Can PRT overcome the conflicts between public transport and cycling?

Transcription

1 Can PRT overcome the conflicts between public transport and cycling? J. Meggs, F. Rupi, J. Schweizer Università di Bologna - DICAM Abstract Personal Rapid Transit (PRT) offers exceptional service characteristics, utilizing a cost-effective and space-preserving network of exclusive guideways. This article shows statistical evidence for a genuine conflict between conventional public transport services and cycling. It further shows how PRT could resolve this conflict, thus making an urban area more accessible and permeable for bicyclists and pedestrians while greatly enhancing public transport service. The high potential of PRT to attract car drivers in particular is demonstrated by surveys conducted during the BICY project of the Central Europe Programme. 1. Introduction Spatial conflicts between transport networks in urban areas hamper the efficiency of public transport while limiting the accessibility for people on foot or bike. Not only roads, traffic lights and parking lots are obstacles, but also public transport (PT) services restrict the free movement of pedestrians. Despite efforts to better integrate cycling with public transport, there are intrinsic spatial conflicts, such as exclusive bus lanes, tram lines and other space restriction in historic centers, as well as physical conflicts with the potential for serious injury and fatality. In addition, public transport services may be seen as competitors with cycling. This competition has not been sufficiently addressed in the literature. John Pucher presented in (1) a table with bike and PT mode shares for entire countries. Even though one can see a negative correlation between bikeand PT usage (see Fig. 1), the relationship is not adequately clear for comparison, as national averages represent cumulative data of highly varied urban and non-urban realities. Piet Rietveld (2) attempts to model determinants for bicycle usage associating a generalized cost to all other modes of transport. This work focuses on the relation of PT and bicycle usage, and shows how a new form of public transport, the Personal Rapid Transit (PRT), could lower this conflict by transforming it into a win-win situation. 1

2 Fig. 1: Bike mode share versus public transport mode share. A visualization of data collected by Pucher in (1). Personal Rapid Transit (PRT) is fully automated and offers passengers the opportunity to travel individually or in small groups within small, 4-6 passenger vehicles (3). Apart from the choice of destination, a trip with a comprehensive PRT network should not require any further action by the passenger, such as steering or route planning. This suggests PRT would be the most widely accessible travel option available, serving the largest part of the society. PRT vehicles arrive on-demand or they are already available at the stations, similar to a taxi stand. PRT vehicles run on grade-separated, narrow guideways. The small minimum curvature (less than 10m) and the small cross section (less than 1m 2 ) allow routing the guideways both underground in narrow shafts, elevated, and even through buildings. In historic city centers an underground implementation in small shafts just below the street surface could be an economical option. Elevated guideways are not entirely unproblematic: views and noise must be addressed. But considering that PRT could remove a large part of motorized car-traffic and parking from urban public spaces, thus resolving major conflicts with walking and cycling, elevated or underground PRT may present a far preferable system of choice; see (4-5) for socio-economic studies on PRT. The present study begins with an analysis of evident conflicts between PT and cycling whenever an investment is made in only one mode, as found by survey in the towns and cities addressed by the BICY project. In particular, we attempt to explain whether there is a systematic spatial conflict that limits the expansion of the cycling network, or whether public transport simply substitutes for bikes meaning that bikers only use the bikes in the absence of quality public transport. Thereafter we show how much demand a PRT-like service could attract and the extent to which this demand would be composed of current bicycle drivers and current car drivers. Other modes are not considered for the present work. 2

3 2. Survey methodology A detailed mobility survey in a standardized format has been developed and translated into six languages. The surveyed cities include: Ferrara, Comacchio and Ravenna in Italy; Graz in Austria, Košice, Michalovce and Spišská Nová Ves (SNV) in the Košice Region of Slovakia; Prague from Czech Republic, focused on District 5; along with Koper and Velenje from Slovenia. Target survey response was 1500 to get a +/- 2% precision even for low shares such as bicycle modal split. It has been anticipated that a street survey is not perfectly representative, even though representative gathering places such as supermarkets and schools have been targeted for the interviews. Thus, statistical corrections are performed by applying relative weights to interviewees belonging to different groups (males, females, minors, adults, seniors, and car owners). The resulting modal split has been compared with official data whenever available. For the present work we have calculated a modal split for each city. Modal split is defined as the share of regular trips performed by each mode, based on the maximum distance mode used by each individual on a regular travel day). In order to test the propensity to change modes we have proposed different transport scenarios, where each scenario represents a future transport service with certain characteristics. For the present work we focus three scenarios: Bike Scenario 2: A future bicycle network is built in a way that the interviewee can reach all his/her destination in the city on an uninterrupted bike path, will find bike parking everywhere and there are also bike sharing stations available throughout the city. Public Transport Scenario 3: The station or bus stop of a future public transport service is less than 5min walking distance from the interviewee s home, the waiting time at stops and station is never more than 5min and all vehicles are clean and air-conditioned. Public Transport Scenario 5: All characteristic of Public Transport 3 and all destinations are reachable without transfers and there is always a place to sit. This is obviously a scenario that comes close to a taxi service, or a PRT service. Each scenario was generated from the interviewees answers as to whether these characteristics would be sufficient for them to change to using bicycle or public transport on a regular basis. As we know which mode the interviewee is currently using, we could further identify the potential migration from current modes to the proposed modes given a new service offer. 3. Public transport and cycling The first analysis plotted the mode share of cycling versus the mode share of PT in the surveyed city (see Fig. 2a). In analogy with Fig. 1 we see a negative correlation, but looking at individual cities the negative relationship between 3

4 bike mode shares and PT mode shares becomes more clear. Yet, we need to be aware that we are looking at cities in different economical development stages: There is one group of new Eastern EU Member States like the Czech Republic and Slovakia with low bike shares, but high PT shares. Western EU countries generally have less PT use but a higher bike share. Slovenian cities are an exception as they show a PT mode share similar to Western European cities, but cycling is not yet as developed. (a) Fig. 2: (a) Bike mode share vs. PT mode share and (b) Bike mode share vs. Private car mode share as found by the BICY mobility survey. Among Western European cities, there is a clear negative correlation between public transport share and bike share, confirming the results of Pucher (1), even though more is required in support for this hypothesis. There is not such a clear correlation between bike share and car share, as shown in Fig. 2(b). Most Eastern EU cities have a low car mode share, while the Slovenian and Western EU cities have a higher share of car traffic. But in neither group does the bike mode share change significantly with the car mode share, except that for three Western cities, cycling appears to grow linearly with car share. In an attempt to understand the negative correlation between PT and bike use, we have : (i) analyzed the interviewees who say they would change to regular bike use in case of an ideal biker city (Bike Scenario 2); and (ii) we have determined the interviewees who declared they would change to the regular use of PT in case of an ideal conventional PT city (PT Scenario 3). Figure 3(a) shows the share of current PT users of those who expect to change to cycling provided all characteristics of Bike Scenario 2 are implemented, while Fig. 3(b) shows the share of current bike users of those who changed to PT mode in case all characteristics of PT Scenario 3 are provided. If all people were equally likely to switch to the new Scenario (Bike or PT), then the relative magnitudes of the modal splits for the modes that are reduced should correspond to those of the current modal split after the change. This is almost the case: in Fig. 3(a) we see 30%-40% of Eastern EU cities from all interviewees switching modes, which is close to their current modal split. Same is true for western EU (b) 4

5 countries with the exception of Graz where no current PT users want to switch to the bike. In Fig. 3(b) the share of bike users from those changing to PT reflects the current bike modal split. The exception is again Graz where many bike riders say they would change to a good PT service. There seems no definitive evidence that an improved PT is attracting particularly the demand from current bicycle riders. (a) Fig. 3: (a) Share of current PT users of those who would change to bike mode provided all characteristics of Bike Scenario 2 are implemented. (b) Share current bike users of those who changed to PT in case all characteristics of PT Scenario 3 are provided. The other hypothesis to be tested is whether a dense public transport network limits the expansion of cycle ways which in turn limits the number of cyclists. To this end, we plotted the cycling index (exclusive cycleway km / inhabitant) as a function of the PT mode share (see Fig. 4). It suggests that the PT networks do limit the implementation of exclusive cycle tracks per inhabitant. (b) Fig. 4: Cycle index versus PT mode share. 4. Potential for PRT Since PRT is grade separated by definition, there is no risk that PRT will limit space for cycle ways. The potential of PRT to attract current individual transport users has been demonstrated. Figure 5(a) shows the projected modal 5

6 split for PRT (PT scenario 5) after its city-wide introduction, whereas Fig. 5(b) shows that the share of car drivers among those who changed to PRT is very substantial. (a) Fig. 5: (a) Projected share of PRT after a city-wide introduction. (b) The share of former car drivers among those who say they would change to PRT. 5. Conclusions It has been shown that there is considerable evidence that existing Public Transport systems do limit the expansion of an exclusive cycle network, which in turn limits the diffusion of bicycle usage. It has further been explained why PRT, as novel public transport system utilising exclusive, grade-separated guideways, can overcome this problem. In addition it has been shown that PRT can attract a large portion of current car drivers, which would add a second major contribution to creating a much more supportive and desirable environment for cyclists and pedestrians, perhaps allowing the realization of idealized carfree cities, as detailed by the work of Crawford (4) and others. Acknowledgements The BICY project has been supported by the Central Europe Programme and co-financed by ERDF under contract number 2CE108P2. Bibliography (1) John Pucher, Transportation Quarterly, (from various transport ministries and depts., latest avail. year) (2) Piet Rietveld, Vanessa Daniel, 2004, Determinants of bicycle use: do municipal policies matter? Transportation Research Part A 38 (2004) (3) J.E. Anderson 1978, Transit system theory, Lexington Books, Lexington, MA. (4) Joel Crawford, 2000, Carfree Cities, International Books, ISBN , (b) 6

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