at Road Border Crossings~!2009-10-09~!2010-01-07~!2010-04-15~!

Land border crossings in North America that serve high volumes of automobile and truck traffic experience congestion and delay, resulting in adverse effects on level of service, transportation costs, commerce, tourism, and the environment. Although efforts have been underway to expedite the customs inspection process (without compromising security), improving the reliability of delay estimates and real time dissemination of information remains a challenge. This paper reports research on intelligent technologies and methodological advances that can be used to automatically predict private and commercial vehicle queues and delays and display information to motorists, border crossing authorities, and other decision makers on a real time basis. The availability of such traveler information can be useful for making pre-trip and enroute travel decisions by private motorists as well as commercial vehicle operators regarding departure time and choice of border crossing location (if applicable). Such a system would enable motorists and carriers to avoid severe delays and commercial vehicle fleet efficiency gains can be achieved. Border crossing authorities can use the results to better match the processing capacity with demand for service. Research steps include the use of a calibrated microsimulation model of the Windsor-Detroit Ambassador Bridge crossing, development of artificial neural network (ANN) models for predicting queues and delay, imbedding these models in a traveler information system that uses sensor data as input and produces delay predictions for dissemination on dynamic message signs and other media on a real time basis. This system is tailored for border crossings with high volumes of private and commercial vehicle traffic.

Contributions of Diesel Truck Emissions to Indoor Elemental Carbon Concentrations in Homes Proximate to Ambassador Bridge

Contributions of Diesel Truck Emissions to Indoor Elemental Carbon Concentrations in Homes Proximate to Ambassador Bridge

Contributions of diesel truck emissions to indoor elemental carbon concentrations in homes in proximity to Ambassador Bridge

Ambassador Bridge, connecting Detroit, Michigan and Windsor, Ontario, is the busiest international commercial vehicle crossing in North America, with a large percentage of heavy duty diesel trucks. This study seeks to examine the contribution of diesel truck traffic across Ambassador Bridge to indoor exposure patterns of elemental carbon (EC), a common surrogate for diesel exhaust particles, in homes in close proximity to the bridge. We also aim to understand the relative importance of home ventilation characteristics and wind speed. Measurements were collected as part of the Detroit Exposure and Aerosol Research Study (DEARS). Residential indoor and outdoor EC measurements were collected over five consecutive 24 h periods in both the summer and winter at 16 homes in close proximity to Ambassador Bridge. Ambient concentrations and meteorological data were collected at a central-site monitor, and home air exchange rates were estimated using a perfluorocarbon tracer. The contributions of ambient concentrations and Ambassador Bridge, and potential effect modification by wind speed and home ventilation status were quantified with regression analyses. Both ambient concentrations and the percentage of time a home was downwind from the bridge were associated with an increase in indoor concentrations. Ambient concentrations significantly contributed to indoor concentrations regardless of wind speed category but were a greater influence in home experiencing calm winds. The effect of the percent of time downwind variable on indoor levels was only significant in homes where the ventilation status was high. The distance a home was from the bridge tollbooth complex was not significantly associated with indoor concentrations. We conclude that diesel traffic emissions related to Ambassador Bridge may have an impact on indoor EC exposures. Given that people spend the majority of their time indoors, it is important to evaluate the impact of traffic-related pollution in the home environment.

Evaluating Suspension Bridge Cables on North America's Busiest International Crossing

The main cables of the Ambassador Bridge—carrying four lanes of traffic over the Detroit River between Detroit, Michigan, and Windsor, Ontario, Canada—have recently been inspected internally for the first time, after 78 years of service. The bridge has a suspended main span of 1,850 ft, with back spans consisting of trusses supported on steel bents. The main cables comprise 37 strands of 218 wires each, protected with red lead paste. The wires are No. 6 gauge, cold drawn and double galvanized, with a specified minimum tensile strength of 215 ksi. Cable strength was calculated by means of the procedures of NCHRP Report 534: Guidelines for Inspection and Strength Evaluation of Suspension Bridge Parallel Wire Cables. Four locations were inspected along the length of each cable, and wire samples removed for testing. All three models presented in NCHRP Report 534 were used to estimate cable strength: the simplified strength model, the brittle wire model, and the limited ductility model. Modifications to the NCHRP procedure were required for the unloaded backstay locations. The results of the evaluation showed the cables to be in very good condition, with a calculated factor of safety of 2.70, which was based on the limited ductility model. The reduction in strength from the as-built condition was less than 10% at the worst location.

Intra-urban variability of air pollution in Windsor, Ontario—Measurement and modeling for human exposure assessment

There are acknowledged difficulties in epidemiological studies to accurately assign exposure to air pollution for large populations, and large, long-term cohort studies have typically relied upon data from central monitoring stations. This approach has generally been adequate when populations span large areas or diverse cities. However, when the effects of intra-urban differences in exposure are being studied, the use of these existing central sites are likely to be inadequate for representing spatial variability that exists within an urban area. As part of the Border Air Quality Strategy (BAQS), an international agreement between the governments of Canada and the United States, a number of air health effects studies are being undertaken by Health Canada and the US EPA. Health Canada's research largely focuses on the chronic exposure of elementary school children to air pollution. The exposure characterization for this population to a variety of air pollutants has been assessed using land-use regression (LUR) models. This approach has been applied in several cities to nitrogen dioxide (NO 2), as an assumed traffic exposure marker. However, the models have largely been developed from limited periods of saturation monitoring data and often only represent one or two seasons. Two key questions from these previous efforts, which are examined in this paper, are: If NO 2 is a traffic marker, what other pollutants, potentially traffic related, might it actually represent? How well is the within city spatial variability of NO 2, and other traffic-related pollutants, characterized by a single saturation monitoring campaign. Input data for the models developed in this paper were obtained across a network of 54 monitoring sites situated across Windsor, Ontario. The pollutants studied were NO 2, sulfur dioxide (SO 2) and volatile organic compounds, which were measured in all four seasons by deploying passive samplers for 2-week periods. Correlations among these pollutants were calculated to assess what other pollutants NO 2 might represent, and correlations across seasons for a given pollutant were determined to assess how much the within-city spatial pattern varies with time. LUR models were then developed for NO 2, SO 2, benzene, and toluene. A multiple regression model including proximity to the Ambassador Bridge (the main Canada—US border crossing point), and proximity to highways and major roads, predicted NO 2 concentrations with an R 2=0.77. The SO 2 model predictors included distance to the Ambassador Bridge, dwelling density within 1500 m, and Detroit-based SO 2 emitters within 3000 m resulting in a model with an R 2=0.69. Benzene and toluene LUR models included traffic predictors as well as point source emitters resulting in R 2=0.73 and 0.46, respectively. Between season pollutant correlations were all significant although actual concentrations for each site varied by season. This suggests that if one season were to be selected to represent the annual concentrations for a specific site this may lead to a potential under or overestimation in exposure, which could be significant for health research. All pollutants had strong inter-pollutant correlations suggesting that NO 2 could represent SO 2, benzene, and toluene.

Intra-Urban Variability of Air Pollution: Monitoring and Modelling of PM2.5, PM2.5-10, and NO2

WM3-PD-02 This research was undertaken as part of the Border Air Quality Strategy (BAQS), an international agreement between the governments of Canada and the United States. Concerns about air quality in the Windsor–Detroit region have led to a number of air health effects studies being undertaken by Health Canada. The use of central site monitoring stations for assigning exposure has been cited as a potential source of exposure misclassification. Several of the health studies being undertaken for BAQS by Health Canada are investigating the chronic exposure of children to air pollution, which has required the development of local exposure studies. One of which is the development of an intra-urban monitoring network to measure a variety of ambient air pollutants. This monitoring data are being used for the development of models to predict exposure to outdoor air pollution at an intra-urban scale. There have been several intra-urban monitoring and modelling studies undertaken in Europe and North America. Land-use regression (LUR) models that have been developed using similar monitoring data have been used with success in improving exposure estimates. However, most intra-urban monitoring studies have frequently measured only NO2. Therefore, less data are available for particulate matter on such a scale. This is mainly due to the difficulty of measuring particulates at many locations, which this type of modelling requires. In Windsor, LUR models have so far been developed for NO2 using data collected with Maxxam Analytic passive samplers. NO2 concentrations ranged from 6.9 to 20.2 ppb, with a median of 12.0 ppb and were significantly correlated with distance to the Ambassador Bridge (P < 0.0001), length of expressways and highways within 50 m (P < 0.0001) and length of major roads within 100 m (P = 0.0475) in simple regression analyses. A multiple regression model including proximity to the Ambassador Bridge and proximity to highways and major roads predicted NO2 concentrations with an R2 = 0.77 on an annual basis. Measurements of NO2, PM2.5, as well PM2.5-10, were conducted throughout 4 seasons over a 2-week period in 2005 using low-flow particulate monitors located in the backyards of 50 Windsor residences. The range of PM2.5 over the 4 seasons was 6.4 to 29.3 μg/m3, initial Kriging suggests the border crossing heavily influences the higher concentrations. The LUR model is under development and results will be used to compare the relationships between NO2, PM2.5, and PM2.5-10.

The Security and Prosperity Partnership

The tragic events of 11 September 2001 marked a watershed in the lives of most of the world, but they affected most especially those in the United States and its two land neighbours, Canada and Mexico. For the first time in history, America was gravely threatened from within by terrorists who managed to assimilate into its open society and attack buildings in its most symbolic cities. Not since Pearl Harbor-which was geographically, if not emotionally, distant from the North American mainland-had there been an attack on the United States by enemies from abroad. Unlike World War II, the wilful destruction of iconic buildings and the loss of innocent lives in New York and the nation's capital brought home the very real threat posed by individuals and groups bent on challenging the economic and political might of the world's only remaining superpower. After several centuries of fighting many battles far from its borders, the United States found itself in a war in the very kitchen of the American home.One of the first decisions taken by the US administration in the hours following the destruction of the World Trade Center buildings and the attack on the Pentagon was to seal off the country's land, air, and seaports, which are the lifeline of billions of dollars in commerce and the route of millions of people who enter and leave the US on any given day. The result was total chaos, particularly along the two land borders that formally divide the US from its North American neighbours. Individual lives were disrupted to an unimaginable degree, while the flow of goods and services, on which most of North American industry depends, came to a virtual standstill. All of a sudden the open border that characterized the boundary between the US and Canada slammed shut, while the border with Mexico-already much more controlled-became a logistical nightmare for the millions of bona fide travelers, importers, and exporters who rely on a smooth and efficient border for their economic and social intercourse.Who can forget the images of miles and miles of tractor-trailers backed up on the Canadian side of the Ambassador Bridge, or of the lonely, unmanned crossing that only had a traffic cone to signal that it was closed for the day? Traffic jams at Otay Mesa or Nuevo Laredo stretched as far as the eye could see, while hapless immigration and customs officials struggled with implementing the emergency closure order that came from Washington. For at least 72 hours, the entire machinery of commerce set up under the North American free trade agreement came to a screeching halt. Factories in all three countries that relied on just-in-time deliveries for their production were forced to suspend activities, while trucks, trains, and cars spent hours and sometimes days waiting to clear the border and resume their itineraries. In short, the terrorists, whose primary objective was to destroy landmarks in New York and Washington, ended up devastating the very nervous system of North America.A few weeks after 9/11, the foreign ministers of Mexico and Canada met at the Mexican embassy in Washington to discuss the crisis that had so severely affected the economies of their countries. This was the first occasion since the entry into force of NAFTA that prompted the US's two neighbours to schedule an urgent political consultation to decide what individual and joint steps could be taken to mitigate the impact of the actions at the borders. They also wanted to ensure that the basic lifelines among the three trade partners be kept open until a negotiated agreement with the US was reached on measures that would significantly improve border security and give the authorities in Washington the necessary confidence to gradually resume operations at the dozens of land and bridge crossings on their northern and southern borders. Unfortunately, it wasn't possible at the time to come up with a bilateral strategy between Canada and Mexico on this issue. Then-Foreign Minister John Manley told his Mexican counterpart that Canada's relationship with the US was different from Mexico's, and that security and intelligence cooperation under NATO and other military and law enforcement agreements made it necessary for Ottawa to negotiate separately with its American ally. …