When the City of London developed a detour around construction at the Thames Valley Parkway (TVP) unknown planners failed to understand how cyclists behave in their normal progression through their urban environment. The result is that several dangers were created along the route. This article will discuss the first of three locations where those dangers exist: A left turn from Ann Street onto Talbot Street.

A Map of the Detour

Below is a map showing the area of the Thames Valley Parkway construction and the original detour route around it. There are three areas of concern along the route: 1. A required left turn onto Talbot, 2. A passage through the narrow Canadian National Railway (CNR) underpass, and 3. A steep downslope on Grosvenor St into a busy parking lot at Gibbons Park.

This present article will focus on the first of the three dangers: The left turn from westbound Ann Street onto northbound Talbot.

The Left-Turn Problem

The figure below shows an overall view of the area of the original detour where cyclists are asked to turn from the TVP onto Ann Street and progress eastward to the intersection with Talbot Street. They are then asked to make a left turn onto Talbot to take them toward the narrow underpass of the CNR underpass.

This Google Maps view shows the area where a left turn is required onto Talbot Street to take cyclists northward toward the narrow CNR underpass just south of Oxford Street.

The next figure below shows a closer, overhead, view of the intersection of Ann and Talbot. The red lines indicate the required motion that cyclists need to take to continue along the detour route. But the figure also shows the presence of a pedestrian crosswalk.

The figure below shows another view of the intersection looking north along Talbot Street. The red lines indicate the left turn required of cyclists to continue northward toward the CNR underpass. Again it can be noted that there is a pedestrian crossing at the intersection.

And again, the figure below shows a view looking eastward along Ann Street toward Talbot. This view also shows that there is a pedestrian crossing installed at the intersection. Those travelling eastbound on Ann and wanting to cross Talbot simply needed to press a button mounted on the pole and flashing pedestrian-crossing lights would be activated requiring all traffic on Talbot to come to a stop. So there should be no problem for cyclists who need to make the left turn: All they need to do is press the button on the pole. It appears that this may have been the logic of the unknown planners who developed the detour route.

How do I get across this busy road?

But what happens in practice? Never mind the theory, what did the planners know about what would happen in practice? Before answering that question we need to review some observations of cyclists in the area.

Video Observations of Cyclists

Throughout the summer of 2022 Gorski Consulting was involved in a traffic study at Blackfriars Bridge where it connected with the TVP. This location is just south of the area of construction at TVP. Five, 2-hour, videotaping sessions were conducted between May 29th and August 9, 2022. The actions of cyclists were monitored to determine the direction from which they entered the study area and the direction they took when exiting the study area. The table below shows the results of these observations.

The above table shows that 390 cyclists were observed to travel northbound toward the area of construction in the 10 hours of video observations, or 39 cyclists per hour. Also 68 cyclists were observed to travel westbound across Blackfriars Bridge, or about 6.8 cyclists per hour.

We wanted to explore how the detours affected the motions of cyclists so we conducted another 1-hour of video observations on August 23, 2022, or one day after the detour became active. This session revealed that only 24 cyclists travelled northbound on the TVP toward the area of construction, but 16 cyclists travelled westbound across Blackfriars Bridge. In other words a reduced number of cyclists used the original detour and this is noted in the drop in observations from 39 per hour to 24 per hour. And the observations seemed to support that some cyclists used the alternate detour route of crossing Blackfriars Bridge and travelling onto Gunn Street – and this is supported by the increase in observations from 6.8 per hour to 16.0 per hour. So these data provide some context to what is happening along the original detour route.

Next we conducted video observations at the intersection of Talbot and Ann Streets on August 24, 2022, over a period of 2 hours. At 15-minute intervals we noted the actions of cyclists passing through the intersection. The results from that study are shown in the table below.

As can be seen in the table, a total of 55 cyclists were observed in the 2-hours of observation. Those cyclists who were following the detour route toward the CNR underpass are located in the column “EB Ann Turn NB on Talbot” and there were 21 such observations, or 10.5 per hour.

So we can summarize by saying that during the summer of 2022, about 39 cyclists were travelling northbound on the TVP per hour before the construction began on the TVP. Just after the TVP was closed the number of northbound cyclists was reduced to 24 cyclists per hour. And then we see a further reduction in cyclists at the intersection of Talbot and Ann Streets to just 10.5 per hour. So the number of northbound cyclists using the original detour route dropped dramatically compared to the number of northbound cyclists before the construction began. In a way this reduction is helpful from a safety viewpoint because fewer cyclists became exposed to the unsafe conditions of the original detour.

We can now return to the issue of the the left-turning cyclists as they travelled eastbound on Ann Street and approached the left turn onto northbound Talbot. Recall, all they had to do to cross Talbot was to press the button located on the pole on the south-west corner of the intersection. Our testing confirmed that, as soon as that button was pressed the flashing lights became illuminated immediately and there would have been very little delay for cyclists. So what actually happened when these 21 cyclists were observed on video?

Of the 21 cyclists not a single one actually pressed the pedestrian-crossing button to cross Talbot Street. Eleven of the 21 cyclists waited patiently at the west edge of Talbot Street, some for a considerable time, before a gap was made available in traffic and they completed their left turn.

The remaining 10 cyclists never attempted the crossing. Instead they turned left onto the west sidewalk of Talbot Street and began riding northbound toward the CNR underpass. But the sidewalk on the west side of Talbot came to an end at the underpass. And this caused a dilemma. Since Talbot Street was filled with heavy traffic how were these cyclists going to get through the CNR underpass? In the next article we will present several examples of what took place.


What were planners at the City of London thinking when they created the original detour? Did they believe that cyclists approaching eastbound on Ann Street, and wanting to make the left turn to northbound Talbot, would deviate from their position on the road and come onto the south sidewalk to press the pedestrian crossing button? No one can read their minds.

However, if cyclists were expected to cross Talbot Street using the pedestrian crossing then that presented another problem. Cyclists are prohibited from riding within pedestrian crossings. So what next? After moving onto the south sidewalk and pressing the pedestrian crossing button was a cyclist expected to shimmy their bike over away from the pedestrian crossing and then cross from the eastbound lane of Ann Street? Clearly that would be impossible to believe because, from a practical sense, it just would not happen. That is not the way cyclists behave in the real world.

It was fortunate on the afternoon of the videotaping that traffic on Talbot Street was extremely dense such that on many occasions northbound vehicles were crawling forward at very slow speed. This improved the cyclists’ chances to enter the stream of traffic. But that favourable outcome would not always be there. It is likely that there would be occasions where traffic was less-dense and northbound vehicles could be travelling at the posted speed or higher. Then the ability of left-turning cyclists to enter the northbound stream could be worsened.

This is a view looking southward along Talbot Street showing the density of northbound traffic passing through the intersection at Ann Street on the afternoon of the video observations.

In such chaotic situations both drivers and cyclists learn to adapt and accommodate. Many drivers are alert enough that they detect the presence of a cyclist whose intention is to enter the lane in front of them. And cyclists are particularly careful not to enter traffic until they are sure they can do so in safety, or it could mean their life. So these accommodations help to mask the dangerous conditions that exist. However, over the long run, there is a higher probability that less-attentive drivers and cyclists will meet and the result becomes tragic.

This is why video observations such as those presented in this article are important. Even before a tragedy occurs we can make observations of the detour and draw conclusions about what might happen. And we can use this analysis to consider how we might improve the safety of cyclists in any further planning of detours.

There are two more articles forthcoming that will focus on the remaining two dangers along the original detour: 1. The narrow CNR underpass, and 2. The steep downslope of Grosvenor Street into Gibbons Park.