The Effects of Park and Ride Supply and Pricing on Public Transport Demand

1 Executive summary

Background and study objectives

1.1 Arup, with Accent and the Institute for Transport Studies at the University of Leeds were jointly appointed by Transport Scotland to explore the effect of park and ride parking supply and pricing on public transport demand.

1.2 The study objectives were:

  • to investigate the extent to which (if at all) changes to park and ride supply and pricing affect public transport patronage and what alternatives would be used in the absence of formal parking facilities (Objective 1)
  • to assess the extent park and ride can influence modal shift to public transport, plus the impact on emissions and congestion (Objective 2)
  • to assess the relative importance of the factors which influence the use of park and ride facilities (Objective 3)
  • to establish the extent park and ride leads to undesirable outcomes including increased car usage (Objective 4)
  • based upon the analysis to support the above aims, to provide metrics to assist the development of guidance for appraising the impact on rail and bus demand and revenue of changes to park and ride parking policy and provision (Objective 5)
  • to identify the optimum pricing policy to maximise rail station car parking revenue (Objective 6)


1.3 The methodology combined a review of secondary data sources and a literature review with the targeted collection of primary data. The primary data were then used to develop forecasting models.

1.4 The study explored parking at railway stations, bus park and ride and Cross Forth journeys using a series of case studies:

  • For parking availability at railway stations: Bridge of Allan, East Kilbride, Perth and Kirkcaldy. 'Control' surveys were also conducted at Stirling and Falkirk High since these stations had not benefited from additional parking spaces to isolate these impacts1
  • For bus park and ride sites: Bridge of Don (Aberdeen) and Ingliston (Edinburgh)
  • For Cross Forth journeys: Inverkeithing and Ferrytoll respectively

Findings on parking at railway stations

1.5 Findings from the model indicate the change in wholly new rail trips resulting from additional parking is modest. The relationship between the number of parking spaces before and after the expansion, and the total number of new trips suggests each additional 100 spaces generates between 4 and 10 extra journeys per day based. The findings from the case study stations could be applied to other stations only with due attention to local circumstances, given that the demand impact will vary according to the specific characteristics of each station.

1.6 The findings from the primary research indicate that the mileage removed from the network from drivers switching to rail would be offset by more existing rail passengers driving to the station.

1.7 Findings from stakeholder feedback, along with the primary research highlight that CCTV, lighting and tarmac roads are an integral part of the overall station design to encourage users.

1.8 The capital cost of extending existing car parks is about £5,000-£10,000 per space, although this could be higher if decking is required. The revenue stream that could be generated from additional rail passengers would be insufficient to provide a financial pay-back in less than 10 years, though there may be instances when this is possible.

1.9 If the price for parking per day was increased by £1 (either from free to £1, or £1 to £2 for example), rail demand would be reduced by 4.9% or just 3.0% if there is ample free local parking. Furthermore, about 55% of the remaining rail passengers would park elsewhere. Regardless of the current pricing structure, any increase to parking charges would mean the revenue loss from rail passengers switching to other modes exceeding the income raised from the higher charge per vehicle.

Findings on bus based park and ride

1.10 Both Ingliston and Bridge of Don park and ride sites have sufficient spare capacity (only 50% of the spaces are occupied, so motorists are confident of getting a space). Therefore the modelling explored the impact on demand if parking spaces were removed. The findings from the modelling framework indicated demand would be reduced by 19% if there was a 10% chance of not finding a space. If the chance of not getting a space was higher (20%), demand would fall by 34%. Over 60% would make their entire journey by car if there was insufficient parking. Therefore, if bus park and ride was not available or constrained there would be a significant switch among users to making their entire journey by car.

1.11 Monitoring data indicated that there are about 1,200 park and ride trips per day using all park and ride sites in Edinburgh. This equates to less than <1% of the trips into the city centre. The small number of users of park and ride in comparison with all trips means that the impact on wider modal shift and emissions is small.

1.12 The results from the literature review, combined with the findings from the primary research, highlighted a number of essential attributes that are required to encourage usage. These include proximity to the strategic road network, availability of parking throughout the day, bus departures every 10 minutes, competitive journey times, competitive fares that are attractive versus parking in the urban centre and when the buses operate. Other desirable attributes include dedicated buses, availability of facilities, type of vehicle and branding.

1.13 Compared with the rail case studies, the small number of additional car trips from drivers travelling to the park and ride to access more frequent and / or cheaper buses is offset by the mileage removed from the network resulting from mode transfer.

1.14 The costs to operate park and ride with buses departing every 10 minutes range from £800,000 to £1m per site. For a site to break even in financial terms, about 1,200 passengers per day on a typical weekday would be required. This highlights the importance of optimising the site location to achieve a robust financial case. Evidence suggests about 20,000 daily vehicles must pass the site to attract the required demand.

1.15 Although several park and ride schemes in Scotland have been delivered, benchmarking the performance of these sites with examples elsewhere in the UK suggests there is scope to boost patronage.

1.16 Analysis of the impact of changes in fares was inconclusive in terms of being able to specify a revenue maximising fare. The findings suggested that bus park and ride demand is price inelastic, i.e. that there is scope to raise revenue through higher fares. However, this would serve to reduce the associated congestion and carbon benefits.

Findings on Cross Forth travel

1.17 The results from the primary research indicate passengers using Ferrytoll and Inverkeithing park and ride have relatively low values of time, hence implying users are choosing public transport to avoid paying the high parking charges in Edinburgh, even though the overall journey time by bus or rail is longer.

1.18 The opportunities to encourage modal shift to bus or rail appear to be affected by future parking policy and the distribution of new employment in Edinburgh. Passenger behaviour is relatively unresponsive to alternative travel options, so the scope to encourage passengers to switch between rail and bus (or vice versa) following changes is limited.

1.19 The overall journey times by public transport versus car are slower, but two factors mean the former choice remains attractive. The high frequency bus services, combined with the lower overall cost of public transport if free city centre parking is not available have contributed to the high levels of usage.

1.20 The Cross Forth public transport alternatives have limited negative impacts. With short access times to Ferrytoll and Inverkeithing, the number of passengers using park and ride towards Edinburgh has helped to control congestion on busy corridors including the A90. The current delays experienced by car drivers crossing the Forth Bridge limits the number of prospective users crossing from Fife towards Edinburgh. The proposed new crossing could release suppressed demand, with some drivers parking closer to their final destination and increasing the distance travelled, though it should be noted that the plans include a substantial investment in public transport including bus only lanes which will enhance the attractiveness of public transport across the Firth of Forth.

1.21 Potential improvements to the existing Cross Forth park and ride choices need to be considered as part of wider assessment of public transport links between Edinburgh and Fife or destinations further afield, given the characteristics of the rail and bus routes serving the corridor.


1.22 The availability of parking spaces at bus park and ride is fundamental in influencing the travel behaviour. If bus park and ride was not available or constrained there would be a significant switch among users to making their entire journey by car. Several other factors must be addressed including proximity to the strategic road network, and frequency of bus departures.

1.23 In contrast, the relationship between parking and rail demand is less conclusive. If parking availability is increased, the level of new rail demand is relatively small and the subsequent change in car distances is negligible. As a result, the case for delivering improvements must be linked to other objectives and a wider assessment will be needed.

1.24 The requirement to improve bus or rail services for Cross Forth journeys will be influenced by various factors including future parking policy enforced in central Edinburgh, the distribution of employment and the role for any demand management initiatives resulting from the proposed new Forth Crossing.