Demand impacts
The demand impacts of physical restrictions will depend on the types of implemented measures. Most changes decrease in demand for car travel and conversely increase in public transport, walking and cycling when road capacity for car use is reallocated by introduction of other transport priorities measures. This will contribute to transport policy objectives seeking to reduce congestion and associated negative impacts. However, impacts vary according to the capacity of a network at the site where a physical restriction is implemented. The nature of the network and the existing level of congestion affect the ability of traffic to change route, vary journey time and make other responses. In some cases, when capacity is reduced on one road, but there is still available capacity on other routes or other times of the day, diverted trips such as re-routing and re-timing occur, and congestion spreads out over time and space rather than becoming worse on the treated road itself.

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

= No response

Short and long run demand responses

Demand response is different in the short, medium and long term. In the first few days, there is a volatile and uncertain range of experience. It differs according to advance publicity and information, and there is a leaning period based on experience. During the first few years, after the first adjustments, there tends to be a more settled period as traffic adjusts to new conditions. In the longer run, case studies have revealed two different patterns. One pattern is a tendency for an initial traffic reduction to be offset by subsequent re-growth. In other cases where the longer run effect is not an erosion of the traffic reduction but a build-up. For example, the longer run reductions in traffic are greater than those which occur at first (Cairns et al, 1998). The demand response will vary depending on which types of measures are implemented through the plan and whether more are phased in over time. Demand responses are completed on the basis of an overall decrease in car use.

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

= No response

 *Where public transport or cycle priority measures are operated to reallocate road capacity.

**With regard to modal shift to public transport, this is unlikely to increase in the medium and long term if traffic congestion becomes unchanged or worse than before.

Supply impacts

There are some decreases in the supply of road space for car use, where road closures or changes to pedestrian area are implemented to reduce road capacity, and bus priorities or cycle lanes are implemented to reallocate road capacity. Conversely, other transport facilities increase in supply like bus lanes, pedestrian areas and so on. However, total transport spaces in some regions usually do not change in supply.

Financing requirements
The cost of physical restrictions depends on individual measures, but is usually cheaper than measures to increase road capacity. Reallocation of road capacity measures requires investment in operation of UTC systems. If access control is needed in reducing road capacity such as the closure of streets, investment and operating cost for the enforcement of access control technology may be needed. Reconstruction cost for pedestrian areas is sometimes needed to be paid.

Expected impact on key policy objectives
Physical restrictions are implemented to reduce car use and to promote using other transport. They encourage people to reduce their overall level of car traffic use in the city centre by switching from car to other modes. Also, they will contribute to a liveable, attractive and safe city centre. To see more detail on the impacts of individual measures, e.g. bus priorities, cycle lanes, traffic calming. However, if capacity is reduced on a few roads or areas but there is still capacity available on other routes, drivers may divert onto an alternative route which still has available capacity. This will reduce traffic congestion on a specific road, but not lead to an overall reduction in the level of car traffic in an urban area.

Contribution to objectives
Objective	Scale of contribution	Comment
		By reducing delays and improving reliability, depending on the scale of capacity reduction. However, by increasing diverted traffic around the area, efficiency may be reduced.
		The change of the closed roads into pedestrian areas will improve the streetscape and reduce community severence. However, the increase of diverted traffic around the area will worsen the environment.
		By reducing air and noise pollution and pressures on green space and environmentally sensitive sites when the closed roads are changed into pedestrian area. However, the increase in diverted traffic around the area may worsen the environment.
		By improving public transport conditions; benefits from reduced congestion
		By reducing traffic levels
		By freeing up potentially productive time currently lost in congestion
		The cost of road capacity allocation, and investment and operating cost for UTC systems or access control technology

Expected impact on problems
Physical restrictions would reduce car use in urban areas, hence they have the potential to contribute to the alleviation of a number of key problems.

Contribution to alleviation of key problems
Problem	Scale of contribution	Comment
Congestion-related delay		By reducing car traffic volumes and providing reliable public transport services; however there will be an increase in diverted traffic
Congestion-related unreliability		By reducing car traffic volumes and providing reliable public transport services; however there will be an increase in diverted traffic
Community severance		By reducing traffic volumes and improving an attractive pedestrian area; however there will be an increase in diverted traffic
Visual intrusion		By reducing traffic volumes; however there will be an increase in diverted traffic
Lack of amenity		Where increased walking and cycling results from the reduction of roads in a city centre there may be enhancement in the viability of local facilities
Global warming		By reducing traffic-related CO2 emissions
Local air pollution		By reducing emissions of NOx, particulates and other local pollutants; however there will be an increase in diverted traffic
Noise		By reducing traffic volumes; however there will be an increase in diverted traffic
Reduction of green space		By reducing pressure for new road building and city expansion
Damage to environmentally sensitive sites		By reducing traffic volumes
Poor accessibility for those without a car and those with mobility impairments		By enhancing the reliability of public transport and by discouraging car-oriented development in a city centre
Disproportionate disadvantaging of particular social or geographic groups		By enhancing the reliability of public transport and reducing traffic levels
Number, severity and risk of accidents		By reducing traffic volumes and/or improving a pedestrian area; however there will be an increase in diverted traffic
Suppression of the potential for economic activity in the area		By improving the efficiency of the local road network through reduced congestion

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

= No contribution

Expected winners and losers
One would not expect everybody to benefit equally from any transport measure. Indeed, those who use priority transport modes should benefit from reduced congestion. However, unless effective measures of parking control and/or public transport are introduced there can be some losers through increased traffic congestion.

Winners and losers
Group	Scale of contribution	Comment
Large scale freight and commercial traffic		Where reduction of road capacity results in increase traffic congestion on routes used by freight vehicles, reducing utilization of freight vehicles making high value journeys.
Small businesses		Where these are both reduced car use and replacement of pedestrian area encourages use of local amenities, but where reduction of road capacity results in increased traffic congestion on routes used by small businesses.
High income car-users		High income associated with high value of time and thus continued car use for high value journeys. These journeys will benefit from reduced congestion, but will disbenefit from increased congestion.
People with a low income		May benefit from reduced congestion, but not solve problems associated with low income car users
People with poor access to public transport		Where car use is discouraged they may suffer reduced accessibility.
All existing public transport users		Reduced congestion and priority measures of public transport will improve public transport reliability. In addition, where increased demand for alternatives results in increased quality and volume of service.
People living adjacent to the area target		Where increased congestion on the routes of the capacity reduced or reallocated for car use, but where priority measures of public transport will improve service of public transport.
People making high value, important journeys		These journeys will have higher priority than others, and may continue to be made by car.
The average car users		Where they may benefit from reduced congestion.

	= weakest possible benefit,		= strongest benefit
	= weakest possible disbenefet,		= strongest possible disbenefit

= neither wins nor loses

Barriers to implementation

Scale of barriers
Barrier	Scale	Comment
Legal	-	There are no obvious legal barriers to the implementation of physical restrictions.
Finance		Physical restrictions can be implemented with low costs but UTC systems and access control system are sometimes required.
Political		Reduction of road capacity for general traffic is likely to give rise to protests from local car users. This is likely to be highly related to public acceptance from car users.
Feasibility		The nature of the network and/or urban fabric is the key feasibility issue.

= minimal barrier,

= most significant barrier