Executive Summa

Freeway Geometric Design for Active 

Traffic Management in Europe

OCTOBER 2010

International Technology Scanning Progr

Sponsored by:

In cooperation with:

American Association of State Highway 

and Transportation Officials

National Cooperative Highway 

Research Program

Freeway Geometric Design for Active Traffic Management in Europe 1

Introduction

Continued growth in travel on congested freeway 

corridors exceeds agencies’ abilities to provide 

sufficient solutions and alternatives based on 

traditional roadway expansion and improvement 

projects. High construction costs, constrained 

right-of-way, statutory restrictions, and environmental factors are pushing agencies to explore 

solutions such as active traffic management and 

managed lanes, which improve safety by reducing 

collisions and nonrecurring congestion and 

maximize throughput under congested conditions. 

Finding cost-effective options to mitigate recurrent 

and nonrecurrent congestion on freeway facilities is 

one of the most significant challenges State and 

regional transportation organizations face. 

 

Several countries are implementing managed 

motorway concepts to move higher traffic volumes 

on their freeways more efficiently without acquiring 

more land and constructing large-scale infrastructure projects. Managed motorway concepts 

introduce new and revised operational activities 

that place greater reliance on technology than 

traditional roadway projects. Managed motorways 

combine actively or dynamically managed operational regimes, specific infrastructure designs, and 

technology solutions. They use a range of traffic 

management measures to actively monitor the 

motorway based on real-time conditions:

n Dynamically control speeds (see figure 1). 

n Add capacity (figure 2). 

n Inform road users of conditions on the network 

(figure 3, see next page).

The objective of implementing this range of 

measures is to optimize traffic and safety performance. Examples of these measures include 

shoulder running, variable speed limits, lane 

control signals, dynamic rerouting, and the 

provision of driver information using variable 

message signs. Managed motorway concepts 

applied in Europe have been proven to reduce 

collisions, improve journey time reliability, 

and increase vehicular throughput. 

Figure 1. England: example of variable speed limit 

in Birmingham (vehicles enter the roadway from 

the left, opposing traffic is on the right, and speeds 

shown are in miles per hour).

Figure 2. Netherlands: example of shoulder running.

E x cutive Summa

Freeway Geometric Design for Active

Traffic Management in Europe
2 EXECUTIVE SUMMARY

Background

In 2006 a scan team observed that transportation 

agencies in Denmark, England, Germany, and the 

Netherlands, through the deployment of congestion management strategies, were able to optimize 

the investment in infrastructure to meet drivers’ 

needs. Strategies included speed harmonization, 

temporary shoulder use, and dynamic signing and 

rerouting. The team’s recommendations for U.S. 

implementation included promoting active traffic 

management to optimize existing infrastructure 

during recurrent and nonrecurrent congestion, 

emphasizing customer orientation, focusing on trip 

reliability, providing consistent messages to roadway users, and making operations a priority in 

planning, programming, and funding processes.

Since the 2006 scanning study, active traffic 

management concepts have been implemented in 

Washington and Minnesota and are being considered in Virginia. During these implementations, 

several geometric design-related questions were 

voiced. A scanning study was proposed to obtain 

a better appreciation for how geometric design is 

handled with active traffic management programs. 

The desk scan revealed that several European 

counties have implemented innovative geometric 

design solutions in their active traffic management 

programs. In June 2010 a team of 10 U.S. transportation professionals with expertise in planning, 

design, and operations of freeways visited 

four countries in Europe: England, Germany, 

the Netherlands, and Spain. The purpose of 

the scanning study was to examine active traffic 

management design practices used in other 

countries to improve the operational performance 

of congested freeway facilities without compromising safety. This 2010 scan built on other scans 

that focused on congestion management and 

managed lane programs.

Key Findings

Key findings from the 2010 scan include the 

following:

n Much like the United States, many European 

nations face growing traffic and congestion 

levels on their freeway networks. Several 

European highway agencies are responding 

to growing congestion by implementing active 

traffic management systems that better use 

the existing roadway footprint. In Europe, 

“managed motorways” is the term used to 

describe the traffic management measures 

implemented to improve traffic flow, enhance 

safety, and inform road users of conditions on 

the freeway network. Managed motorway 

concepts have had great success in the 

countries the scan team visited, and these 

strategies and techniques are likely to provide 

great benefit if applied in the United States.

n The European countries visited comprehensively integrate a suite of complementary 

techniques to dynamically manage traffic flow 

in response to changing volumes, speeds, and 

incidents. The result is demonstrably improved 

safety, travel time reliability, and congestion 

relief on urban motorway sections. Techniques 

that integrate roadway design with operational 

strategies include the following:

Figure 3. England: examples of variable message 

signs in Birmingham (vehicles enter the roadway 

from the left, opposing traffic is on the right, and 

speeds shown are in miles per hour).
Freeway Geometric Design for Active Traffic Management in Europe 3

 Variable speed limits, line control, and speed 

harmonization (see figures 1, 4, and 5)

 Shoulder running (figures 2 and 4) with 

emergency refuge areas (figure 6)

 Queue warning and variable messaging 

(figure 3) 

 24/7 monitoring of traffic with cameras 

and/or in-pavement sensors (both to 

detect incidents and identify when 

to reduce speed limits) (figure 7) 

 Incident management (figure 8, see 

next page) 

 Automated enforcement (see figure 9 

on next page for examples of signs) 

 Specialized algorithms for temporary 

shoulder running, variable speed limits, and/

or incident detection and management

 Ramp metering (coordinated or 

independent function)

Figure 4. Germany: example of shoulder use 

and variable speed limit from Hessen Web site 

(speeds are in kilometers per hour).1

Figure 5. Netherlands: example of variable speed 

limit (speeds are in kilometers per hour).

Figure 6. England: example of emergency refuge 

area in Birmingham (traffic travels on the left side 

on England’s roadways).

Figure 7. Netherlands: examples of surveillance 

camera and loop detectors.

Camera

Loop detectors

Source: Stau
4 EXECUTIVE SUMMARY

n Managed motorway strategies are synergistic 

and are most effective when applied in an 

integrated and dynamic system. 

n Many managed motorway concepts are 

applicable to all U.S. metro areas and 

rural high-volume freeway corridors. The 

management strategies appropriate for a 

freeway corridor evolve as the needs and 

demands of the area change. In other words, 

transportation officials should recognize that 

freeways need a continuum of operational 

and management strategies that change 

as traffic needs and demands change.

n European countries faced safety concerns 

similar to those in the United States and 

successfully addressed those concerns in 

managed motorway deployments. Managed 

motorways have contributed to substantial 

safety improvements in Europe. 

n Many European countries went through a 

paradigm shift in their design policies and 

practices by adopting risk- and performancebased approaches to making design choices 

on actively managed freeway facilities. An 

example of changed design philosophy is 

considering the dynamic operating regimes 

of a managed freeway rather than selecting 

design criteria based on a static operating 

condition. Successful active traffic management deployments require a well-planned, 

interdisciplinary collaboration of design 

with operations and enforcement. Successful 

implementation also requires the following:

Figure 8. England: examples of incident 

management in Birmingham.

Figure 9. Examples of automated enforcement signs.
Freeway Geometric Design for Active Traffic Management in Europe 5

 High-level champions who lead a culture 

change in an agency and institutionalize 

the agency’s commitment to prioritizing 

traffic management 

 Overcoming the “we never did this

before” attitude

 Funding commitments for adequate 

long-term operational maintenance

n Advancing active traffic management in 

the United States will require evolution of 

long-standing design practices, collaboration 

of design and operations disciplines, and 

advances in real-time communication 

to motorists.

Findings for Design 

n Functionality of shoulders. Representatives 

of the host highway agencies shared their 

evolving perspectives on the functionality of 

freeway shoulders. In both England and the 

Netherlands, it was noted that the utility of 

the outside shoulder to serve as a disabled 

vehicle area has diminished because of 

improvements in vehicle mechanical reliability. 

Therefore, the level of risk for not providing 

full shoulder widths may have diminished 

compared to when fundamental freeway 

design criteria were established. These types 

of considerations weigh into the host highway 

agencies’ assessment of the tradeoffs for 

continual or dynamic shoulder running. Each 

of the countries visited had a general practice 

of reducing the speed limits within freeway 

sections where shoulder width was reduced 

(both permanently and part time) to allow 

shoulder running. 

n Shoulder running (or plus lanes) with 

variable speed limits. On some motorway

segments in England, Germany, and the 

Netherlands, the shoulder is used dynamically 

to create an additional travel lane when 

conditions are appropriate. When the travel 

lane is added on the outside edge (e.g., right 

side for Germany and the Netherlands, left 

side for England), “hard shoulder running” is 

the term generally used. When the additional 

lane is on the inside edge, “plus lane” is the 

term used. Gantries that include speed and 

lane control signs are provided in these 

sections and can show a green arrow when 

the lane is available for use and a red cross 

when it is closed. The signs can also show 

the appropriate speed limit when shoulder 

running is allowed or the plus lane can be 

used. In Germany, when a paved shoulder is 

converted to a travel lane, a reduced speed 

limit of 120 kilometers per hour (km/h) 

(75 miles per hour (mi/h)) is considered 

(from a normal speed limit of 130 to 150 km/h 

(81 to 93 mi/h)). If reallocation of the roadway 

for hard shoulder running reduces lane widths 

to less than 3.5 meters (m) (11.5 feet (ft), 

a speed limit of 100 km/h (62 mi/h) is instituted. During shoulder running, the speed 

limit of the hard shoulder and the general 

travel lanes varies based on data from 

surveillance systems (loop detectors and/

or cameras). 

n Lane width. When an existing roadway cross 

section is reallocated to add a lane, existing 

lane widths may be narrowed to accommodate 

the new lane. In several locations, lane widths 

varied within the cross section, with narrower 

lanes typically on the inside (or the lane nearest the median). In some instances, no-passing 

restrictions were instituted for trucks to restrict 

them from the narrow inside lanes, harmonize 

speeds, and maintain lane control.

n Shoulder running and ramp junctions. Different approaches are considered for shoulder 

running through ramp junctions. In England, 

initial operations of shoulder running used only 

shoulder segments between ramps (i.e., the 

shoulder functioned as a lane gain or lane drop 

at each interchange). In 2009 England implemented a pilot using through-junction running 

on the M42 motorway at certain locations to 

increase capacity at key bottlenecks. 

n Lighting needs with shoulder running. 

Lighting for shoulder running sections has 

been a discussion topic in England, and over 

time the Highways Agency has found that 

continuous lighting treatments are not highly 

essential. In Germany and the Netherlands, 

continuous lighting is considered beneficial. 

n Variable speed limits, line control, and 

speed harmonization. Speed harmonization 

is introduced through the use of variable 

speed limits to improve traffic flow on 

freeway sections that experience recurrent 

congestion and protect vehicles at the back 

of congestion- or incident-related queues. 
6 EXECUTIVE SUMMARY

The speed harmonization system detects 

changes in traffic speeds and volumes along 

a corridor, and an algorithm automatically 

reduces speeds based on real-time traffic 

conditions. To ensure respect for the variable 

speed limits, communicating the reason for 

the lower speed and enforcement are essential. Representatives of the European agencies 

used the phrase “trust equals compliance” on 

several occasions to indicate that the speed 

limit needs to be reasonable and the reason 

for lower speed needs to be clear. 

n Gantry and detector spacing. The spacing 

between gantries that contain variable speed 

limit and line control signs and detectors that 

collect traffic data varies among countries. In 

Germany the national standard is 2.5 kilometers (km) (1.6 miles (mi)), but Hessen spaces 

its detectors at 1 km (0.6 mi) and gantries 

at 1 to 1.5 km (0.6 to 0.9 mi). It justifies the 

shorter spacing to collect better traffic flow 

data, provide better alternate route information, and improve system management. Other

countries use 600-m (0.37-mi) to 1,000-m 

(0.62-mi) spacing of gantries. For gantry 

spacing, both the English and the Germans 

stressed the importance of having a continuum 

of information with intervisibility of signs on 

successive gantries for the driver. 

n Emergency refuge areas. When the shoulder 

was used as a travel lane—either part time or 

permanently—emergency refuge areas were 

added. The spacing of the refuge areas 

varied by facility and country. 

n Signs. There is an ongoing debate on the 

best balance between static and variable 

message signs. One thought is that variable

message signs provide better opportunity 

to communicate with the driver, such as 

the reason for speed limit changes or the 

presence of a queue or anticipated delay 

downstream. Some suggest that all signs 

should be dynamic signs, whether electronic 

or mechanical. However, variable message 

signs are more costly and require backup 

power systems to maintain continuous 

operation during a power failure.

n Evolution in design philosophy: transition 

to a performance- or risk-based design 

approach. Representatives from England, 

Germany, and the Netherlands all emphasized 

the need to use performance- and risk-based 

methods for making design choices. 

Historically, highway design criteria have 

been developed with a static roadway in 

mind. With a dynamically operated roadway, 

the needs and solutions may be different from 

those of a static design. Performance-based 

design is an outcome-based, operationally 

focused design approach that considers the 

desired goals and objectives of the transportation facility and establishes project design 

criteria accordingly. England has developed 

a risk-based approach to innovative design 

practices, providing additional flexibility to 

design for safe operations. 

n Evolution of design criteria. Countries continuously evaluate cost-saving approaches, 

including the tradeoffs of increasing the 

spacing between gantries, detectors, and 

emergency refuge areas. In England earlier 

implementations are now considered conservative and current experience indicates that 

greater spacing may be appropriate.

Findings for Performance Measures

n Key performance measures: travel time 

reliability and safety. The key performance 

measures used in some European countries 

are improved travel time reliability while 

enhancing or maintaining safety. The active 

traffic management strategies being implemented allow a wide range of options to 

improve or maintain safety while providing 

substantive mobility benefits. 

n Other performance measures: travel speed 

and congestion. Average travel speeds for a 

roadway section have been used to quantify 

successful implementation of traffic management strategies, in addition to recognized and 

documented improvement in congestion. In 

Germany the Congestion-Free Hessen 2015 

initiative was started with the intent to ensure 

continual improvement of traffic flow. The 

vision of the initiative is that “mobility is one 

of the greatest issues for the future in Hessen. 

Both in economic and ecological terms, as 

well as with reference to social and cultural 

aspects, this task demands our full attention. 

Because for a transit state like Hessen at the 

heart of Germany and Europe, mobility and 

logistics are not only sustainable economic 
Freeway Geometric Design for Active Traffic Management in Europe 7

factors but also synonyms for a modern and 

progressive society.” 2 Hessen has experienced 

a reduction in congestion of 80 percent,3 but 

the initial large reduction in congestion 

duration was because of the completion 

of major road projects.

n Public relations. Education of drivers and 

stakeholders on managed motorway features 

is important for successful operations. Projects 

are driven by desired outcome; therefore, 

understanding the overall goal and clearly and 

successfully communicating the goal to the 

public are critical. Experiences in Europe have 

identified radio and Web-based approaches 

as the best methods to reach the public. In 

some cases, the driver culture of the area may 

influence how treatments are implemented 

and communicated to drivers.

Findings for Planning 

n Safety concerns. Politicians, citizens, designers, and implementers in England, Germany, 

and the Netherlands had concerns similar to 

those expressed in the United States about 

potential or perceived reductions or changes 

in safety because of the application of some 

management strategies. The Highways 

Agency in England developed a hazard index 

to systematically evaluate the potential driver 

safety risks and aid in its decision to implement strategies and design choices on 

managed motorways. The agency uses a 

risk-based approach for transitioning the 

shoulder from an emergency lane space to 

a travel lane. Its research has indicated that 

the risk of eliminating shoulders (at least 

for part-time use) is minimal. 

n Evaluation of feasibility. Before managed 

motorway treatments were implemented, 

extensive studies were conducted 

to determine a technique or strategy 

appropriate to the problem and the 

roadway geometry. 

n Stakeholders. It is important to bring all 

stakeholders (enforcement, trucking, traveling 

public, agency, and government leadership) in 

at the early stages of the planning and design 

process. Emergency management was a key 

stakeholder group to educate and strategize 

in several European countries. 

n Legislation and policy. In England, Germany, 

and the Netherlands, national or state policy 

was a driving factor in implementation of 

managed motorway concepts. In 2003 the 

German state of Hessen initiated “CongestionFree Hessen 2015,” which specifically identified 

future technologies, traffic management, and 

mobility services as tools to optimize traffic 

flow and increase safety. In England, longstanding public concern about the environmental cost of highway expansion drove the 

development of various reports and policy 

initiatives that emphasized sustainability in 

seeking solutions to roadway congestion.

Findings for Lessons Learned

n Corridors in progression. There is an evolutionary path in the appropriate design and 

operational strategies of individual freeway 

corridors. As traffic and congestion levels 

increase in the corridor, different approaches 

and management strategies should be 

considered to accommodate changing 

needs, risks, and appropriate tradeoffs.

n Effective use of space. Several European 

countries dynamically manage the freeway 

space available. For example, they may use 

the paved shoulder space for traffic movement 

during peak travel periods and as a typical 

shoulder during offpeak travel times. 

n Importance of collaborative design process. 

Actively and effectively managing roadways 

requires coordination across disciplines, and 

collaboration among planning, operations, and 

design is imperative. In England the Highways 

Agency uses the operational regimes to determine design criteria rather than adhere strictly 

to design standards. 

n Operating costs. Stable, consistent, and 

ongoing funding for operations and maintenance is a critical component of the managed 

motorways concept. 

n Capital costs. The M42 in England was 

designed conservatively on spacing of gantries, emergency refuge areas, and ancillary 

equipment. After monitoring operations and 

results, the English have made incremental 

changes based on data that demonstrate they 

can maintain or improve traffic flow and safety 
8 EXECUTIVE SUMMARY

while increasing the spacing between gantries 

and refuge areas and reducing lighting to 

lower costs. 

n Complementary treatments. Many applications are complementary. For example, line 

control (or variable speed limits) and shoulder 

running installations result in complementary 

and synergistic operations and benefits. 

n Benefits. The countries visited report that 

managed motorways result in improved 

safety, reliability, and air quality and can 

be provided at less cost than traditional 

capacity expansion. 

n Public perception. The countries recognize 

that the proposed operational scheme will 

be successful only if the public perceives it 

to be successful (despite what data may say).

n Procurement. Construction methods are 

evolving as a result of the high degree of 

technology required for managed motorway 

concepts. England has used innovative 

construction methods and offsite locations 

to assemble managed motorway gantries, 

signs, and ancillary equipment and realized 

efficiencies in buying equipment.

n Sign messages. England, Germany, and the 

Netherlands have found that it is important 

to test new sign messages with users before 

implementation.

Next Steps 

As evidenced in this report, the scan team believes 

that much can be gained in the United States by 

implementing several concepts and strategies 

observed during the scanning study. The next 

critical step is the implementation phase. Scan 

team members are communicating key findings, 

promoting implementation ideas, and advancing 

the adoption of key approaches and practices 

described in this report. The scan team is also 

seeking champions from transportation agencies 

and organizations to implement policies and 

practices using flexibility and innovation in 

designing freeways for improved safety 

and operational performance. 

REFERENCES

1. Hessisches Landesamt fur StraBen- und 

Verkehrswesen. “Temporary Use of Hard 

Shoulders” (2010). Staufreies Hessen 2015. 

Available at http://www.staufreieshessen2015.

de/irj/Staufrei_Internet?rid=HMWVL_15/

Staufrei_Internet/nav/09f/09f20b18-af71-

ff11-f3ef-ef91921321b2,f4c7b18a-f71f-f11f3efe-f91921321b2c,,,11111111-2222-3333-4444-

100000005003 percent26overview=true.

htm&uid=09f20b18-af71-ff11-f3efef91921321b2. Accessed June 15, 2010.

2. Hessian State Office for Road and Traffic

Affairs. “Congestion Free Hessen 2015: 

A Success Story” (2009). Available at http://

www.staufreieshessen2015.de/irj/servlet/prt/

portal/prtroot/slimp.CMReader/HMWVL_15/

Staufrei_Internet/med/9da/9da0999c-199c021f-3efe-f91921321b2c,22222222-2222-2222-

2222-222222222222. Accessed June 15, 2010.

3. Germany. “Duration of Congestions on 

Motorways in Hessen” pamphlet (undated). 

Project Management Congestion Free 

Hessen 2015.

OFFICE OF INTERNATI

FHWA/US DOT (H

1200 New Jersey Ave., SE

Washington, DC 20590

Tel: (202) 366-9636

Fax: (202) 366-9626

international@fhwa.dot.gov

www.international.fhwa.dot.gov

Publication No. FHWA-PL-11-003

HPIP/10-10(3.5)EW