The Potential for Orbital Public Transport Services in the Greater Dublin Area

Orbital routes are often considered a costly idea that is unpopular with transport users. Yet many cities provide them in a successful, often revenue-generating context. Those that do take a Network Effect approach to service design. The idea of orbital routes within the Greater Dublin Area (GDA) transport network has been around for some time, referenced for example in the 2002 Dublin Transportation Office (DTO) “Platform for Change” Strategy, the 2006 MVA “Dublin Bus Network Review” consultants’ study and most recently the National Transport Authority (NTA) Greater Dublin Area Draft Transport Strategy 2011-2030, where two notional orbital Quality Bus Corridors (QBCs) are referred to (Figure 1 below). This paper examines current strategies to serve orbital demand and looks at the potential for and barriers to delivering such services. Future demand models indicate that strategic mode share targets cannot be met without orbital services. Analysis of residential and employment land-uses in a quadrant of the GDA indicates potential for effective orbital services. Further study is recommended to analyse the optimum design and routing of any such services. These need to be efficient and direct with high levels of transferability between services. They should also closely reflect the urban structure (or “Core”) strategy recently adopted by Dublin City Council. Current (draft) transport strategy appears to exclude key development centres, notably in disadvantaged areas, which could be integral to an effective and socially accessible transport network. Introduction Recently, major advancements have been made in Dublin’s public transport system such as the introduction of RTPI / AVL (real time passenger information / automatic vehicle location technology), the new “Leap Card” electronic wallet and the ongoing restructuring of Dublin Bus routes. The dublinbikes on-street bike rental scheme has been recognised worldwide and attitudes towards active travel are noticeably changing [1]. Figure 1: References to Orbital QBCs in (a) 2002 DTO “Platform for Change” (b) 2006 MVA Study and (c) 2011 NTA Draft Transport Strategy Broderick, O’Connor: Orbital Rapid Transit in GDA 29-30th August 2012 University of Ulster Proceedings of the ITRN2012 Introducing high quality orbital QBCs could be an evolutionary step building on these progressive measures and would require a framework of inputs involving planning authorities, transport agencies, communities and government. Most importantly it would tie transport strategy properly in with land use policy, something not currently achieved by current draft strategy. This in turn can lead to a fully mobile city with connected, healthy neighbourhoods. The main argument for orbital QBCs is the Network Effect benefit they would deliver. Understanding the Network Effect Many northern and central European cities boast a transport system that provides comprehensive mobility, serving anywhere-to-anywhere trips in a relatively timely and efficient manner. Berlin, Hamburg and Zurich are a number of cities than can be designated within such a category. The most oft-cited reason for optimality in urban transport is density. It is contended here that density and land use planning has an important though much overstated role to play. Even at low-medium densities, a population of 10,000 or more the equivalent of a medium-sized Irish town can live within walking distance of a transport hub [2]. Paul Mees, in particular, argues that the density-patronage relationship is less clearcut than often claimed and that the most important determinant of ridership is service quality [3]. A central requirement in this regard is an idea called the “network effect”. Very little has been written on this subject although esteemed authors such as Thomson acknowledge its importance [4]. The most authoritative understanding of the concept has been given by Mees and his model is worth recounting here. To explain it at its most basic level a theoretical city is imagined which has 10 un-networked (in this case north-south) routes serving a grid of evenly populated districts (see Figure 2, below left) with similarly even trip distributions. Figure 2: “Squaresville”: the Network Effect illustrated (Source: Mees, 2002) In this model, using conservative assumptions (low-medium densities and a 30-40% propensity to choose public transport), a total of approximately 6% of all trips are likely to be by public transport. Doubling the frequency of those routes, at standard elasticity of demand rates (say, a 50% propensity to transfer), would lead to a potential 9% of trips served by public transport. In this case costs have doubled but patronage has only risen by 50%. However, if instead of doubling frequencies 10 new networked (i.e. east-west) routes are added a different picture emerges (see Figure 2, above right). In this model, using the same assumptions, a total of 40% of trips are likely to be by public transport. Now, for the same cost outlay, patronage and revenue have both risen more than 6-fold. This is a theoretical model assuming an even population distribution. In a typical urban scenario many of the routes could be loss-making or feeder routes, however the overall network stands to gain as a result. Most businesses understand that such cross-subsidy is 1 The idea of Healthy Neighbourhoods is well explained in Barton et al [2] and alludes to the design of urban areas such that communities can enjoy active healthy lifestyles in a risk-free, amenable environment. Absence of noise / air pollution and opportunities for active travel are key components considered, as is high social mobility via public transport. Proceedings of the ITRN2012 29-30th August 2012 University of Ulster Broderick, O’Connor: Orbital Rapid Transit in GDA essential to develop a viable market. This, according to Mees, is nearly always a feature of successful transit cities [5]. Joining up Dublin’s Neighbourhoods The question is prompted whether the principle of the network effect is appropriate for Dublin’s urban structure. The Dublin City Council Development Plan 2011-2017 has a Core Strategy (see Figure 3 below right) [6]. A critical element of the strategy is the designation of Key District Centres and Key Developing Areas. Another vital component of the Core Strategy is three arterial Economic Corridors along with a Strategic Green Network. This vision suggests an orbital network of well connected district centres with strong connections to the centre. Figure 3: Dublin City Council Development Plan 2011 – 2017 Core Strategy Demand for the orbital and “networked” trips suggested by the City Council’s Core Strategy not only exists but is very strong according to land use demand models prepared by the NTA. Figure 4.6 of the NTA Draft Transport Strategy (reproduced below) indicates that fully 56% of morning peak trips in the GDA are orbital, while 39% of trips are either arterial or inbound [7]. Many, possibly even a majority of these arterial trips are likely to be “networked” trips, i.e. requiring a transfer to reach their end-destination. In 2030 the percentage of orbital trips is forecasted to reduce to 46%. But if it is assumed that a significant share of arterial trips require some transfer, at least half possibly two-thirds of all trips will not be served by the Strategy. That is unless a high level of orbital service is provided, in turn with a high level of transferability. Without an orbital service the forecast suggests that the NTA draft Transport Strategy cannot inherently deliver the high levels of mode transfer to which it alludes. Figure 4: “Figure 4.6” of the NTA draft Transport Strategy Potential for and Barriers to Orbital Public Transport Services The concept of a quality orbital system interlinking with quality arterial routes to form an urban transport network appears to be a critical feature then. Research was undertaken as part of an undergraduate dissertation by Colin Broderick to identify the potential for and barriers to implementing an orbital rapid transit network in Dublin [8]. The study was restricted to the north eastern quadrant of Dublin, generally described as everything east of the Ballymun Road Corridor. This sector of the city is characterised by low-medium density suburban housing of mixed socio-economic status (although with large pockets of 2 The NTA Draft Transport Strategy, unlike previous transport strategy documents does not explicitly state mode share targets. Some reference is made to contributing to targets (45% car; 20% bicycle) set out in the national government’s Smarter Travel Policy Document Broderick, O’Connor: Orbital Rapid Transit in GDA 29-30th August 2012 University of Ulster Proceedings of the ITRN2012 disadvantaged areas). The area also comprises of extensive ageing manufacturing zones containing declining industry. Investment is low in the area and transport to outside of the area is essential for employment opportunities to many [9]. The first stage of the research was to identify which orbital lines would be used for assessment. A review of existing strategy and published policy for public transport in Dublin identified certain relevant options:  2030 Vision Draft National Transport Authority Strategy [10]  Dublin Bus Network Review (the “MVA Study”) [11]  Currently released elements of Dublin Bus Network Direct [12]  Dublin City Development Plan 2011 – 2017 Core Strategy [13] A map was extracted from the Open Street Map database. The extracted map was then imported into Adobe Illustrator where the various strategies were simplified and drawn by eye onto the map. Google Earth provided baseline aerial photography predominately dating from the 2010 period for the majority of the Dublin city area. The study area was mapped for the main uses that generate trips for public transport such as employment/industrial areas, schools, hospitals, shopping centres, etc. 2030 Vision Bus Strategy Map. The