New off street parking first principles assessment

First principles assessment

Why change parking regulations and access/egress arrangements

Vehicles parked on-street interact with moving traffic, and careful account needs to be taken of the requirements of moving traffic when designing the layout of regulations at any particular location. In some locations, parking is prohibited because of highway safety requirements. In others, parking is permitted at certain times when local access needs outweigh congestion and movement concerns. Kerbside regulations determine which activities (stopping, loading or parking) can take place, when and for how long.

On-street parking is the most convenient place for drivers to park as it provides door to door access, but this disrupts the general traffic and causes delays and congestion. In a typical street with approximately 60 parked cars per km, the average speed falls by 0.75 km/h with every ten additional parked vehicles.

In general, allowing on-street parking on a major arterial will decrease capacity and increase delays and accidents due to the physical occupation of the space, manoeuvres, pedestrians appearing in between vehicles and other activities associated with parking ( Hobbs , 1979). The capacity reduction factors for adjacent lanes resulting from parking manoeuvres are given in the Highway Capacity Manual (TRB, 2000). For example, on average 20 manoeuvres reduces capacity by 20% on one lane, 11% on two lanes and 7% on three lane roads.

Large off-street car parks can generate considerable blocking back of traffic waiting to enter the facility and delays where vehicles re-join the road system. There may be a particular problem if the surrounding streets are narrow or the entrance to the car park is near to a junction. Conventional management is often used to facilitate one-way access/egress and reduce the disruption on minor roads. However, where the car park is located adjacent to a major arterial with fast-moving traffic, there may be benefits to providing storage lanes that would allow vehicles to enter/leave at lower speed to improve safety and reduce the disruption to passing traffic (Hobbs, 1979; O’Flaherty, 1996).

Demand impacts

Several empirical studies and models have shown that the availability of parking is an important influence on travel behaviour and hence the volume of traffic attracted to an area. Reducing the number of on/off street parking spaces may be more effective at encouraging drivers to use a different mode (or change destinations) than other policy measures.

Feeney (1989) suggests that this would have five main consequences on drivers:

change in parking location;
change in starting time of the journey;
change in the mode used;
change in the trip destination; or
cause abandonment of the trip.

Such area-wide schemes require careful planning; there is often public concerns over the details of the restrictions and the aesthetic impact of signs and road markings, and problems may arise if the displaced users continue to drive and park just outside the controlled area.

There is a general lack of research on the sensitivity of drivers to security issues but there is anecdotal evidence that shoppers choose to visit a particular centre on the basis of the local parking arrangements. A study by MVA (1998) found that the type of parking available is an issue; surface car parks are more attractive than multi-storeys, which are associated with difficulties in manoeuvring and poor security.

The following responses and situations are likely to be expected when on-street parking is removed from places where it disrupts moving traffic and provided in the form of off-street parking with better access and egress arrangements.

Responses and situations

Response	Reduction in road traffic	Expected in situations
		In response to limited parking availability at and final destination, some drivers choose to leave early to guarantee a space, but this is unlikely to change vehicle kilometres. If travel is made in less congested hours than departure time may effect the duration of journeys.
		Small changes may occur due to traveling to different destination when parking availability at previous location is eliminated / reduced.
		Changes in destination will occur where this allows drivers to avoid restrictive parking controls and usually results in longer journey distances.
		A few journeys may be abandoned if parking is particularly difficult.
		Where on-street parking reductions and new off-street parking sites (e.g. P&R) are accompanied by good alternative means of access.

	= Weakest possible response,		= strongest possible positive response
	= Weakest possible negative response,		= strongest possible negative response

= No response

Supply impacts

Supply impacts will vary according to type of parking. A reduction in on-street parking will increase road capacity and average speeds, and hence reduce congestion and vehicle emissions. Changes in volume of off-street parking will not alter the supply of road space, but may allow a re-designation of the function of a particular street.

Local authorities are increasingly using the planning system to control the supply of off-street parking. Most areas now have maximum, rather than minimum, parking standards associated with new developments and developers can negotiate to secure adequate accessibility to sites by all modes, but stringent allocations can lead to parking pressures on surrounding roads.

Financing requirements

Providing new or additional on-street parking will incur up-front planning costs associated with surveys, consultation with local residents and businesses, and scheme design. There will also be construction, signing and marking costs, and on-going maintenance and enforcement costs. In addition to this, any new off-street parking will have substantial land costs.

When time, price or occupant-related restrictions are applied to on/off street spaces, the financial commitment needed to operate these spaces can be substantial due to technological requirements. Where high technology is needed or desired for better enforcement and management of parking, the cost might exceed the income generated by parking controls (parking tickets and fines). Comparison of different parking location and type related costs for implementation, administration and technology examples can be found at VTI (2004) (http://www.vtpi.org/parking.xls).

Expected impact on key policy objectives

The following assessment of impacts on key policy objectives are made on the basis of parking location as there is insufficient evidence of the effects of changes in access/egress arrangements.

Objective	Scale of contribution	Comment
		When availability of on / off street parking is reduced, congestion might occur due to increase in search traffic. However, reduction in on-street parking could result in significant journey t ime savings depending on the enforcement of illegal on-street parking.
		By ensuring residents have parking spaces and social areas, and streets are not congested with other traffic – parked or searching for spaces.
		Reductions in parking will result in reduced air pollution, and visual intrusion. Reduced road traffic levels will have a positive impact, but the extent will be determined by the extend of traffic diversion or search traffic increase elsewhere
		When on / off street parking is restricted in certain locations, demand is satisfied on a first come first served basis, which may not coincide with priority of need. When locating permit only on-street parking, those without will be excluded, which can be problematic where no alternatives are provided. However reductions in traffic congestion will benefit both car and bus users through reduced journey times
		By banning on-street parking.
		Where reduced congestion and pollution improves environmental quality. Some motorists may divert their shopping and business activities to neighbouring areas where there are free or cheaper parking but this will depend on the attractiveness of those neighbouring areas
		Reduction in priced on street parking results in revenue loss. Providing new spaces in the form of new off-street parking require finance and revenue may be generated by pricing existing on-street parking. Traffic management arrangements around the large car parks will also require finance.

	= Weakest possible positive contribution,		= strongest possible positive contribution
	= Weakest possible negative contribution		= strongest possible negative contribution

= No contribution

Expected impact on problems

Whilst reducing the provision of on/off-street parking can reduce congestion, it can also increase traffic and emissions as drivers spend longer searching for spaces.

Contribution to alleviation of key problems

Problem	Scale of contribution	Comment
Congestion-related delay		Where search traffic is reduced by banning on street parking or by providing extra off-street parking Where alternatives to car use make modal shift feasible. Where this is not the case, congestion delay will either be severe as a result of traffic searching for a parking space, or congestion will shift to an alternative destination .
Congestion-related unreliability		Where search traffic is reduced and/or alternative modes are easier to use
Community severance		Where search traffic or queuing for car parks is reduced
Visual intrusion	or	Less on-street parking and no queues for car parks will have a positive contribution. More off-street parking at a new out of town site or multistorey will have a negative impact.*
Lack of amenity
Global warming		The net effect of multiple reductions in local air pollution may have some positive impact.
Local air pollution		Where search traffic is reduced and less traffic originated or terminated in the area.
Noise		Recutions in search traffic noise will in all likelihood be replaced by noise from freer flowing traffic unless changes to parking provision are part of a package including other traffic restraint measures.
Reduction of green space		Where new off street parking is located out of town
Damage to environmentally sensitive sites		Where new off street parking is located out of town
Poor accessibility for those without a car and those with mobility impairments		non-essential traffic is kept off the road making access by alternative means easier, and there is more and better located provision for disabled drivers. Users of alternative modes will benefit from reductions in congestion
Disproportionate disadvantaging of particular social or geographic groups		Anybody with an urgent or important need to park in a restricted area where insufficient provision is made, e.g. disabled drivers.
Number, severity and risk of accidents		Through less search traffic and parked cars
Suppression of the potential for economic activity in the area		Where parking provision is inadequate or has inappropriate access/egress arrangements, problems parking may deter economic activity.

Expected winners and losers

Defining winners and losers in respect to all possible impacts is difficult. However the beneficiaries will include businesses with high values of time, average car users and public transport users if the search traffic and egress time for parking is reduced or eliminated along arterial corridors.

Group	Winners / losers	Comment
Large scale freight and commercial traffic		Through less congestion when making deliveries; reduction on on-street for general use and extra on/off-street loading bays
Small businesses		Through reduced congestion due to search or queuing traffic
High income car-users
People with a low income
People with poor access to public transport
All existing public transport users		Where public transport is subject to less congestion related delay
People living adjacent to the area targeted		If parking problems are merely shifted to their streets
People making high value, important journeys		Time savings through reduced congestion and availability of parking spaces near to destinations.
The average car user		Suitable car parking or alternatives should be available where and when needed.

Barriers to implementation

Scale of barriers

Barrier	Scale	Comment
Legal		Legal barriers to parking location controls can vary.
Finance		Loss of revenues due to restrictions on on street parking in highly desired location such as city centres.
Political		This can be considerable where competing areas do not have co-ordinated policies
Feasibility		Space to provide long stay parking further from town centres can be a problem.

= minimal barrier,

= most significant barrier

Adverse side-effects

The most significant adverse side effect likely to result from new on-street parking is slowing down general traffic as it searches or manoeuvres for parking. Similarly, new off-street parking may generate more traffic and it is likely to cause queues at access points. This can cause congestion and be avoided when access points are designed on side roads rather than main arterials. When locating new car parks, banning on-street parking or closing down existing car parks, there will often be some opposition from local business and possibly residents. However, it should be possible to overcome this by involving these groups in parking policy development and communicating the benefits especially with past examples of success.

Other potential adverse side effects include equity and social exclusion problems if care is not taken when designing parking controls. Adequate provision must be made for those with important or urgent reasons for parking near to destinations. Additionally, supply controls should not stop people undertaking activities.

Text edited at the Institute for Transport Studies, University of Leeds, Leeds LS2 9JT