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PRIMAVERA Final Report

Ken Fox, Peter Franklin and Frank Montgomery

Public Transport Priority, Queue Management and Traffic Calming


Brief description of the project

PRIMAVERA's aim was to develop co-operative strategies that combine queue management, public transport priority and traffic calming methods on urban arterial roads. Telematics enabled us to collect and influence both traffic flows and vehicle speeds on urban arterial roads. Traffic flows on the arterial and surrounding network can be collected automatically and passed to computers which rapidly calculated signal plans to minimise the overall travel time. Public transport vehicle location systems can also be used to send data to these computers to let them adjust the signal plans to ensure that public transport vehicles got priority when they pass through intersections. If it is important that vehicles obey a speed limit, vehicle speeds can be detected and speeding vehicles warned to slow down via a VMS. This advice can be enforced using speed cameras.

These methods can conflict with one another. Giving priority to public transport might cause severe disruption to other vehicles. Slowing vehicles down appears to be in direct opposition to schemes to reduce vehicle delay. However, it was possible to design schemes that use these methods in a co-operative way. Making vehicles move with similar speeds can produce well behaved platoons that are more effectively controlled. Speeding the progress of public transport vehicles can also help private traffic.

Objectives of the project

PRIMAVERA's main objectives were to:

Description of work done

Reviews of the state-of-the-art in ATT traffic control for queue management, public transport priority and traffic calming have been produced and are available as Deliverable Number 1, 2, Deliverable Number 3 and Deliverable Number 6.

An interface program has been produced to link the Italian simulation model NEMIS to the UK SCOOT system, allowing them to interact. Simulations have been carried out, using the appropriate interface, of the best strategies to find out their effects more accurately. These simulations suggest that synergy can be produced by combining appropriate strategy elements with significant reductions in travel time, vehicle operating costs, pollution emissions and accident rates being achieved.

The Italian SPOT UTC system and the UK SCOOT UTC system have been improved to let them carry out the most promising of the new ATT strategies. This includes the incorporation of a new inexpensive bus priority method.

An evaluation framework has been developed to allow consistent appraisal of both the simulations and the field trials and to allow comparisons with other DRIVE projects. This has been used to help draw up guidelines for other project's evaluation plans.

The SCOOT UTC system has been installed at the field trial site in Leeds at no cost to the project. Extra funding was obtained from the UK DOT to install the SPOT units in Leeds, along with special bus detection equipment, a speed violation camera and a VMS system. The Leeds bus operators have also purchased and installed the electronic tags for their fleet of buses. The UK EPSRC has also funded a project to look at the transferability of the PRIMAVERA techniques to other sites.

Permission was obtained to use the modified SPOT UTC system during the UK field trials. The SPOT system has been installed at ten intersections in Leeds and at seven intersections in Turin. An interface between the Italian SPOT system and UK signal controllers has been successfully developed and implemented. Permission was obtained from Turin City to use the AVM and UTC systems. All the trials in Leeds and Turin have been completed.

Main achievements

The main achievement of the project was the demonstration by simulation and field trials, that it is possible to achieve synergy by combining appropriate strategy elements.

Dissemination of information

Numerous papers have been published and presented detailing the project's results. Press coverage has also helped disseminate the results to a wide audience. The project has also put some of its deliverables onto the World Wide Web to allow access to anyone on the Internet.

Validation and user acceptance

Extensive data collection during field trials has ensured that the simulation results have been validated. These field trials have involved all the users of the project end products, including the general public, local authorities, traffic engineers and public transport operators.

Contribution to the wider programme and domain objectives

The simulations and initial field trial results indicate that the new integrated ATT strategies developed by PRIMAVERA are likely to produce significant benefits, ie. improved safety, greater efficiency and reduced damage to the environment on urban arterial roads and surrounding road networks. The project has also contributed to the Area and Topic Group meetings at Concertation Meetings and been active in a number of Evaluation Task Forces.

Consequences for the Fourth Framework Programme

The PRIMAVERA results have shown the added benefits that can be obtained by integrating different ATT applications. These methods need to be taken further to include possible integration with other applications and to test the transferability of the results to other sites in Europe.

Results and Exploitation plans

The major results which will be exploited are new improved versions of the SPOT and SCOOT UTC systems, the SCOOT-NEMIS simulation test bed, the TIRIS based bus detection scheme and the benefits of using an integrated approach for strategy development on urban arterials.


The overall objectives of the project were to:
  1. review state-of-the-art ATT traffic control and management techniques for:
  2. develop means of integrating the above techniques with one another to ensure cooperation between them, and provide also for integration with existing traffic control, public transport and environmental protection measures;
  3. simulate these integrated ATT strategies on arterial corridors with differing operating conditions in two medium sized cities to test and, as necessary, enhance their performance;
  4. conduct and evaluate field trials of the most promising integrated ATT strategies in those same cities;
  5. produce recommendations for the selection of the most appropriate integrated ATT strategies for a range of types of urban corridor, and for their implementation in differing traffic control environments;
  6. implement and analyse the field trials in Leeds and Turin.
All these objectives have been achieved.



Traffic signals in a network may be coordinated by using either fixed time plans, developed off-line using computer programs such as TRANSYT or by using real time adaptive control with systems such as SCOOT or SPOT. Within the DRIVE context, only adaptive control systems satisfy the required ATT objectives. These systems work by using information collected from detectors on street to estimate flows along links in the network. This flow data is processed by a computer which uses it to calculate appropriate traffic signal settings to achieve a set of objectives. These objectives can take many forms, typically they try to minimise stops and delay or perhaps try and give priority to public transport vehicles. Hence the traffic signals adapt in real time according to the actual flows of vehicles in the network. The current systems are far from being perfect. In PRIMAVERA the existing real time systems SCOOT and SPOT were improved so that they can implement new algorithms and their models of the network were also improved so that they represented reality more accurately.

In the field of congestion management, it has increasingly been realised that computer based traffic control systems which rely on forward progression are inadequate in highly saturated conditions, because queues form which can disrupt upstream conditions and render forward progression infeasible. To overcome this, techniques for managing upstream queues, to ensure that they do not disrupt other movements, and for regulating, or gating, the input flows, have been developed. The literature includes a range of techniques applied in cities such as Athens, Bangkok, Paris, Graz, London, New York, Southampton and Turin. The main benefits arise in reductions in delay for counter-peak and crossing traffic. Such procedures are now available in the traffic signal control methodologies of several EC countries, but no consistent guidelines have been developed for their use. In most cases, these procedures operate in fixed time, but recent research has developed a real time gating technique based on parameters such as upstream flow, downstream occupancy and the extent of downstream queue storage space. Such real time techniques are important in treating highly volatile conditions which arise in over saturation, and in responding to incidents. Neither type of technique has yet been effectively integrated into the area wide traffic control strategies applied in city centres. In particular, such integration should permit morning peak demand on the centre to be regulated to ensure that it continues to operate in under-saturated conditions. In the evening peak the problem is more complex, since gating to ensure efficient operation of the radials can exacerbate city centre congestion. A range of fixed time and dynamic gating techniques in conjunction with the existing traffic responsive signal control strategies in operation in the case study cities were tested.

State-of-the-art Reviews

The project started with a review of current techniques of queue management, both those in actual use and those in development or at the theoretical stage. This review was carried out by means of both an extensive review of the literature, and by direct or telephone interviews of relevant experienced UTC staff.

 In the field of public transport priority, extensive use is made of priority lanes, and their operation is well understood. However, they lack flexibility in traffic control, and may be counterproductive in their impact on the pedestrian environment. An alternative approach involves selective detection of priority vehicles, which may, or may not be, specially equipped. This approach provides for greater flexibility, and was tested as part of the range of techniques considered. A third approach involves modification of existing signal control strategies to provide greater weighting to those routes which have higher flows of priority vehicles. This again is an approach which is more flexible, although it may be disruptive to routes which cross the case study corridor. Finally, there is the approach of using gating techniques with priority for public transport. Most of these have been applied as part of motorway access control, but there are a few references in the literature to their use on urban arterials. The first three of these approaches are already in widespread use in Europe, and will be further developed as part of an overall strategy of public transport enhancement in DRIVE II. In our project, we tested the full range of these methods, by simulating their incorporation into existing signal control strategies. However, it was necessary to develop them further by considering their interaction with the gating techniques outlined above. It will be clear that gating could be disruptive to public transport unless it took place on approaches not used by public transport or it enabled public transport to bypass the resulting queues. Opportunities for these alternative ways of integrating the two approaches were evaluated. The first stage in this area was to produce a review of the current state of the art in public transport priority, including both physical measures (busways, bus lanes etc) and techniques involving priority at traffic signals (biased offsets, stream weighting, selective vehicle detection etc).
TIRIS unit
TIRIS unit
Implementation of public transport priority measures would either be via traffic signals controlled by either SPOT or SCOOT. The former already had the capability to give priority with and without the use of SVD: the latter did not have the capability initially, but it was developed during the project to enable this. This involved the use of a new low cost transponder called TIRIS, which was used as an electronic tag to identify buses. The consortium built on these developments to produce an enhanced version of SCOOT for use in the field trials.

In the field of traffic calming, many of the developments have been in physical redesign of minor roads in residential and shopping areas. To an extent, these measures have aggravated conditions on the main radials, by transferring traffic back to them. More recently, attention has switched to those main urban roads, from which it is difficult to divert traffic. Traffic calming techniques have been developed which concentrate on keeping traffic moving, so that queues, and their resulting emissions, are not formed, while ensuring that traffic moves slowly, thus avoiding undue risk to pedestrians and other road users. Again, most of the measures have been physical, but signal control techniques have also been developed, in which platoons of traffic are formed and allowed to pass slowly through the environmentally sensitive area, with sufficient headway between them to enable pedestrians to cross. These approaches are still at a conceptual stage, and have yet to be tested in practice. In particular, they have only been simulated in fixed time operation, while in practice they will need to perform effectively under varying conditions and in response to incidents. As a result, little is known of their actual impact on the environment, or of road users' reactions to them. Moreover, it is possible that such signal control techniques could conflict with the need to provide priority to public transport, or to gate other traffic. The project has both tested these platooning techniques further, and investigated the potential conflicts between them and the related techniques for congestion management and for public transport priority.

A comprehensive review of traffic calming techniques introduced throughout Europe has been carried out by HETS with assistance from ITS, with the knowledge that these are much more advanced in some parts of the EC than others. This report forms Deliverable No. 3.

Traffic calming measures on both Dewsbury Road and the adjacent residential areas have been developed. Emphasis was given to control using traffic signals with only minor physical modifications on the arterial. A speed violation camera has been installed on the Dewsbury Road, combined with a VMS system to warn drivers if they are travelling too fast. If they fail to heed the warning given by the sign then the camera takes a picture of the vehicle and the driver is prosecuted.


Extensive surveys have been carried out at the field trial sites in both Leeds and Turin, in preparation for the field trials and to calibrate the simulation models. Data collected has included physical characteristics, turning counts at junctions, link counts, pedestrian surveys, parking surveys, queue length surveys, journey times, O/D surveys, public transport usage, accident statistics and land use surveys. Full details are given in Deliverable No. 4.

SPOT and SCOOT modifications

Following extensive development work and testing, the Italian SPOT system and the UK SCOOT system have been modified to let them carry out the most promising of the new ATT strategies.

As an example, the SPOT system has been modified to implement a new gating strategy, which we have called auto-gating. Under a fixed time plan, unexpected traffic conditions can easily result in queues that cause excessive disruption when they begin to block upstream junctions. Recent approaches have tried to solve this problem by using a gating action to store vehicles upstream of a critical bottleneck, in a pre-determined section of road with plenty of storage capacity. Auto-gating or metering is a new form of gating whereby each link stores vehicles without blocking-back. This is achieved by funnelling the green times according to the downstream queues or space left.

A new queue evolution model, called the horizontal queue evolution model, presented in Primavera Deliverable 8, is used by the SPOT optimisation algorithm to forecast the evolution of the downstream queue as a function of the releases provided by different traffic light control strategies. This, together with information about the storage capacity of downstream approaches, permits the system to detect oversaturation conditions and to react through a gating action. Other methods of implementing auto-gating strategies with both SPOT and SCOOT have also been developed.

The SCOOT-NEMIS Interface

An interface program has been produced to link the Italian simulation model NEMIS to the UK SCOOT system, allowing them to interact. This has been achieved by two Italian engineers on secondment from MIZAR working closely with staff from the Leeds UTC centre.

The interface package is installed on a MS-DOS PC connected by a serial line with the NEMIS computer and by another serial line with the WYHETS SCOOT system located in Leeds as shown in the following diagram.
The UTC System - NEMIS Interface
The UTC System - NEMIS interface
An arrangement as depicted here is suitable to enable simulation of a portion of the WYHETS SCOOT system (Dewsbury Road) while driving the rest of the area on line. The SCOOT system was configured complete with data for the whole area including Dewsbury Road. The NEMIS package was configured with Dewsbury Road region data only.

The SCOOT system computer is a FERRANTI 700 industrial computer, the hardware interface provided by the SCOOT computer is a standard RS232 serial interface working at 1200 baud. The NEMIS computer is a 486 computer working at 33MHz under the OS/2 operating system, the hardware interface is a RS232 working at 9600 baud or 4800 baud. The interface computer is a 386/40MHz MS-DOS machine with two RS232 serial ports. The software interface package is based on the FRONTEND package produced by MIZAR currently used to interface the NEMIS package with a network of SPOT units.

The FRONTEND package software, written in the C language, is able to simulate a multitasking operating system and can communicate on several serial ports at the same time and with different speeds. The NEMIS software package is written in the FORTRAN language.

For these purposes NEMIS was able to receive, in real time, control strings for the traffic lights and to send back measures of counting sensors located on the network in the format required by the SCOOT system.


An evaluation framework has been developed, following CORD guidelines, to allow consistent appraisal of both the simulations and the field trials and to allow comparisons with other DRIVE projects. The importance of safety evaluation was highlighted and this resulted in the recommendation that conflict studies be used during the field trials.

A standard set of impact parameters were used. The expected benefits on each of these impacts are given in Table 1 below. Table 2 shows how each of these impacts were measured during the field trials. Full details of the evaluation framework can be found in Deliverable No. 11. This includes a full statistical analysis giving the likely sample size required to measure the expected benefits and a detailed field trial plan for each city.
Table 1: Expected Benefits from Integrated Strategy
Impact Variable Expected Benefit
Journey Time Reduction in overall journey time or maintained journey time with reduced variability. Benefits expected from generally more controlled speeds through the system.
Vehicle Operating Cost Reduced operating costs gained from fewer oversaturated junctions and reduced number of stops.
Comfort Increased comfort as reflected in fewer (unscheduled) stops and benefits from reduced congestion.
Safety Increased safety levels as a benefit of lower and more controlled speeds of vehicles.
Air and Noise Pollution Reduced estimated pollution levels as a benefit of reduced congestion, fewer unscheduled stops and controlled speeds through the system.
Crossing delay, Uncertainty, Visual Intrusion and Severance Reduced levels in each of these impact variables as a benefit of reduced congestion, lower and more controlled vehicle speeds.
Stress Reduced driver stress as a benefit of reduced congestion and more controlled speeds. Reduced resident stress as a benefit of reduced and controlled speeds, reduced estimated noise/pollution and reduced crossing delays.
Traffic Flows Traffic flows may be seen to increase overall as more vehicles move more efficiently through the system. However this should not occur at the cost of other impact variables such as journey time.
Vehicle Occupancy Whilst little or no change may be expected in car occupancy, bus occupancy may be expected to increase as a response to the benefits of PT/ATT measures.
Table 2: Measuring Implemented Strategy Impacts
Journey Time Vehicle Category (total 5) - cyclist, car, bus, light commercial, heavy commercial
Pedestrian: people category age/ability
Before study - 12 days, 193 runs by Moving Observer. 16 routes surveyed on 1 day. Hours 0800 - 0900, 1500 - 1600, 1700- 1800. 6 runs/hr each direction. After study the same + licence plate matching. Extra information available from Bus Survey. Minutes
Vehicle Operating Cost Vehicle Category (excluding cyclist) - car, bus, light commercial, heavy commercial Not surveyed in before study. Questionnaire to drivers/bus operators 
  • COBA
  • No of stops data as surrogate
Comfort Bus/car by people category: age/ability Not surveyed in before study. Will use "number of stops" data as a surrogate Multicriteria Form (MCF) or No of Stops
Safety May be too small to disag. by people cat. Severity - slight/serious/fatal Before study - all accidents in study area 1/1/87 to 1/1/92
After study - Conflict analysis
No and severity of conflicts.
Air and Noise Pollution Residents, Pedestrian, Cyclist Groups Not to be surveyed in the field - use Simulation Study (NEMIS) MCF
Crossing Delay People categories age/ability/visiting Complete pedestrian survey carried out for before study.
Simulation + small field surveys for after study.
Minutes or MCF
Stress Residents, Pedestrians: age/ability/visiting
Drivers: vehicle category
Questionnaires to resident categories. Could use traffic density, noise and pollution as estimates (waiting time / traffic speed / traffic flow for residents) MCF
Traffic Flows Vehicle category Before study as follows:
ATC's - 11 sites, both directions, 15 mins, 1 month (March 1992)
MCC's + Junction. 1 weekday. 0700-1000, 1500-1800. 15 mins (information collected for 7 vehicle types)
Subsid. MCC's on minor roads. Left/right turn 0700-1000, 1500-1800. 1 weekday. 15 mins (3 vehicle types collected)
All before surveys - TUES/WED/THURS 3/92. After survey, same data (June-Oct 1994) + Extra bus information.
Total vehicles otherwise MCF
Vehicle Occupancy Cars/Buses Not surveyed in before study - Use field survey People Numbers
Scheme Cost - - CBA/£/ECU

Both a Cost-Benefit approach and a Multi-Criteria method have been used to assess the simulations. In the Cost Benefit Analysis (CBA) monetary values have to be given to each impact evaluated. The rates used are those given in the DRIVE I EVA manual, they are as follows:
Table 3 : The cost of each impact used in the CBA
Impact Cost
Travel Time (UK) 14.26 ECU/person hour
Travel Time (Italy) 18.28 ECU/person hour
Fuel Consumption 0.36 ECU/l
CO Emissions 3 ECU/ton
NOx Emissions 443 ECU/ton
Hydrocarbon Emissions 348 ECU/ton
Fatal Casualty 744,177 ECU
Serious Casualty 105,593 ECU
Slight Casualty 7,080 ECU

For the Multi-Criteria Analysis (MCA) two different sets of weights were used, as shown in Table 4. The analysis has been carried out using the MASCOT program, which comes with three sets of weights built-in that reflect the opinions of the values of "Official", "Environmental" and "Commercial" groups. This set of weights has been supplemented by some additional values for impacts not originally considered. As the results of the "Commercial" weights are very similar to those using the "Official" weights, only the "Official" and "Environmental" weights are considered here.
Table 4 : Weights and targets used for the MCA
Impact Units Target %change Official Weights Environmental Weights
Car travel time saving k veh s -15 5.5455 3.0248
Bus travel time saving k veh s -5 138.6388 106.645
Travel time sd reduction k veh s -15 2.7728 1.5124
Bus time sd reduction k veh s -10 69.3194 53.3225
Stops k -10 0 100
Speed sd m/s -1 0 -0.3
Fuel consumption saving k litres -5 360 3600
NOx emissions kg -10 -0.443 -4.43
HC emissions kg -10 -0.348 -3.48
CO emissions kg -10 -0.003 -0.03
Visual intrusion by queues veh -10 10 15
Mean speed m/s 0 0 -10
Excessive speed time k s -5 0 50
Fatal casualty reduction Casualties -5 744177 1284910
Serious casualty reduction Casualties -5 105593 211186
Slight casualty reduction Casualties -5 7080 12390


A NEMIS model was developed and calibrated for all the proposed test sites. Four measures were used to assess whether the micro-simulation model was accurately producing the observed behaviour, as surveyed on-street. Care was taken to ensure that none of the information in these measures had been used to construct the data files for the micro-simulation model. These four measures were: Few of the default parameters for the NEMIS model needed to be changed in order to replicate the observed behaviour. Those that did need fine-tuning included:
  1. Maximum speed for each vehicle class. The default values were 20m/s which was thought to be too high for existing traffic conditions. These values were modified to form a distribution of such speeds between 15 and 18m/s.
  2. Car-following parameters for each vehicle class. The default parameters were for fast, short vehicles. The parameters of one of the vehicle classes were modified to model the behaviour of a slower, longer vehicle. This modification better represented the mixture of vehicle types using the traffic network. The parameters used for each vehicle class have been extensively validated during the development of NEMIS. Further validation has recently been carried out to ensure that these parameters are still applicable.
  3. Minimum speed during acceleration and deceleration for each vehicle class. The default parameters were too abrupt. Vehicles tended to travel at high speeds when approaching the back of a queue and then abruptly slow down. A more gentle deceleration profile was found to better reproduce observed behaviour.
The SCOOT and SPOT systems were also calibrated to the NEMIS models. Using the facilities offered by the appropriate interface it is possible to have the micro-simulation package mimic the on street traffic. What is required before the use of such a facility is to ensure that both the micro-simulation model and the UTC system have the same representation of the traffic in the system. Simulations have been carried out, using the appropriate interface, of the best strategies to find out their effects more accurately. The simulation results are commercially sensitive as they allow a direct comparison between the SCOOT and SPOT UTC systems, which is not an aim of the project. Therefore in this report only the SPOT based strategy results from Leeds are presented.
The Dewsbury Road Test Site
Dewsbury Road Test Site
A map showing the location of each signalised junction on the Dewsbury Road can be seen in Figure 1. The strategies that have been tested by simulation are described below. The strategy components are listed in the Table 5 below, together with a short abbreviation that will be used in the rest of the report to refer to the strategy.
Table 5 : The strategy components used at the Dewsbury Road test site
Strategy code Strategy name
Q Horizontal Queue Model
A1 Auto-gating 1 - The MX strategy
A2 Auto-gating 2 - Local Feedback Control
B Bus priority with TIRIS
S Speed Advice
This strategy improves the model within the SPOT system so that queue lengths of traffic are estimated accurately. As well as improving the overall performance of the UTC system this also allows strategies such as the auto-gating strategies, to be implemented as they need an accurate estimate of the amount of space available on each link to store queues. Gating stores vehicles upstream of a critical bottleneck, in a pre-determined section of road with plenty of storage capacity. Auto-gating or metering is a new form of gating whereby each link stores vehicles without blocking-back. This is achieved by funnelling the green times according to the downstream queues or space left. These methods involve the calculation of an upper limit to the total length of green time to be allotted to a link. This value is then used to overwrite temporarily the maximum green time for the stage which is green to the link; in cases where the link receives green time in more than one (consecutive) stage, the upper limit of green time is distributed between the relevant stages. If information on the approach of a bus at a set of signals is available then this information can be used by the SCOOT or SPOT optimisers in order to benefit buses. This benefit may take three different forms:
  1. prevent an early termination of the stage which benefits the bus;
  2. extend the stage which benefits the bus;
  3. recall early the stage which benefits the bus.
Bus priority using TIRIS
Bus Priority with TIRIS
The consortium decided to develop and install a low cost bus priority system based on TIRIS transponders as part of the field trials in Leeds. The core of the system is a small TIRIS transponder or tag that can be attached to a bus. To interrogate the tag, a reader at the roadside sends out a radio signal to the transponder via an antenna embedded in the road. The signal carries enough energy to charge up the passive (battery free) transponder. The transponder then returns a signal that carries the data that it is storing. This data is a unique, factory programmed identifier. Leeds City Council obtained funding and installed the necessary loop detectors and TIRIS readers at four junctions on the Dewsbury Road trial site. The main bus operators purchased and installed the TIRIS transponders on their fleets of buses at their own expense. A single TIRIS transponder costs approximately £25. A TIRIS reader unit costs approximately £1500 to install at the roadside. A TIRIS loop antenna costs approximately £200 to embed in the road and connect up to the reader unit. This TIRIS transponder based system therefore provides a highly cost effective way of giving priority to public transport.
The VMS and speed camera
The VMS sign and Speed Camera
The installation of a speed camera on the southern section of Dewsbury Road, provides a mechanism for enforcing slower progression speeds. This was combined with a VMS sign warning drivers if they were travelling too fast to slow down. This VMS sign is a key part of the strategies, its aim being to reduce the number of speeding vehicles and to reduce the variability in vehicle speeds so that more compact platoons of vehicles are produced which can be more easily controlled by the new queue management strategies. In the NEMIS model it has been assumed that this mechanism will be successful in limiting the maximum speeds of the vehicles.
The base environment against which all the SPOT based integrated strategies are tested is the existing road network with signals controlled by the standard SPOT system. This allows the new strategies to be tested against the current state-of-the-art system. The key to the strategy abbreviations used in the following tables and figures can be found in Table 5.

Table 6 contains the % change in the impact over the base case. The travel times of the bus services given priority treatment (Bus TT) are also shown.
Table 6 : % changes in Network Impacts over standard SPOT - AM Peak
Impact Q+S Q+B B+S Q+B+S
Mean Speed (m/s) 2.27 1.08 2.49 3.06
Speeding Time (s) -8.24 0.91 -7.94 -8.18
Blocking Back (s) 5.39 17.22 32.37 6.74
Stops (veh) -1.67 -0.73 -2.46 -1.64
Delays (s) -1.13 -1.28 -2.45 -4.33
Travel Time (s) -2.26 -1.22 -2.44 -2.95
Fuel Consumption (l) -0.79 -0.38 -1.06 -1.02
CO Emissions (g) -1.81 -1.17 -2.40 -2.66
NOx Emissions (g) -1.04 -0.78 -1.54 -1.76
HC Emissions (g) -1.68 -1.08 -2.01 -2.38
Bus Travel Time (s) -2.10 -1.21 -1.50 -1.66
Bus Time Route 2 (s) -2.23 -4.32 -2.96 -2.75
Bus Time Route 24 (s) 0.38 1.46 2.51 -1.85
Bus Time Route 46 (s) -3.07 -2.83 -1.49 -2.07

Table 7 indicates the results of the CBA. All values refer to the two hour AM peak data collection period. All the monetary values are in ECU. The rates used for the CBA can be found in Table 3. For the SPOT based strategies in the AM Peak, the integrated strategy containing the Horizontal Queue Model, bus detection with TIRIS and Speed Advice using VMS is easily the most beneficial integrated strategy. Giving priority to buses always improves a strategy when combined with other components.
Table 7 : SPOT based strategies for the AM Peak - Leeds
Strategy % Benefit over standard SPOT
B 3.28
Q + B + S 1.88
Q + S 1.69
B + S 1.63
Q + B 1.00
Q 0.41
S -1.17
A1 -1.35
A2 -2.47

The travel time figures dominate the costs associated with each strategy. Typically they are about ten times larger than the accident costs, twenty times larger than the fuel costs and a thousand times larger than the pollution emission costs. The CBA will therefore favour strategies which reduce travel time, with little regard for environmental or safety factors. Safety is a problem on the Dewsbury Road, having an accident rate of nearly double the national average for roads of its type. The CBA does not adequately reflect any improvements in safety. For this reason, the MCA is preferred.

A multi-criteria analysis has been carried out using the MASCOT program. This program comes with three sets of weights built-in that reflect the opinions of the values of "Official", "Environmental" and "Commercial" groups. This set of weights has been supplemented by some additional values for impacts not originally considered. As the results of the "Commercial" weights are very similar to those using the "Official" weights, only the "Official" weights are considered here. The weights and targets used can be found in Table 4.
MCA - SPOT based strategies
MCA of the SPOT based strategies
For each integrated strategy three scores are obtained that relate to each of the three DRIVE goals of Safety, Efficiency and the Environment. These three scores can define a point on a three dimensional graph whose axes are the three DRIVE goals. By plotting each strategy in this way it becomes relatively easy to see the effects of integrating strategy components and to isolate families of strategies that have similar consequences. To aid strategy recognition, all the individual strategies are represented by a hollow symbol and all the integrated strategies by a solid or filled symbol.

For the SPOT based strategies the Q+B+S strategy comes out on top when using the "Environmental" weights and second with the "Official" weights. There is a cluster of strategies which are all good on safety, efficiency and the environment, these being Q+S, B+S and Q+B+S. For all the strategies, integration with Speed Advice improves safety without adversely affecting efficiency or the environment. Integration with bus priority does not have much effect. A sensitivity analysis has been carried out which reveals that it is very difficult to remove Q+B+S from its top position by changing the weights. The most likely change is to reduce the excessive speed weight by a factor of three, which puts the B strategy on top. Changes in scores can also change the rankings, however within the uncertainties associated with each score it is only possible to get either Q+S or B+S to replace Q+B+S as the top strategy.

Field Trials

VMS Sign
The VMS Sign
Full details of the field trial implementation and data collection described in Deliverable 13. Preliminary analysis of results are described in Deliverable 14. The best strategy using each UTC system available at each site, according to the simulation results, has been trialed on the test sites. The strategies for each city were as follows:


Turin The surveys were scheduled to take place with the network operating under different conditions as follows:
  1. Baseline conditions, Leeds and Turin
  2. SPOT operating alone, Leeds
  3. SPOT operating with the strategies devised for PRIMAVERA, Leeds and Turin
  4. SCOOT operating alone, Leeds
  5. SCOOT operating with the strategies devised for PRIMAVERA, Leeds
Leeds Field Trials. In Leeds five types of surveys were carried out between May and December 1994 as follows:
Leeds field trial data collection
The Leeds Field Trial Data Collection

The main improvements deduced due to adoption of the PRIMAVERA strategies in Leeds are:

Speed Profile at the VMS
Turin Field Trials. Surveys were carried out in Turin between October 1994 and July 1995 as follows: Improvements produced from the adoption of the control strategy devised for PRIMAVERA in Turin can be summarised as follows:


The field trial results have shown that the adoption of integrated PRIMAVERA strategies on urban arterial roads can produce some significant improvements. Journey times for private vehicles can be reduced as can journey time variability. Priority can be given to public transport resulting in reduced journey times, delay and journey time variability. ATT traffic calming, using either a variable message sign and a speed enforcement camera or optimum speed indicators on the road-side, is succeeding in reducing the number of vehicles travelling at excessive speed and is resulting in less variability in vehicle speeds. This produces more compact platoons of vehicles which are more easily controlled by new queue management strategies.

Reviews of the current state of the art in Queue Management techniques, Public Transport priority techniques and Traffic Calming techniques have been produced.

The consortium decided to develop and install a low cost bus priority system based on TIRIS transponders as part of the field trials in Leeds. Leeds City Council obtained funding and installed the necessary loop detectors and TIRIS readers at four junctions on the Dewsbury Road. The main bus operators have installed the TIRIS transponders on their fleets of buses at their own expense. The system has performed successfully during the Leeds field trials.

Funding was obtained and the VMS equipment and an automatic speed violation camera were installed on Dewsbury Road, Leeds. The system has performed successfully during the Leeds field trials.

The SCOOT UTC system has been successfully interfaced with the NEMIS simulation model and tested satisfactorily. Enhancements have been made to the SCOOT software to allow it to implement the new queue management and bus priority strategies developed by PRIMAVERA. The field trial networks in Leeds and Turin have been coded into the NEMIS model and successfully calibrated against real data. Simulations of the new integrated strategies have been performed and evaluated.

The SPOT system has been modified to incorporate a new "Look Ahead Cost" to enhance recovery from saturated conditions and a new model for horizontal queue evolution has been developed for the new auto-gating strategy. It has also been modified so that it can implement other auto-gating strategies and give priority to buses via the TIRIS tagging system in Leeds. Innovative strategies for ATT traffic calming and bus stop protection have been developed and incorporated into the SPOT system. An interface between the SPOT units and UK local controllers has been successfully developed to allow SPOT to control UK signals. The new system has successfully operated during the Leeds field trials.

The report of the extensive 'before' surveys carried out in Leeds and Turin has been produced. This has been used in the model calibration. An evaluation framework has been produced that allows efficiency, safety and environmental benefits to be measured. This has been used to evaluate both the simulations and the field trials. The evaluation framework has been used by the Urban Traffic Management and Information Task Force as a basis for recommendations for other DRIVE II projects. Extensive surveys of the best SPOT based and SCOOT based strategies in Leeds have been carried out, and similar surveys for the SPOT system have been completed in Turin.

A best practice manual has been produced which gives guidelines on the design and evaluation of integrated strategies.

In their latest transport plan, Leeds City Council are recommending that the techniques developed by PRIMAVERA are used on other radial routes in the city. This reflects the close cooperation between the project and the cities.


Reference Number Title
1 Review of queue management strategies
2 Features of public transport priority systems
3 Review of traffic calming techniques
4 Description of Field Trial Sites
5 Letter from Turin City
6 Supplement to Deliverable 2
7 Implementation Specifications
8 Implementation Aspects
9 Initial Simulation Results
10 Specification of Integrated Strategies
11 Evaluation Methodology
12 Evaluation of Simulated Strategies
13 Field Trials implementation and data collection
14 Report on preliminary analysis of field trials
15 Overall evaluation of field trials and recommendations for Europe


Year Event or Publisher Title of Paper Authors Partners
1995 Traffic Engineering and Control Vol 36 No 11 Integrated ATT strategies for urban arterials: DRIVE II project PRIMAVERA Part 4: The Corso Grosseto Experiment Biora F MIZAR
1995 Traffic Engineering and Control Vol 36 No 7 Integrated ATT strategies for urban arterials: DRIVE II project PRIMAVERA Part 3: The Dewsbury Road Experiment Fox KA, Montgomery FO, Balmforth P, Franklin P, Siu YL and Heywood R ITS and HETS
1995 Traffic Engineering and Control Vol 36 No 6 Integrated ATT strategies for urban arterials: DRIVE II project PRIMAVERA. Part 2: Bus Priority in SCOOT and SPOT using TIRIS Fox KA, Montgomery FO, Shepherd SP, Smith C, Jones S and Biora F ITS, PEEK, HETS and MIZAR
1995 Traffic Engineering and Control Vol 36 No 5 Integrated ATT strategies for urban arterials: DRIVE II project PRIMAVERA Part 1: Overview Fox K, Montgomery FO, May AD ITS
1995 Fourth International Conference on the application of advanced technologies in Transportation Engineering, Capri, Italy, 27th. - 30th. June 1995 A Best Practice Manual for Innovative UTC Systems Montgomery FO, May AD, Fox KA, Biora F, Mauro V and Jones S ITS, MIZAR and HETS
1995 Fourth International Conference on the application of advanced technologies in Transportation Engineering, Capri, Italy, 27th. - 30th. June 1995 Integrated ATT strategies for Urban Arterials Montgomery FO, May AD, Fox KA, Biora F, Mauro V and Jones S ITS, MIZAR and HETS
1994 Workshop on Improvements of Energy Efficiency in Urban Transport Networks Current Experiences in Public Transport Priority and Trends Fox KA, Clark SD, Lanteri F, Biora F, Conte S ITS and MIZAR
1994 EURO XIII / OR 36 Conference. University of Strathclyde Evaluation of integrated ATT strategies for urban arterials Montgomery FO and Fox KA ITS
1994 OR Insight Volume 7, Issue 2. April-June 1994 Giving Benefit to Buses Clark SD and Pretty RL ITS
1994 CETTEC 94, St. Patrick's College, Maynooth, Ireland. 8-9 September 1994. Design of Integrated ATT Strategies for Arterial Routes Biora F, Clark SD, Fox KA and Montgomery FO MIZAR and ITS
1994 World Congress, Paris November-December 1994 PRIMAVERA: Integrated ATT strategies for urban arterials Biora F, Fox KA and Montgomery FO MIZAR and ITS
1994 World Congress, Paris November-December 1994 PRIMAVERA: A Best Practice Manual for Innovative UTC Schemes Montgomery FO and Biora F MIZAR and ITS
1993 Institute for Transport Studies - Technical Note No.s 328/329 Collection, Analysis and Interpretation of Bus Survey Data for use in a micro-simulation package. Clark SD ITS
1993 Drive Technical Days Meeting, Brussels. Primavera Project - Initial Simulation Results Clark SD and Montgomery FO ITS
1993 Universities Transport Studies Group Conference The Evaluation of Management Strategies for the Leeds Test Site Fox KA, Pretty RL, Shepherd SP and Clark SD ITS
1993 Applications of Advanced Technologies in Transportation Engineering Metering Strategies Applied to Signalized Networks Shepherd SP ITS
1992 Traffic Engineering and Control Vol 33 No 11 A Review of Queue Management Strategies Quinn DJ HETS
1992 Conference on Vehicle Navigation and Information Systems Integrated Traffic Control on Urban Arterials Bolelli A and Montgomery FO MIZAR and ITS

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