We measured Prague’s bike boxes: one third of them do not meet the standard

In response to fatal accidents involving cyclists at intersections in Prague, a team from our Laboratory of Sustainable Urbanism examined the real conditions of so-called advanced stop lines (bike boxes). They focused on the wider city center. What conditions are set by standards and regulations, and to what extent are they followed in Prague’s streets? Where is it necessary to push for changes in order to prevent accidents as much as possible?

What is an advanced stop line?

It is a type of horizontal road marking, code V 19 – a designated space for cyclists. In the cycling community, it is also known as a bike box or informally as a “pen.” According to Czech technical standard TP 81 (2018 amendment), it should be placed at signalized intersections wherever cycling traffic is not prohibited.

This space allows a cyclist to pass through the intersection first, be clearly visible to all road users, and breathe minimal exhaust fumes while waiting in a traffic queue. By law, cyclists are expected to use this space (unless doing so would endanger safety or traffic flow).

More information: https://ebook.nakolejensprilbou.cz/prostor-pro-cyklisty

A similar function is served by an advanced stop line in dedicated cycling lanes. However, the regulations for its parameters are slightly different and in some cases insufficient.

What should the cycling space look like?

The risk associated with using bike boxes does not lie only in correctly judging the situation and timing overtaking in queues, but also in their dimensions. In what size of bike boxes are cyclists actually visible from the seats of oversized SUVs and trucks?

Technical standard TP 81 recommends a length of 3 meters, with a minimum of 2 meters. In the case of an advanced stop line in a dedicated cycling lane, the minimum is only 1 meter, which we consider clearly insufficient—especially in situations where turning vehicles cross a parallel bike lane.

Požadavky TP 81 na prostor pro cyklisty 

Requirements of TP 81 for the advanced stop line in a dedicated bike lane

Prague Standards require more

In the Prague context, the standards for bike boxes have been revised in a draft version of the Model Solutions for Active Mobility Standards. These standards consider a typical bike box length of 3.25–3.5 meters, while also allowing for extension in cases where higher cycling volumes or the presence of heavy freight vehicles and buses is expected.

The minimum size in exceptional cases (“exceptional emergency substandard solution”) essentially mirrors the national technical requirements (see image below).

The advanced stop line in an extension of a dedicated bike lane is not further specified in the model design guidelines, which we consider unfortunate, and we pointed out this shortcoming during the consultation process. TP 81 sets only a minimum offset for the stop line, regardless of the specific situation. When motor vehicles turn across a dedicated cycle lane, a 2-metre length is clearly insufficient.

In 2024, a fatal accident occurred in Prague on Ústecká Street precisely at this type of advanced stop line, where a truck driver failed to notice a cyclist.

Analysis of advanced stop lines in the wider city centre

Based on the conditions above and taking into account newly proposed model solutions, we evaluated in Prague’s wider city centre especially the length of cyclist waiting spaces and the distance of stop lines without bike boxes from pedestrian crossings. The evaluation categories were divided into standard, substandard, and inadequate. The results are shown in the maps below, allowing you to easily check the locations you or your friends move through.

As stated in the model solutions, the required length of bike boxes may depend on whether large vehicles—where peripheral visibility issues may occur—are frequently present. Roads of class I are therefore highlighted in red on the map, as a higher occurrence of such vehicles is expected there.

Advanced stop lines in dedicated cycle lanes are assessed separately, taking into account the risk of conflict with turning vehicles. The evaluation methodology is shown in the table below.

Table of problem assessment (corresponds to the map display)

Evaluation symbology shown on an orthophoto example and complete legend

Maps to download 

Evaluation

Conditions in Prague’s wider city centre are, according to TP 81, generally in order with a few exceptions. However, they only meet the new Prague standards defined in the Model Solutions to about half to two-thirds, depending on the specific type of measure.

The model solutions primarily apply to newly constructed intersections, but any substandard location in areas with higher traffic intensity may ultimately contribute to an accident similar to the one that occurred in autumn 2024 near Eden in Prague, in which a young female cyclist was killed.

The critical bike box at that location is 20 cm below even the Prague standard. Given the traffic intensity there, it would clearly require an above-standard extension.

Table of case frequency in Prague’s wider city centre

We identified a high proportion of cases where advanced stop lines are completely missing. For readers, we also assessed their actual necessity. For example, bike boxes are not needed in left-side parallel traffic lanes. However, in more than half of these cases, bike boxes would in fact need to be added.

Check the safety of places you know on the map

Our outputs can serve as a basis for discussions with municipal districts or the City of Prague itself, or for local governments to comprehensively assess the level of risk in current designs using available data. We will therefore send the analysis to the relevant authorities and call on them to address especially missing or non-compliant bike box installations. You can also support improvements by submitting your own requests to local authorities.

Improving safety at intersections

Intersections are long-term hotspots for traffic accidents, yet current legislation does not sufficiently address the safety of cyclists, who are less visible in traffic. Bike boxes are one of the few measures currently available to minimise risk, and it is positive that Prague’s design standards are at least formally stricter than national technical regulations.

However, cyclists do not move only within Prague, so it will also be necessary to revise conditions in national (binding) standards based on practical experience.

Advanced stop lines in dedicated bike lanes appear only rarely in Prague, which—given their insufficient regulatory parameters—is actually beneficial. If they are to function effectively, especially at conflict-prone locations on higher-class roads, their length should at minimum match bike box standards.

A significant improvement to intersection safety would be the long-awaited introduction of clear rules for so-called indirect left turns, which allow cyclists to cross intersections in this direction in a nearly conflict-free manner. The proposed model solutions also address this topic, including necessary legislative changes.

Through the initiative Výzva Nula, which aims to reduce traffic fatalities to zero, you can also support safer conditions for the most vulnerable road users.

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