Why introduce Guided Bus?
The underlying argument for introducing guided bus systems is that they provide opportunities to implement dedicated busways where road space is in short supply and, hence, where conventional bus lanes could be impractical. This means that they are particularly well-suited to congested conditions, as they represent a means of increasing bus speeds and reliability for the minimum loss of road space to other vehicles. Two further reasons for implementing kerb guided bus systems, specifically, are that they provide opportunities to improve physical access to the bus by minimising the vertical and horizontal gaps between the bus and the kerb at the bus stop and that the physical segregation from other traffic provided by the kerbs means that it is impossible for other vehicles to block the guideway. In this way, kerb guided bus systems are 'self-enforcing', as opposed to interventions such as bus lanes Bus Priority and street running light rail which require some degree of police enforcement in order to protect the rights of way for the vehicles for which they are intended.

They also provide for considerable flexibility in operations, in that a suitably adapted bus can travel on a guideway where this is available but can also travel on any other part of the road network as required. This means that, in contrast to light rail, distributed access to the guided bus corridor can be provided easily in outer suburbs using the same vehicles. They are also very flexible in that guidance need only be provided where and when traffic conditions deem it appropriate. For example, guideways may be constructed at particular congestion 'hot spots' to allow suitably equipped buses to enter the guideway, advance to the front of a traffic queue, and then leave the guideway to re-enter the main traffic stream. This allows for incremental implementation, whereby self-contained, perhaps relatively short, sections of guideway may be constructed ready for use by suitably equipped vehicles straight away, rather than having to wait for a network of guideways to be constructed. This means that benefits can start occurring early on in the process. It also means that, as congestion becomes worse, or as it changes its location, new sections of guideway may be added relatively easily.

Short and Long Run Demand Responses
Guided bus systems provide a high quality public transport alternative to car travel so they are likely to impact on the demand for travel by car, as people switch from car to guided bus, and by other forms of public transport, as people switch from lower quality public transport services to guided bus. The attraction of public transport users from other, lower quality public transport on that, or other, corridors may, however, detract from the viability of those other services and result in a reduction in their supply. The extent to which guided bus will draw it's demand from car as opposed to from lower quality public transport services will depend on whether guided bus is viewed as being on a par with existing bus services or more closely related to a rail service. This is an important question but one on which the answer is not yet clear.

The increased physical accessibility of kerb guided bus systems will provide new travel opportunities for people who have difficulties with conventional bus services (eg, older people, disabled people, parents with buggies etc). These (?) public transport quality enhancements are also likely to generate new public transport journeys. Hence, guided bus systems will not only impact on the demand for car travel and the demand for other public transport travel, but will impact on the total demand for travel within the area.

Responses and situations outlines potential responses to the introduction of guided bus systems and the situations in which particular responses are encountered.

Response	Reduction in road traffic	Expected in situations
		Where passengers set out slightly earlier or later to fit in with the more reliable bus timetable
		Where people living away from the guided bus corridor travel by car in order to use the service.
		Where increased average bus speeds and reliability make travel to more distant destinations more attractive/feasible
	NA	NA
		Where travellers switch from car to guided bus
		Where travellers switch from other public transport, walking or cycling to guided bus
		Where reductions in non-guided bus services lead to people switching from public transport to car
		Where the main driver in a household decides they no longer need a car of their own
		Where the household decides that there are benefits from living closer to the guided bus corridor

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

= No response

Short and Long Run Demand Responses
The nature of guided bus means that it's implementation is usually phased over time, which consequently means that it's demand impacts are also phased over time. Short term impacts on public transport patronage are likely to be noticeable but may largely comprise transfers from other bus services, either in the corridor in question or immediately adjacent corridors, to the guided bus services; such transfers may involve people diverting from their previous route in order to travel on the guided bus corridor. As the system becomes more established journey-time savings and journey-time reliability may be more noticeable, facilitating some changes in people's departure times. These time-savings and reliability improvements provide a strong potential to attract car-users to guided bus, particularly where there is traffic congestion.

Response	-	1st year	2-4 years	5 years	10+ years
	-
	-
	Change job location
-	Shop elsewhere
	Compress working week
-	Trip chain
-	Work from home
-	Shop from home
	Ride share	NA	NA	NA	NA
-	Public transport
-	Walk/cycle
	-
	-

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

= No response

Supply Impacts
Guided bus systems have the effect of reallocating road space from general traffic to bus traffic at particular points in or along particular stretches of the road network. In this sense they do not actually affect the total supply of road space. However, by re-allocating space in favour of public transport in a way which minimises the loss of space for general traffic, they are an effective means of increasing the potential flow of people travelling along a particular road. Thus, in this sense they increase the capacity of the affected road.

A guided bus service will tend to replace, or represent an enhancement to, existing bus services along the corridor in question. So again in this sense they do not necessarily increase the supply of buses within the affected corridor. However, by freeing up buses and their drivers from delay due to congested traffic conditions, they allow for a more efficient use of the bus fleet and driving crew. These efficiencies may then be passed on to the travelling public in the form of cost savings or service improvements, eg increased service frequencies along the route (or along other routes via redeployment of buses and drivers); alternatively, the efficiencies may be recycled within the bus operating company, eg in the form of higher wages.

Another way in which kerb guided bus systems affect supply is via their provision of step-free access on to and off the bus. In doing this, they increase the share of physically accessible public transport services within an area and, hence, change the nature of the public transport network.

Financing requirements
Bus rapid transit systems in general, and guided bus systems in particular, will tend to be considerably less expensive, in terms of capital costs, than rail-based systems, though operating costs for bus-based and rail based systems will tend to be relatively similar. A US study showed that the capital cost of constructing dedicated busways ranged from 7m dollars per mile to 55m dollars per mile, with an average cost of approximately 13m dollars per mile (General Accounting Office, 2001). Remembering that guideways will typically only be provided at certain key points along a bus route, a guideway can have a relatively significant impact at a relatively low cost. For example, some projects involve guideways along less than 10% of the bus route. For comparison, the same study showed an average cost for constructing a light rail line of 34m dollars per mile. In contrast with guided bus, a light rail line must be provided for the full length of the route.

Expected Impact on Key Policy Objectives
The diversion of car journeys to guided bus will contribute to economic efficiency, environmental and, to a lesser extent, safety objectives, whilst the new travel opportunities will contribute towards accessibility-related objectives and towards economic growth. The attraction of public transport users from other, lower quality services will represent benefits for those people switching, but any reduction in the supply of those other services will, at least partially, offset these benefits and may detract from accessibility-related objectives and economic growth.

Whilst guided bus systems are likely to have positive equity implications, since they offer a service which can be used by all, these benefits are limited to the corridors directly served, and any corresponding reduction in bus services may disadvantage certain groups of travellers.

The positive impacts of guided bus systems depend critically on their ability to attract patronage. As noted above, if guided bus is perceived by car users as a slightly improved bus it will be unlikely to contribute significantly to key objectives and will perform much as bus priority measures do Bus Priority. If it is seen as a higher quality service approaching that of rail, its impact will be much greater.

Contribution to Objectives

Expected impact on problems
Where they attract car-users, guided bus systems have considerable potential to contribute to the alleviation of congestion-related and environmental problems; where they re-allocate road space away from the car there may also be some adverse impacts on congestion, though these should be less than in the case of light rail which requires more road space than does guided bus. In addition, there may be some adverse impacts on community severence unless stringent efforts are made to assist people to cross the guideway, eg via the use of pedestrian controlled crossing facilities. Again, impacts will depend on the extent to which it is perceived as a slightly improved bus or as a higher quality service approaching that of rail.

Problem	Scale of contribution	Comment
Congestion-related delay		By allowing the bus to avoid key areas of congestion and by transfer of car journeys to guided bus, though there may be some attraction of previously suppressed car traffic if congestion falls notably
Congestion-related unreliability		By allowing the bus to avoid key areas of congestion and by transfer of car journeys to guided bus, though there may be some attraction of previously suppressed car traffic if congestion falls notably
Community severance		Whilst guided bus systems would usually be associated with infrastructure works to improve pedestrian conditions, including provision of additional road crossings, the kerbs on the guideway represent a barrier to lateral movement
Visual intrusion		So long as design is sensitive to the surrounding environment
Lack of amenity		-
Global warming		By reducing traffic-related CO2 emissions
Local air pollution		By reducing emissions of NOx, particulates and other local pollutants from car traffic
Noise		By reducing car traffic volumes
Reduction of green space		Guideways will often be constructed on the green spaces at the edges of highways, eg grass verges or central reservations
Damage to environmentally sensitive sites		-
Poor accessibility for those without a car and those with mobility impairments		By enhancing and providing easier access to the bus system
Disproportionate disadvantaging of particular social or geographic groups		By enhancing and providing easier access to the bus system, though some may be disadvanted if bus services along corridors adjacent to the guided bus corridor become unviable and are withdrawn
Number, severity and risk of accidents		By providing the bus with safe guidance and by reducing car traffic volumes
Suppression of the potential for economic activity in the area		By improving an area’s accessibility and by improving the efficiency of the local transport network

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

= No contribution

Expected Winners and Losers

Group	Winners / losers	Comment
Large scale freight and commercial traffic		Re-allocation of road space in favour of the bus represents a loss of road space for freight and other traffic, though this may be offset if the effect of the guided bus system is to reduce congestion
Small businesses		Generation of new trips may be associated with an increase in local economic activity
High income car-users		Re-allocation of road space in favour of the bus represents a loss of road space for other traffic, though this may be offset if the effect of the guided bus system is to reduce congestion
People with a low income		People with lower incomes would tend to already be bus-users so would benefit from an improvement to bus services, though this may be eroded if the guided bus has premium fares or if it abstracts from bus services on adjacent corridors and make them less viable
People with poor access to public transport		Guided bus systems would tend to be established along existing public transport corridors
All existing public transport users		Existing public transport users along or near to the guided bus corridor will be affected in a number of different ways; some will enjoy access to faster, more reliable bus services, some may experience over-crowding on the service, some may Those people who live within easy walking distance of the guided bus corridor will enjoy an enahcned bus serviceexperience reductions in the level of competing bus services
People living adjacent to the area targeted		People who live within walking distance of the guided bus corridor will enjoy access to the improved bus services, however the reduction in public transport use on parallel routes may lead to a reduction in the level of service on those parallel routes
People making high value, important journeys		any time savings resultting from reductions in congestion will be highly valued
The average car user		To the extent that car traffic is reduced, the average car-user may enjoy some improved journey times and journey time reliability

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

= neither wins nor loses

Barriers to Implementation

Scale of Barrier

Barrier	Scale	Comment
Legal		Some form of planning approval or traffic regulations will generally be required, though usually no need for legislation or public inquiry
Finance		Total scheme costs are generally relatively low and can be phased over time
Political		Re-allocating road space away from general traffic is likely to give rise to protests from local car-owning residents, as well as from some local business and competitor bus operators without suitably equipped vehicles. Promoters of alternative technologies, such as light rail, might also be expected to be in opposition
Feasibility		May be institutional difficulties where the local highway authority is separate to the local public transport authority and/or where there are competing bus operators. May also be design and engineering issues associated with minimising any negative impacts on local access

= minimal barrier,

= most significant barrier