Parking Guidance Systems

Parking Guidance and Information (PGI) systems use variable message signs (VMS) to provide drivers with information on the location and the availability of spaces in car parks. They have been in use since the 1970s, initially implemented in Aachen ( Germany ). Over subsequent years, their use has increased and it has been estimated that over 50 systems of this type are in operation worldwide.

Earlier systems involved limited function signs with very simple space counters and availability display units. However the technology used has evolved and nowadays electronic message signs are able to display a full range of messages and symbols.

A typical PGI system consists of m onitoring equipment to establish the flow into and out of the car park, a central computer to process the counts and control the dissemination of information to the public via VMS or other media such as radio or a web site. VMS displays should be located at suitable decision points on the network, so that a driver’s journey time to a vacant space is minimised.

The aim of PGI systems is to manage the available parking spaces in highly populated urban areas more efficiently. Studies have shown that PGI systems can influence drivers’ choice of car park and reduce the time spent looking for a parking space. This affects traffic flows and queueing outside the most popular car parks. The overall effect is a reduction in congestion and air pollution which will lead to enhancement of urban areas.


Parking Guidance and Information (PGI) systems use variable message signs (VMS) to provide drivers with information on the location and the availability of spaces in car parks. They have been in use since the 1970s, initially implemented in Aachen ( Germany ). Over subsequent years, their use has increased and it has been estimated that over 50 systems of this type are in operation worldwide (Polak et al., 1990; Axhausen et al., 1994; Tsopelas, 2000; Thompson and Bonsall 1997).


Earlier systems, such as that in St Helier (Gercans, 1984), involve limited function signs with very simple space counters and availability display units. However the technology used for the systems evolved dramatically. Nowadays, electronic message signs are able to display a full range of messages and symbols. On an operational level, recent PGI systems consist of the following elements and equipment (Polak et al., 1990; DfT, 2003)

  • driver information equipment which may be of various types, with the most usual being the variable message signs (VMS) panel located at roadside;
  • occupancy loops or automatic vehicle identification (AVI) equipment that can count the number of vehicles entering and exiting the car parks, and closed circuit television (CCTV) equipment ;
  • television cameras monitoring traffic status in the streets;
  • electronic payment devices using electronic, inductive, magnetic or smart card technology;
  • electronic parking meters used to control how long vehicles park in the streets, charging fees and checking availability;
  • a control centre with an occupancy rate equalizer (equilibrium) that controls the display of information on the VMS;
  • a telecommunication network and computers to exchange data (information) between the above systems.

A review of a typical PGI system structure can be found in Polak et al. (1990) and DfT (2003) and Spencer (2001) . A typical PGI system consists of the following stages. M onitoring equipment at the parking areas establish the flow into and out of the car parks in order to calculate the number of available spaces. Car park count data are transmitted back to a central location and processed before being presented to the public via VMS or other media such as radio or a web site. VMS displays are located at suitable decision points on the network, so that a driver’s journey time to a vacant space is minimised.

Nowadays, advanced PGI systems can present a range of real time information, including waiting times and prices. These systems can also be developed jointly with other aspects related to traffic management that provide users with real-time information on road accidents, traffic congestion, traffic flow restraints and the location of parking facilities (Viena, 2003).

Why introduce parking guidance and information systems?

In general, PGI systems aim to encourage a more efficient use of the parking stock, to reduce queuing at car parks and parking search times (Polak, et al.,1990), and consequently to cut search traffic.

Problems generated by the lack of parking spaces in predominantly, highly populated areas are manifesting themselves as increased traffic congestion and longer travel times. These in turn lead to a lower quality of life and a lower level of accessibility for citizens (Verhoef et al., 1995; Miles et al, 1998; Ison and Wall, 2002). Searching for parking spaces may be responsible for as much as 30% of the traffic on main urban roads (Allen, 1993) and time spent searching for a parking place can often reach up to 40% of the total travel time (Axhausen, 1994).

The use of PGI systems can assist drivers to improve network efficiency and accessibility by reducing time wasted searching or queuing at car park entrances. This in turn reduces congestion on the road network near the controlled car parks, benefiting other traffic (DfT, 2003). Non-quantifiable benefits include an improved public image of car park management, and reduction in driver frustration. Based on various studies (Gercans, 1984; Allen, 1993; Axhausen et al.,1994; Polak, et al.,1990; DfT,2003 ).

Demand impacts

Benefits from a PGI system will be greatest when the demand for off-street parking is approximately equal to supply. If there is an excess demand for off-street spaces, PGI is expected to have little impact on problems caused. This is because the signs continuously would show ‘no space’. Also, if demand is sufficiently less than supply and spaces are easy to find, the system provides little benefit.

It is assumed that if drivers access parking information before they start their journeys, and if car parks are full, they can choose not to use their cars; go to the nearest available car park; or change their final destination. However t here is also a potential danger that by helping the motorist, they reduce the probability of drivers using an alternative more sustainable mode (DfT, 2003).

  • PGI systems are likely to be less effective in areas where (Converge-D3.3.1, 2000; Kempter et al. 1995):
  • there is a high proportion of drivers with local knowledge;
  • many drivers have private car parking spaces; and
  • there are significant through traffic movements.
Responses and situations
Response Reduction in road traffic Expected in situations
May delay departure until spaces are available in desired car park, or just more spaces generally if information accessed before departure. This may reduce congestion, but impact on vehicle kilometres by car is likely to be negligable.
Availability of car parking at different car park than usually visited will result in changes in the route followed to trip end.
With no parking availability at desired destination, drivers might consider changing destination for some trip purposes, e.g., shopping and leisure trips to out of town centres.
If known lack of parking availability causes drivers to use alternative more sustainable modes.
By increasing the convenience of travel by car, e.g. reducing total journey time and frustration of searching for a parking space.
= Weakest possible response = Strongest possible positive response
= Weakest possible negative response = Strongest possible negative response
= No response

There is however some problem in getting drivers to make use of such systems. Axhausen et al (1994) found that drivers tended to adopt their own strategy and only turn to the parking guidance when this failed. Other studies show that drivers take limited notice of the parking guidance systems and then for certain types of information. Attitudinal and stated preference studies by Allen (1993) and other studies reviewed by Thompson and Bonsall (1997) bear this out.

Supply impacts

Improved utilization of off-street long stay parking may improve the accessibility of short stay on-street parking areas. Reduced search traffic and shorter journey times will release some capacity that will improve the speeds that were originally lower around the car parks.

Financing requirements

The cost for PGI varies according to the equipment, interface between the PGI and the parking sites and the communication system that will be used for the system. The exact costs of a PGI system depend on the vendor selected to provide the equipment, the interface method between the PGS and the car parks, and the communication system. Cost estimate for a PGI with 24 dynamic message signs in San Jose (USA) suggests the total cost would be $4.1 million, of which nearly $3 million is design and equipment cost (Spencer, 2004).

Studies suggest that the benefits of such systems can exceed the cost. A cost-benefit calculation made for SouthamptonPGI suggested that the PGI signs were economically viable (with an economic rate of return of 91%) and over a five year period the benefits outweighed the cost of installation and maintenance (Converge-D3.3.1, 2000). It found that annual reductions in vehicle operating costs and annual increases in revenue for the public transport operator exceeded the annual operating costs of PGI, with a benefit-cost ratio of 1.85 (Kempter et al.1995).

Expected impact on key policy objectives

Parking guidance and management can improve network efficiency significantly, and environment and accessibility at some degree. Improved parking information from PGI systems can raise the public’s image of the area, which can lead to improved revenue generation within that area. It can lead to safer driving behaviour, as drivers are guided straight to an available space (UTMC, 05a Final Report Page 47). The efficiency and accessibility benefits from reduced searching may be associated with some reductions in environmental intrusion and accidents, but these will depend on the local circumstances.

Contribution to objectives


Scale of contribution



By minimizing queues for parking; spreading the excess parking demand; helping to obtain desired occupancy levels and hence improving parking turnover rates of car parks.

This increases road capacity through reduced parking queues.

Makes controlling parking operations easier with better data management, also allowing easier decision processes and implementation of plans.

  By reducing parking queues and search traffic and by helping to eliminate illegal parking.
  By reducing air pollution, and visual intrusion, thus enhancing use of urban areas.

When on-street parking and search for parking is reduced.

Also more stringent supervision leads to less illegal parking, a major cause of accidents.

  Where reduced congestion and pollution improves environmental quality, thus the image of the area.

When used for Park and Ride sites, bus operators would benefit from increased passenger due to increased usage of the site.

Car parking operators will benefit from greater parking use of off-street parking.

There will be cost incurred both in implementing and maintaining PGI systems.

= Weakest possible positive contribution = Strongest possible positive contribution
= Weakest possible negative contribution = Strongest possible negative contribution
= No contribution

Changes in pollutant emissions and fuel consumption due to PGI are most closely related to changes in overall travel time (Converge-D3.3.1, 2000). Kempter et al. (1995), for example, reported annual reduction in pollutant emissions due to PGI at a Park and Ride site in Munich (Munchen), Germany . However their estimate was made based on questionnaire results for the number of drivers using Park and Ride due to PGI and average changes in the distance travelled by these users. The DfT’s sponsored project on UTMC (UTMC03, 2000) suggests:

  • Parking guidance systems can lead to a non-trivial reduction in the vehicle emissions under extreme conditions of good guidance and drivers who do not know where there are likely to be vacant parking spaces.
  • The emissions reductions depend on the level of demand for public parking places in relation to the supply. As the difficulty of finding a place increases, measured by the unaided search time or distance, then the benefits increase.
  • Emission reductions through benefits to would-be on-street parkers who fail to find an on-street place may take place. This could be a significant factor under circumstances where demand for on-street places is high.

Typical benefits are 2% reductions in emissions of CO and HC and 1% in emissions of NOX and PM 10S. Although larger benefits are possible under favourable conditions. It should be noted that these benefits may decrease as on-street parking places increase because drivers take one of these rather than travel to another off-street public car park (Thompson, R G 2001). In summary, the limited information so far available suggests that parking guidance systems and media information can contribute to the reduction of emissions by decreasing search times, particularly under congested conditions.

Expected impact on problems

Provision of parking information is expected to shorten the time spent on finding a parking space and waiting before parking a car, reduce irritation associated with it and lead to efficient and increased use of parking facilities. Reductions in on-street parking and cars driving around searching for spaces are expected to make road traffic smoother and improve the environment. Making parking facilities within the area easier to use is expected to reduce concerns about travelling to the applicable district by car and contribute to the revitalization of the region such as by improving the image of the area. The evidence from Southampton (Converge-D3.3.1, 2000) and Frankfurt (Axhausen et al., 1994) indicates that parking guidance information reduces the average time spent parking at times when there is a large demand for parking.

Contribution to alleviation of key problems


Scale of contribution


Congestion-related delay

Contribution may be greater when established in an affluent area or combined with low car housing development.

Congestion-related unreliability

By shortening the time spent on finding a parking lot and waiting before parking a car.

Community severence

By reducing search traffic.

Visual intrusion

By reducing queues for parking.

Lack of amenity


Global warming

By reducing traffic-related CO2 emissions.

Local air pollution

By reducing emissions of NOx, particulates and other local pollutants.


By reducing traffic levels and by reducing parking search.

Reduction of green space

By reducing pressure for new parking provision.

Damage to environmentally sensitive sites

By reducing traffic volumes and queues around these areas.

Poor accessibility for those without a car and those with mobility impairments


Disproportionate disadvantaging of particular social or geographic groups

Car drivers unable to access information prior to travel may be disadvantaged, but since few people currently to this, impacts are negligible.

Number, severity and risk of accidents

By reducing search traffic and illegal parking.

Suppression of the potential for economic activity in the area

By improving the efficiency of the local road network and parking supply. By improving perceived parking availability.
= Weakest possible positive contribution = Strongest possible positive contribution
= Weakest possible negative contribution = Strongest possible negative contribution
= No contribution

Expected winners and losers

Winners and losers




Large scale freight and commercial traffic

These are high value journeys – less time spent in congestion the greater the vehicle utilization- where illegal on-street parking is reduced, loading/unloading time will also reduce.

Small businesses

With less search traffic and queues, perception of the area improves hence there are more visitors to the area.

High income car-users

High income associated with high value of time. Total journey time will be reduced.
People with a low income -

People with poor access to public transport


All existing public transport users

Reduced search time use will reduce congestion and hence improve public transport reliability

An increase in public transport due to encouragement to use park and ride, and a modal transfer will have a knock on effect thus improving efficiency of public transport.

People living adjacent to the area targeted

They may benefit from reduced search traffic and parking queues.

People making high value, important journeys

Reduced travel time will result in time savings (easier parking and reduced congestion).
The average car user

Where they are able to shorten total travel time, and reduce fuel costs.

Also allows them to find the best parking space suited to their needs and location.

= Weakest possible benefit = Strongest possible positive benefit
= Weakest possible negative benefit = Strongest possible negative benefit
= Neither wins nor loses

Barriers to implementation

Scale of barriers
Barrier Scale Comment
Legal No legal barriers.
Finance Some limited financial support may be needed.
Governance Coordination is needed between cities and car park operators.
Political acceptability Unlikely to be contentious.
Public and stakeholder acceptability Unlikely to arouse opposition.
Technical feasibility Prove technology.
= Minimal barrier = Most significant barrier

Parking Guidance and Information System in Southampton , UK
Parking Guidance and Information Systems, Japan

Parking Guidance and Information System in Southampton, UK

The case study reported here is taken from ‘Evaluation Results and Comparative Assessment, Southampton Case Study’ prepared by Heusch/Boesefeldt GmbH for EUROSCOPE-TR 1023.The report was produced in 1999.


Prior to 1992, rotating prism car park VMS were used to display one of two legends; ‘full’ or ‘spaces’ in Southampton. Later as a part of the ROMANSE Project, a new city-wide system of car park VMS combining directional as well as occupancy number information, has been installed. Two of the signs, which are further out from the city centre, display the total number of spaces in each of the three city centre areas, while others display information for named car parks (Figure 1). At the end of 1996, the rotating prism signs were replaced by dot-matrix signs and a further seven dot-matrix car park VMS were installed as part of the ENTRANCE project. The ROMANSE pilot project has been expanded within the framework of the ROMANSE II - EUROSCOPE project and has moved from an experimental pilot project to a full demonstration project in daily operation, with wide implementation of the integrated traffic management measures. There is now a total of 26 car park signs providing real-time information of the number of spaces available in each of the main off-street car parks.

Figure 2 illustrates the system structure. Vehicles entering and leaving the car parks are detected traversing the loops in the entry/exit lanes of the car parks and the data is transmitted to the control centre where, at two minute intervals, the number of vacant spaces in each car park are calculated and passed to the signs on street. Off-street parking in the city was divided into three main areas. Signs for these areas and associated car parks were colour coded. This was to enable drivers to identify car park information which was relevant to the area of the city they wanted to visit.

Figure 1: Southampton parking guidance information system


Rotating prism PGI Dot-matrix PGI, courtesy of Hampshire County Council (

Figure 2 Southampton PGI System Structure


Courtesy of Hampshire County Council (

There are some 4,000 off-street parking spaces in Southampton city centre and, overall, there is adequate parking in the city, except possibly during the busy Christmas shopping period and the Boat Show period (Southampton Boat Show is the busiest in Europe). The parking guidance signs are located in Southampton city centre and on approach roads shown in Figure 3.

Figure 3 Parking Guidance VMS Location Plan


source: EU EUROSCOPE (1999)

Impacts on demand

The parking guidance VMS were evaluated using questionnaire interview surveys on two previous occasions; December 1994 (within ROMANSE) and December 1996 (within ENTRANCE). Further questionnaire surveys were undertaken during the Boat Show week in September 1998 and the pre-Christmas period of December 1998. At this time the complete parking guidance system had been operating successfully in Southampton for the previous 18 months, and so the majority of the road users were accustomed to this type of real-time information.

Table 2 compares the results of all surveys undertaken in Southampton to investigate the effectiveness of the parking guidance signs since the introduction of the pilot system in 1994. Before the city-wide upgrading to dot-matrix signs, only 38% of drivers who noticed a PGI sign looked at the information (this survey was undertaken in December 1994). In subsequent surveys, this figure rose, and varied from 58% to 74%. It was found that the proportion of drivers looking at the information is higher for drivers visiting the city centre less frequently, and greater at times of peak parking demand. 34% to 41% of drivers said they ‘always’ or ‘nearly always’ use the parking guidance signs. Overall, some 8% of the sample claimed to have changed their parking destination as a result of the information.

Table 2 Comparison of results from all Parking Guidance Sign surveys undertaken in Southampton (EUROSCOPE, 1999)

Some Highlights

Dec 94

Dec 96

Sept 98

Dec 98 (Signs not working)

Dec 98

Sample size






% of people who had decided to park in a specific car park BEFORE setting off on their trip











% of people who ‘always’ or ‘nearly always’ use the parking guidance signs






% of people who found it either ‘very easy’ or ‘easy’ to find a space











% of people who noticed a parking guidance sign on their way to the car park











Of these, % of respondents who looked at the information






Of these, % who claimed that they changed their parking destination as a result of the information











Therefore, % of the total sample who changed their parking destination






% of people who think that such signs are ‘necessary’ in Southampton











Note: there are some inconsistencies between the different surveys (see details, EUROSCOPE, 1999)

It appears from the results of the interview surveys and the car park occupancy surveys that demand for parking does not yet exceed supply, even at peak periods such as the Boat Show and the pre-Christmas Saturday shopping. The majority of drivers do not usually need parking guidance information, but they think it is necessary, perhaps to assist them at certain times when there are fewer spaces available. This is because 80-86% of drivers decided to park in the car park (where they were interviewed) before they set off from their home and 85-96% of drivers found it ‘easy’ or ‘very easy’ to find a parking space. At a point in the future when demand outstrips supply, the signs are expected, in theory, to have much more benefit.

Impacts on environment

Another EU Project, CONVERGE (2000) estimated the environmental impacts of the introduction of citywide dot-matrix PGI signs in Southampton . These estimates were based on differences in the ‘before’ and ‘after’ times spent searching and queuing for parking spaces and other information such as, speed related emission factors from the HBEFA manual on emission factors, idling emission factors from the MODEM emissions model and fleet composition data. It was estimated that these reductions could be 6% and 15% of the fuel consumption and pollutant emissions for a 10km and 3km trip respectively during the periods of high demand (Converge-D3.3.1, 2000).


A cost-benefit calculation was made for SouthamptonPGI based on the cost of installation and maintenance of the dot-matrix PGI signs and the benefits associated with the reductions in the times spent searching and queuing for parking spaces. The benefits included reductions in distance travelled, time spent parking, vehicle operating costs and fuel consumption. The value of time used was £8 per hour. Based on the assumption that the reductions in the times spent searching and queuing for parking spaces would apply to 79 days per year over a period of 5 year, PGI system was found economically viable with an economic rate of return of 91%. This showed that over a five year period the benefits outweigh the cost of installation and maintenance in Southampton (Converge-D3.3.1, 2000).

In general PGI systems are implemented part of an integrated urban traffic management system. This was also the case in the Southampton PGI that combined by the STOPWATCH, TRIPlaner and ARTEMIS projects (see Converge 2000 for details) in order to provide real time travel information and guidance cross modes. The total cost of the ROMANSE pilot and ROMANSE II demonstration is given in the following table.

Table 3 Cost figures for ROMANSE and ROMANCE II

Costs in Million EUR


ROMANSE II demonstration















11.2 )

Barriers and conflicts

Securing medium to long-term funding was thought to be harder to do when the ROMANSE products are implemented county wide. It is expected that it may also create technical hitches due to moving from the pilot schemes to wider implementation (REC, 2004).

On the other hand, political conflicts were effectively avoided by implementing the PGI part of the integrated policy of the region. However what is not clear is the legal responsibility of travel information provision which might lead to legal action if wrong information were to lead to financial losses for users, or operators.

Parking Guidance and Information Systems, Japan

The case study reported here is taken from ‘Japan Institute of Contraction Engineering’s Regional Intelligent Transport Systems (ITS) Website’ that was designed as an aid to measure the benefits of regional ITS. The regional ITS casebook titled ‘Benefits from ITS Deployment in Japan’ has been created to provide an overview of the magnitude of the benefits of various services being considered for adoption and to provide information that will help when explaining the usefulness of regional ITS to a third party.


This case study evaluates the benefits of Parking Guidance and Information provision implemented in fours cities in Japan. Figure 1 shows the expected benefits from PGI systems and their evaluation criteria with the representative measures used in these case studies.

Figure 1 Classification of benefits and the method used to assess these benefits


source: ITS Policy Program Division, Road Bureau Ministry of Land, Infrastructure and Transport , Japan

Increase in efficiency and use of parking

(1) Dispersed use of parking facilities

In Toyota City , the occupancy rate of an underground parking facility at Shin-Toyota Station, one of the most crowded parking places, was reduced from 130% to 117% after the introduction of parking information signs. Figure 2 shows the gradual reduction in occupancy rate to 111% following the launch of the web-based and cellular phone-based services that allows drivers to get information prior to their departure.

Figure 2 Changes in occupancy rate of Shin-Toyota Station underground parking fig6

source: ITS Policy Program Division, Road Bureau Ministry of Land, Infrastructure and Transport , Japan

(2) Reduction in waiting time before parking

At the same parking place in Toyota City, gradual introduction of the same parking guidance systems decreased the waiting time for vacancies by more than half (Fig. 3).

Figure3 Changes in waiting time for vacancies at Shin-Toyota Station underground parking fig7

source: ITS Policy Program Division, Road Bureau Ministry of Land, Infrastructure and Transport , Japan

Smoothing traffic flow

(1) Reduction of illegal on-street parking

After the introduction of a parking guidance system In Sapporo City, the number of vehicles illegally parked on streets was reduced dramatically: a quarter on weekdays and halved at weekend and holidays.

Figure 4 Changes in number of vehicles illegally parked on streets


source: ITS Policy Program Division, Road Bureau Ministry of Land, Infrastructure and Transport , Japan

(2) Reduction of wandering vehicles

In Toyota City , surveys showed that the average time required to park, measured from the time a car arrives in the central part of the city to the time the car is parked, was reduced from 12 minutes to 6 minutes. Similarly in Okayama City, 50% of the respondents feel that the time required to park has been (will be) reduced by about 10 minutes to 15 minutes, and the actual time reduction reported was averaged 13 minutes (Fig. 5).

Figure 5 Reductions in time required to park in Okayama City


1. The figures above indicate time reductions reported by respondents who thought the time required to park had been or will be reduced. 2. Even if the respondent had never used the system, he/she was asked to respond by assuming the use of such system. (source: ITS Policy Program Division, Road Bureau Ministry of Land, Infrastructure and Transport , Japan )

(3) Alleviation of traffic congestion

In Sapporo City , it is reported that the degree of congestion measured at a point on National Highway Route 36 ( Sapporo Ekimae-dori) decreased by 0.28 point from 0.74 to 0.46. In Toyota City , the vehicle kilometres travelled by vehicles using parking facilities decreased by 47%. It is also reported that the number of vehicles illegally parked on streets also decreased. PGI systems have contributed to the alleviation of traffic congestion in both cities.(Fig. 6).

Figure 6 In-vehicle kilometres travelled by vehicles using parking facilities


Improvement of environment

(1) Reduction in air pollution and global warming

In Toyota City , CO2 and NOx emissions from vehicles using parking facilities have decreased dramatically in line with decreases in search traffic and parking queues (Fig. 7).

Figure 7 Changes in CO2 and NOx emissions from vehicles using parking facilities


Enhancement of user satisfaction

(1) User convenience

In a questionnaire survey conducted in Okayama City , more than 90% of system users said that the time required to find parking and the time spent waiting for vacancies had shortened, and irritation had been or will be eliminated. About 70% of users replied that uneasiness associated with finding a parking space had been or will be eliminated. (Fig. 8).

Figure 8 Elimination of irritation and uneasiness of parking search


(2) Utility and intention of use

According to a questionnaire conducted in Toyota City, from all the different information techniques (electronic sign, internet and phone based PGI) being used, more than half of users are satisfied with cellular phone-based information services, while only about one third are satisfied with parking information signs alone (Fig. 9).

Figure 9 Effectiveness of PGI system in central Toyota City


A survey by the Toyota Municipal Government indicates that the ratio of location change is as high as 90% among cellular phone-based information recipients, suggesting that cellular phones will become a very effective information medium as they become more widespread (Fig. 10).

Figure 10 Parking change ratio by information medium


Sapporo City also provides telephone-based PGI service (fax-on-demand information service). The number of accesses to this service has nearly quintupled from 1994 (371 request) to 2000 (1467 request).

Other Studies

Other studies can be used to show the general benefit on several aspects affected by Parking Guidance and Information Systems:

  • Travel time: The evidence from Southampton .(Converge-D3.3.1, 2000) and Frankfurt-am-Main(Axhausenet al., 1994) indicates that parking guidance information reduces the average time spent parking at times when there is a large demand for parking. Results from surveys in Southampton at different times of year found that drivers using city centre car parks reduced the average time spent searching for a space by 50% - from 2.4mins to 1.2mins.
  • Destination: In Southampton , 7% to 12% of drivers who notice parking guidance information changed parking destination due to it. A survey of over 600 people in Valencia , Spain found that 61% of drivers’ route choices were influenced by the information on VMS signs and 30% had changed their parking destination as a result. In both cities it was observed that a substantially higher proportion of infrequent visitors change parking destination due to parking guidance information (Converge-D3.3.1, 2000).
  • Diversions: “A study in Leicester examined the effect of parking guidance information on arrival rates at car parks and found that changes in the reported availability of parking spaces significantly influenced arrival rates at relevant car parks.” (Wright and Withill 1992). Information relating to Park and Ride has been measured to have a very small impact on the numbers of drivers using Park and Ride (Converge-D3.3.1, 2000).
  • Travel distance and speeds: An optimization model (Thompson, 2001) showed that PGI minimizes parking queues by spreading the excess demand between the number of facilities having an adequate supply of parking. Thus the total distance travelled can also be reduced, by directing cars away from the central car parks to other available car parks near their entrance links. This can potentially reduce vehicle emissions as a consequence of increasing average vehicle speeds within that area such as a city centre.
  • Congestion: A number plate survey in Torbay (UK), a seaside resort, showed that parking guidance information decreased queuing slightly at popular car parks and increased patronage at a less popular car park (Andrew and Hillen 1980). In Utsunomiya , Japan , there were 74% (weekday figure) fewer vehicles observed to be queuing at the entrance of car parks (Thompson, 1998) as a result of introduction of a PGI system.

Contribution to objectives

The following policy contributions from PGI systems were achieved in the case studies.

Contribution to objectives
Objective Southampton Japan Comment
  Increases availability of (turnover of) off-street parking and reduces search traffic.
  Improves the quality of street by reducing illegal parking and search traffic.
  The reduction in search traffic in also reduces air and noise pollution.
  There are no reported impacts on equity and social inclusion.
  The reduction in search traffic reduces the risk of accidents.
  Reduce car traffic and improves the environment, making it more attractive to shoppers and visitors.
  Increase the off-street parking efficiency. When used for Park & Ride, it helps to utilize these sites and increase use of public transport.
= Weakest possible positive contribution = Strongest possible positive contribution
= Weakest possible negative contribution = Strongest possible negative contribution
= No contribution

Contribution to problems

Contribution to alleviation of key problems


Scale of contribution



By reducing traffic searching for parking spaces.

Community impacts By reducing parking in unsuitable locations.
Environmental damage By reducing traffic searching for parking spaces.
Poor accessibility Minor impacts only.
Social or geographic disadvantage Little impact.
Accidents By reducing traffic searching for parking spaces.
Economic growth By making the area more attractive to visitors.
= Weakest possible positive contribution = Strongest possible positive contribution
= Weakest possible negative contribution = Strongest possible negative contribution
= No contribution

Appropriate contexts

Appropriate area-types
Area type Suitability
City centre
Dense inner suburb
Medium density outer suburb
Less dense outer suburb
District centre
Small town
Tourist town
= Least suitable area type = Most suitable area type

Adverse side-effects

As in other cases there is the possibility that improving access to parking may increase the number car trips into city centres unless there are other restraints operating. One possibility is an increase in parking charges since such charges impact on drivers without increasing congestion. There is also a potential danger that by helping the motorist, PGI systems can reduce the probability of drivers using an alternative mode (DfT, 2003).

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