Traffic safety on one-way streets with contraflow bicycle traffic

1. Existing conditions

Urban one-way streets serve primarily to channel and regularize motor traffic. For bicycle traffic, on the other hand, they interrupt many direct connections and make the use of low-traffic local streets more difficult, leading bicyclists to travel illegally on one-way streets in the wrong direction, or to move over to parallel arterial streets.

The topic of opening one-way streets to contraflow bicycle traffic was controversial for years in Germany (see. DRAEGER 1997). Questions about the effect on traffic safety and of the proper approach under the traffic laws led local governments to various solutions, or generally to avoid contraflow installations.

Contraflow sidepaths and, less often, bike lanes, have, however, been installed in some places for decades. In many places, the "false one-way street" solution has been most widely used, mainly to avoid problems of conformity with the traffic law. Before 1997, some cities nonetheless opened true one-way streets to contraflow bicycle traffic, at least in some selected districts, by way of exceptional applications of the traffic law. Figure 1 illustrates these.

These developments, and the mostly positive experience to date, led to a provision in an amendment to the traffic law (StVO) that went into effect on September 1, 1997, allowing contraflow bicycle travel on one-way streets under certain conditions.

The provisions in the StVO and in rules for application of the StVO (VwV-StVO) for opening of one-way streets were, however, not put into effect until December 31, 2000, due to lack of sufficient research support. Experimental evidence was to be collected to determine whether, all in all, and particularly as they affect traffic safety, such measures are justifiable.

The goal of the research plan of the Federal Road Research Institute (Bundesanstalt f�r Stra�enwesen), completed in 2000 (PGV/BIS 2001) was to look more deeply into the issue of traffic safety on one-way streets where contraflow bicycle traffic was permitted according to the new StVO provision, and to evaluate these streets in comparison with other one-way streets where contraflow bicycle traffic was prohibited. In this way, a well-founded decision could be reached as to whether the experimental provisions could stand after the year 2000, and whether modifications to them should be recommended.

In what follows here, the most important results and conclusions from the research are reported. These have already led to a permanent status for the StVO provision.

2. Research phases

• An initial inquiry among cities with more than 20,000 inhabitants provides the first overview of the application of the amendment to the law and how it is received by the municipalities.
• All crashes involving a bicyclist on a one-way street in 1999 in several provinces and additional selected regions are examined. A special collection of crash data and additional information about how crashes occurred is sent directly by local police departments.

  611 crashes on one-way streets were recorded, of which 436 were on local streets, which are of the greatest interest in this inquiry. The crashes were categorized according to the direction of travel of the bicyclist and the traffic laws that apply on the one-way street, and were evaluated in terms of the most important characteristics (e.g., outcome, other party involved, location, type of crash, age of the bicyclist etc.).

• 15 cities were then chosen based on the results of the inquiry. One-way streets were identified and categorized according to their cross-section, parking arrangements etc. The crash records for a total of 669 streets were collected and correlated with the characteristics of the streets. In this way, the distribution of crashes, as well as other information, was made available, and one-way streets with crashes could be compared with others that were crash-free in the same city (and where the same legal provisions had been applied). A before-and-after comparison of crash incidence in 1997-1999 also was carried out on the selected one-way street segments in the cities which were opened as in accordance with the StVO provision. Bicycle counts according to direction of travel and the bicyclist's position in the corridor were used to extend the analysis.
• Using traffic analysis methods, the traffic and interaction sequences were determined, and it was established which constellations of problems and safety risks occur with different configurations for contraflow bicycle traffic on one-way streets. Twelve situations were chosen in which bicycle and motor traffic were heavier and an increased likelihood of problems could be anticipated.
• The results of all of these steps were compiled, and conclusions were drawn regarding traffic safety in relation to the legal, traffic and geometric conditions on the one-way streets.

Recommendations for amendments to the law and for measures that might be taken in order to make contraflow travel on one-way streets safe, were discussed with experts, i.e., in the context of work of committees of the Road and Traffic Research Society (Forschungsgesellschaft f�r Stra�en und Verkehrswesen).

3. Conclusions of research

Amendment to the law and its reception by the municipalities

During the research phase, many cities and towns were wary of opening one-way streets. In part, they feared having to undo measures that had already been put into place, in case the new provision was not made permanent. But there were other reasons as well:

• The burden of proof required by the rules for application of the traffic law, and in some cases the costs and staffing associated with them, were regarded as too troublesome.
• Cities which had already installed false one-way streets before the 1997 amendment to the law mostly kept them as they were, to avoid the cost of new signage.

Many municipalities began to open one-way streets in the network of local streets immediately after the amendment. An area-wide opening, however, was only carried out in one case.

The documentation and evaluation of traffic and crash situations required in the rules for application of the traffic law are only rarely fully carried out by the authorities responsible for the streets. Only one example of withdrawal of an opening of a one-way street because of crashes involving contraflow bicycle traffic is known.

Results of the counts and behavioral observations

Depending on their location in the street network, one-way streets in 30 km/hour zones carry as many as 220 motor vehicles and 140 bicyclists per hour. As a rule, however, the traffic volumes are significantly lower.

In the one-way streets which have been opened, 40 – 45% of the bicyclists, on average, travel in the contraflow direction. This quantity is not significantly lower in the one-way streets which have not been opened; however, many more bicyclists traveling in the contraflow direction use the sidewalks (60% as opposed to approximately 20% in opened one-way streets, see figure 2). For pedestrians, then, there were markedly fewer restrictions and hazards on the sidewalk. Opening a one-way street also can shift bicycle traffic from main streets to local streets.

• Rules for application of the traffic law [Verwaltungsvorschrift zur Stra�enverkehrs-Ordnung (VwV-StVO)]

  A considerable simplification is intended in the rules for sign 220 in the rules for application of the traffic law for contraflow bicycle traffic. The following requirements for opening one-way streets will be imposed:

  - The speed limit will still be 30 km/h or less.

  - There must be sufficient width for passing, except for short narrow segments. There will be no specified narrowest dimension, other than 3.50 m for streets with significant truck or bus traffic.

  - The traffic pattern should be clearly laid out. If it can not be, a partial separation might be considered.

  - Where the location and traffic require, a safety space should be created for bicycle traffic.

  - Sign 220 with the supplementary sign should be placed at the beginning of the one-way street and at all streets and entrances, so that it is visible from all vehicles entering the one-way street.

In the future, some current requirements in the rules for application of the StVO will be discarded, for example that for area-wide bicycle traffic planning, testing of other options such as false one-way streets, short stretches for head-on encounters, and pre-evaluation of stopped vehicles. The requirement for evaluation of traffic and crashes that existed in the test phase has already been eliminated. These steps result in increased flexibility for jurisdictions to open one-way streets. The opportunities to open them are broadened, and the process is to do it is simplified. .

6. Summary

As the appeal of bicycling can be increased by opening one-way streets without negative effects on traffic safety or on other travelers, there need be no concern about wider application of the rule in the municipalities. The solution is generally advantageous for the users and the municipalities:

- Bicyclists can access residential areas area-wide and without the need for detours.

- Bicyclists have an increased ability to avoid arterial streets. That is safer, and generally more pleasant as well because of the reduced impediments from motor traffic.

- Through connections in the bicycle travel network are easier to achieve. However, attention must, as a rule, be paid to safety of crossings of arterial streets.

- The solution can be implemented quickly and relatively cost-effectively.

The proposed changes in the rules for application of the traffic law make it easier for municipalities to open one-way streets. With continuing positive experience in practice, a future reduction in the need for signage, and a general opening of one-way streets in connection with the 30 km/h speed limit rule (Z 274.1 StVO) may be considered, excluding only specific problem streets.

References

PGV/BIS (Planungsgemeinschaft Verkehr [Traffic planning collaborative], Hannover/ Büro für integrierte Stadt und Verkehrsplanung [Office for Integrated urban and traffic planning], Bonn): Verkehrssicherheit in Einbahnstraßen mit gegengerichtetem Radverkehr [Traffic safety on one-way streets with contraflow bicycle traffic], Berichte der Bundesanstalt für Straßenwesen [Reports of the Federal Road Traffic Institute] vol. V, 83; Bergisch Gladbach 2001

Alrutz, D./ Stellmacher-Hein, J.: Sicherheit des Radverkehrs auf Erschließungsstraßen [Safety of bicycle traffic on local streets], Berichte der Bundesanstalt für Straßenwesen, Heft V 37; Bergisch Gladbach 1997

Alrutz, D./ Tebbe, H./ Willhaus, E.: Führung des Radverkehrs in Einbahnstraßen [Accommodation of bicycle traffic on on one-way streets], in: Handbuch der kommunalen Verkehrsplanung [Handbook of Municipal Traffic Planning]; Bonn 1999

Draeger, W.: Die StVO-Novelle - Konsequenzen für die planerische Praxis [Consequences for Planning Practice], in: "Straüenverkehrstechnik" [Traffic Engineering]; vol. 12/1997

Stadt Frankfurt am Main: Modellversuch „Radfahren gegen Einbahnstraßen" [Prototype test of contraflow bicycling on one-way streets]; Frankfurt/Main 1998

Addresses of the authors of the present document:

Dipl.-Ing. Dankmar Alrutz, Dipl.-Ing. Detlev Gündel,
Planungsgemeinschaft Verkehr,
Große Barlinge 72 a,
30171 Hannover;

Dipl.-Ing. Wilhelm Angenendt, Dr. Werner Draeger,
Büro für integrierte Stadt- und Verkehrsplanung,
Meckenheimer Allee 67-69,
53115 Bonn