Priority network for Heavy Good Vehicles (HGV)

Summary

A recommended road network for Heavy Good Vehicles (HGV) is developed in Stuttgart, guaranteeing shorter, more efficient routes for urban HGV and protecting vulnerable urban areas from HGV-related impacts. In a selected test corridor the existing dynamic traffic control system is upgraded to guide HGV traffic to alternative routes.

Implementing sustainable mobility

Stuttgart is located in the centre of a thriving economic region with high traffic. Every day about 800,000 cars enter and leave the city. Since a complete peripheral ring road does not exist, car traffic is forced to use the limited urban road network. Although HGVs are prohibited from passing through the city and parts of the greater Stuttgart region, 6% of circulation of motorised vehicles within the city boarders are HGVs that come and go into the city or head to other parts of the region. As a result, vulnerable urban areas are negatively affected by air and noise pollution.

The measure will identified a recommended road network for HGV based on an integrated approach. The recommended road network combines aspects of urban development, transport planning, and environmental protection. Finally the existing road network was classified into segments, which are

• recommended for HGVs,
• not recommended for HGVs,
• restricted to HGVs.

To inform the truck drivers on the recommended road network for HGVs, respective information is now available on the internet via a downloadable pdf-version of the map. Leaflets are distributed in Stuttgart and the surrounding regions on the topic.

In a test-corridor the HGV traffic was directed to alternative traffic routes using dynamic traffic control strategies. This enabled the resp. authorities to analyse the HGV-related environmental impacts within concerned areas. The integration of transport management and urban and environmental planning is particularly a new and innovative aspect. In general, these two aspects are strongly linked to each other.

Further objectives are:

• Efficient operation of the urban HGV-transport by concentration on a recommended network
• Protection of sensitive urban areas from HGV-related impacts (noise, air pollution)
• Reduction of noise (-3 dB(A)) and air pollution (-10 %) based on a dynamic traffic guidance for HGV (test corridor)

Progress

The measure ‘HGV-network’ mainly deals with defining an appropriate network for HGV. It analysed which road segments of the main roard network are suitable for handling the HGV and can be combined with other network functions (e.g. the strategic network for traffic control). In addition the measure identified road segments which consider urban or environmental requirements. The analysis has resulted in the first draft of the HGV network.

This first draft has been discussed with three different stakeholder groups. The groups represent the users (e.g. chamber of commerce and industry, department for business development, representatives of outstanding companies), relevant public (e.g. citizens, local politicians, groups of interest), and the experts (local and regional).

This process took place in spring and early summer 2015 and included three events:

• Kick-off event
• Meeting with public admininstration team
• Event with participation of citizens and stakeholders

Following this consultation process a large number of measures that potentially may shift HGV to designated roads or protect sensitive areas from HGV-related impacts were analysed. Effects on route choice and traffic volumes as well as changes of air concentrations and noise levels were calculated with the chosen methodology. The final traffic assignment with the priority network for HGV was carried out with the following results:

• Total distance travelled HGV [km]:
  The difference compared between with and without the priority network is ‘- 1,5%. The share of distance travelled by HGV on the priority network rises to 6%
• Total travel times HGV [h]:
  The difference compared between with and without the priority network is ‘- 1,1%.The share of total travel times of HGV on the priority network rises to 6%

Taking into account these results the priority network for HGVs has been completed and comprises:

• priority network of the first level without restrictions
• priority network of the second level
• segments with restrictions

Finally the HGV priority map was developed showing on the front page the recommened HGV priority network and on the backside the area in which HGV through-traffic is prohibited. Additionally the map includes information on the relevant traffic signs and on points of interest. The locations of the necessary HGV related signposts were determined by using the basis of geo-referenced signage plans.

Dynamic guidance of HGVs (test corridor)

The measure analysed in a test corridor whether this approach can be recommended. Traffic volumes and the share of HGV were calculated on alternative routes during the periods of dynamic guidance. The level of the measure's acceptance was estimated based on these calculations. Traffic data were also used for modelling changes in emissions and noise levels. Travel times have beenmeasured also. In addition, operating costs for HGVs were estimated based on changes in travel times. Construction and operation of the dynamic guidance facility were funded by the municipal traffic control centre.

The test corridor was situated in the western part of the city. A federal motor highway connects the highways A8 and A81 directly with the city and the city centre. As alternatives there are three routes which are classified as municipal.

This test corridor was already equipped with variable message signs (VMS), enabling proper guidance for HGVs.

Outcomes

Recommended network for HGVs

A specific network for HGVs was determined based on the existing major road network. This recommended HGV network is of high importance for various stakeholders:

Industry and commerce: The recommended HGV-network supports the planning of commercial transport. It was developed in cooperation with industry and commerce and was disseminated via the internet and through leaflets.

Urban and environmental planning: The integrated approach offers the chance to protect vulnerable areas from HGV-related impacts. At the same time the defined HGV-routes guarantee that more functional road design will be considered in future planning processes.

Traffic control: The defined network provides a fundamental basis for meeting the requirements of an efficient and reliable commercial transport system. The technical infrastructure can be improved within the HGV-network systematically. Also the HGV network can be implemented in dynamic routing systems and is essential for further signposting.

The traffic assignment shows that already today most of the vehicle kilometers of HGV-transport are done on suitable parts of the main road network. Total distance, total travel times and total operating costs decrease by 1%. Regarding the HGV transport emissions, the decrease is even lower between 0,3% (NO₂/ NO_X emissions) and 0,6% (noise). A traffic-control effect is not to be expected just by the definition of the network, but additional measures along the network may lead to noticeable changes in the traffic flow on the respective routes.

The assignment also points up that concerning HGV transport, the aspects ‘environment’ and ‘transport’ are highly contradictory. The approach to determine the HGV network took into account this contradiction. The HGV-priority network and the associated qualitative requirements (e.g. synchronised traffic lights, design parameter) offer mostly practical significance for relevant administrative departments in Stuttgart.

The new road map of the recommended HGV network is available in a printed and a digital version. It serves as planning tool both for public authorities and private companies.

In addition, a new project with a GIS supporting documentation of traffic restrictions has been created within the administration.

Dynamic guidance of HGVs (test corridor)

A dynamic traffic control system has been used in a test corridor to guide the HGV traffic on alternative routes. This test has showed the capability and the limits of dynamic HGV guidance.

The traffic survey with dynamic guidance of HGVs has shown that only about 4.5% of HGVs could be shifted. The analysed travel times on all routes with dynamic guidance were shorter than without using the recommendation. The levels of acceptance when using the recommended route of HGV is rather low in this pilot study.