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Rethinking Chicago Transit

Inspiration for Chicago’s streetcar renewal is being taken, in part, from modern French tram systems that feature extensive green track and environmental mitigation measures. Image credit: J. Krause

Chicago once boasted arguably the most expansive streetcar network in the world – at its peak in the late 1930s, the Windy City hosted over 1600 track km (1000 track miles) serving 100 routes and with a fleet of over 3200 vehicles.

What makes this city in the Midwest slightly unusual is that while most US cities grew up with the automobile, Chicago was already fully built-out before the arrival of the auto age. Development was not economically viable unless the property was connected to the city and its central business district by electric rail. But with rapid growth in the early decades of the 20th century came congestion and by the 1940s the streetcar network had become overwhelmed and found itself mired in traffic.

Chicago still has the world-famous ‘L’ elevated mass transit system, introduced from the 1890s and now covering 165km (102.5 miles) of city lines, but this is expensive to maintain and currently carries a USD20bn backlog of deferred maintenance and no real prospects of paying for it. Elevated railways are also noisy and tend to undermine rather than bolster property values, struggling to attract transit-oriented development. The city has grown considerably since the introduction of the ‘L’, and the most intensive development of the latter 20th century is seen along the shoreline of Lake Michigan, much of it beyond a reasonable comfortable walking distance from where the Red line was laid out in the 1890s.

For the residents and businesses along this corridor there are two to three times as many riders per mile as the average for the heavy rail system, but instead they are served by buses that are stuck in traffic – they don’t even have dedicated bus lanes.

The way this situation has developed has left a big gap in the transit system between heavy rail and local bus. There is a role for bus rapid transit in filling that gap in the spectrum, but part of the problem is that some of the city’s corridors have such a high ridership that loading people onto small buses would require a service frequency so high that giving them signal priority would effectively shut down traffic on the surrounding grid.

A city of contrast

Two things give Chicago its distinct character: the skyscraper and its location on the southwest corner of Lake Michigan. The combination of these two aspects, the distinctly urban and the intensely natural, make it unique amongst US cities. The juxtapositions of city and nature, of skyscraper and beach, have always been striking.

Chicago was founded as the connection point between the Great Lakes and the river network that takes you further west and ultimately south to the Gulf of Mexico by the Mississippi River. Horse-drawn streetcars were seen from the late 1850s and one of the first major mechanised transport modes in the city was a cable car system introduced in the 1880s. Andrew Halliday invented it in San Francisco and the Chicago city fathers liked it so much that they installed a much larger system than any other in the US.

Yet by 1906 the cable cars were gone, replaced by an electrified network that covered the entire city. The streetcars, though, were soon stuck in the congestion of a rapidly developing city, and in the 1890s the first elevated rapid transit lines were built, showcased by the World’s Fair held in 1893. The technology was impressive for the time and quickly expanded with the use for the first time of multiple-unit control that allowed the ‘L’ to quickly grow to the eight-line system we know today.

Streetcars and the ‘L’ co-existed for half a century, but competition from the automobile, changing development patterns, challenges from a nation at war and wider traffic issues meant that the two operators, the Chicago Rapid Transit Company and the Chicago Surface Lines, found themselves in financial difficulties.

In October 1947, the newly-formed Chicago Transit Authority took over all transit operations for the streetcar, bus and rapid transit networks. By the mid-1950s it had made decisions that pretty much foreclosed any option for improving the streetcar and, like many cities around the world, the system was shuttered. The last cars ran in June 1958. Electric trolleybuses held on in the city until 1973, when they too were removed.

City development patterns have changed considerably since 1973 and urban living has become much more attractive to the current generation. In fact, going back to the late 1980s, the slow progression of people leaving the city for the suburbs has reversed and people have started to come back in. These new residents and businesses located themselves mostly downtown and along the lakefront, and that in turn generated a significant amount of congestion along key arteries across the city.

Chicago planners have been working on transport challenges for over 100 years and now is the time for a radical revision. The city tends to be somewhat conservative in how it approaches opportunities for new modes. Ironically, streetcars and light rail are viewed as a new mode, despite the city’s rich heritage.

Three key challenges

Mark Walbrun, from leading global engineering and development consultancy Mott MacDonald, and John Krause from the Chicago Renaissance (CSR) have been looking at several issues. The first is environmental: Chicago’s motto is ‘city in a garden’ and the authorities have gone to great lengths to improve the look and feel with trees, grass, flowers and green spaces.

A variety of sustainable plants are seen, many based upon the original prairie plants endemic to the area before it was developed. The difficulty is working that into a trackway, Krause explains. Green track can be attractive, but it can also mean maintenance challenges and these are issues under consideration that will allow the team to use it to a greater extent. For example, a variety of sedum plants are being studied that will change colour with the seasons and provide a habitat for pollinators such as bees and butterflies.

A second issue is average speed. As the city has grown in a rectilinear pattern, this allowed a repetitive street pattern to be developed which facilitates movements along the grid. But there are also old trails that were later turned into streets that go against the grid – these are of particular interest for transport opportunities. Looking at light rail models from Europe, mainly in France, they have looked at ways to ensure a high operating speed even on busy downtown streets.

Giving light rail dedicated lanes to operate in is essential, and the use of green track would keep cars out of those lanes and discourage pedestrians from wandering across. Chicago streets are straight and allow higher speeds than those in French cities, but they also encounter many more signalled intersections because of the ubiquitous street grid. Finding the right way to deploy transit signal priority to prevent the light rail lines from getting stuck in traffic will require some innovative design.

Thus a third issue is working with the city’s traffic department in the integration of a new street-running rail service. As the last 50 years have seen the development of a largely automobile-oriented community, the traffic signals are based upon movement of vehicles, not necessarily movement of people. Working with the Illinois Institute of Technology and a high-fidelity regional traffic simulation model, Walbrun and Krause intend to demonstrate that the combination of light rail running in dedicated lanes and with signal priority in a few high-ridership corridors would increase the capacity of the city’s streets to move people and reduce congestion downtown.

Although Chicago has a largely orthogonal city road network, it is easier to ‘move’ traffic to avoid the diagonal streets that involve six-way, or even eight-way, junctions that can be extremely slow in signal phasing. By eliminating a large number of these vehicle turning movements, traffic flow can be improved overall so that light rail and automobiles can co-exist more harmoniously with fewer stop-start movements.

In streetcar corridors, a combination of signal optimisation and dynamic signal control can optimise the flow of people and compensate background traffic for every incidence of transit signal priority. This model should allow us to build and operate the system without the expense of tunnels or elevated structures and create a network across the city that is effectively immune to congestion.

The proposal

Krause’s non-profit Chicago Streetcar Renaissance proposes a network of six routes, only going where the ridership is very high along the entire route – essentially upgrading the busiest bus corridors in the city, where streetcar operation can be demonstrated to be faster and more cost-effective.

The plan links major destinations for the first time by transit and makes vital last-mile connections between commuter rail stations and the central business district (CBD). Rather than going where there’s leftover road space, the Chicago streetcar would go where it does the most good: where demand is highest and where the congestion is worst.

The Chicago Loop is the core of the CBD and the river that goes around it. There are two main commuter rail stations and every morning 85 000 people walk from these stations over bridges into the Loop as there is currently no reasonable last-mile link. Three of the proposed lines aim to make that connection and serve the busy peak hours.

The project is inspired by the modern European tramway, which provides a better model than either the modern US streetcar – which mixes with traffic and runs at about 10km/h (6mph) – or the typical US LRT solution, which works like a commuter rail service between the suburbs and the city. While it is difficult to foresee the kind of public commitment to urban design that you see in the very best French examples, Walbrun and Krause are convinced the Chicago streetcar could go faster through the urban core – and that it will have to or it won’t succeed.

In Chicago it is possible to travel great distances from downtown and still find densely-populated and heavily-trafficked street grids with regular intersections and kerbside parking. A benefit however is that the city’s streets are mainly straight and the typical speed limit is 50km/h (30mph) compared to many European cities where 60-90% of the urban corridors have a speed limit of 30km/h (18-19mph) or less.

The city has four basic street types and for all of the proposed routes that use them green track is planned to not only contribute to a further ‘greening’ of the urban environment, but also to keep automobiles, cyclists and pedestrians off the alignment. The choice of green track would lower the overall capital cost and has additional benefits in attenuating noise, rain and stormwater and reducing the heat island effect.

While Chicago doesn’t have the broad boulevards of some European cities, there are a couple of areas where it would be possible to retain one or two lanes of car traffic in each direction on a median alignment; a few fully automobile-free sections are suggested and there are also a few sections that would operate in parkland or park-like settings along the edge of the roadway.

The recent pattern in the US has seen modern tramway projects put together by the private sector or groups outside of the transit agency, the rationale being that these groups are responsible not only for mobility but also for developing the city and its character. In short, a city has a far greater stake in its future prosperity than the transit agency.

The modelling is building a compelling argument that a new rail system can be brought through the heart of downtown without undermining traffic on the surrounding grid. For maximum effectiveness it is proposed to use 40m vehicles, each capable of carrying 300 passengers, working to minimum peak-hour service headways of five minutes.

Originally featured in December 2017 TAUT (960).