Considering Air Quality and Inclusive Design with Traffic Management Methodology

Climate change, air quality, safety and a healthy economy are at the top of the Mayor of London’s agenda and keeping London moving sustainably is the aim. Transport policies have a focus on modal shift which includes; electric fleet growth, increased use of public transport and encouraging more and safer walking and cycling will help us achieve the targets that have been set. Therefore, any interventions which impact such policies require careful assessment.

Cycleway 3 (CW3) is one of London’s busiest cycle routes with 1000’s of people benefitting from the segregated facilities every day. Temporarily closing such routes can have detrimental impacts especially with promoting sustainable transport.

This subcontractor working on behalf of the main contractor were tasked with scaffolding the eastern fascia of the Upper Thames Street tunnels as part of the Millennium Bridge House development. There are three tunnels in total to accommodate east and westbound traffic and one of the tunnels dedicated for CW3. Due to width constraints and safe working concerns the cycle tunnel needed closing therefore a need to divert cyclists. Alternative cycle routes ideally supply a similar utility as the existing route e.g. segregated from traffic to reduce conflict. However, the proposed diversion route had limited cycle facilities and placed cyclists on busy roads which included HGVs, buses, coach parking and numerous junctions to contend with.

The dilemma – Transport for London preferred night-time working for the diversion as there would be reduced cycling and subsequently less disruption on CW3. City of London Environmental Team preferred daytime working to reduce night-time impacts on residents from noisy working. Additional issues with night-time working is the available hours to complete works and additional costs for unsociable hours.

The collaboration – TfL’s Strategic Operations team met with City of London, the contractor and subcontractor on numerous occasions to look at the challenges and if there were opportunities to mitigate the issues. This involved site meetings which included walking and cycling the route, on-line discussions and an agreed open and flexible approach to working that considered all stakeholders.

The proposal – To utilise the adjacent eastbound traffic tunnel which has one running lane and a hatched area along the full length of the tunnel to use as a replacement cycle route thus enabling daytime working.

The concern – Directing cyclists through a tunnel with high vehicle flows raised concerns of the levels of pollution they would be exposed to.

Air Quality – Firstly they required approval to use the tunnel before any investigation took place. This included requesting information on the existing venting system and how reliable it was. They received approval and were informed that the vents are in good working order. They then wanted to check if pollution levels breached the standards during peak times and to assess this they undertook a NOx level survey which supplied zero breaches. To support the proposal they looked at the results from the introduction of the Ultra-Low Emissions Zone (ULEZ). Reports show significant drop in air pollution plus 13,500 fewer polluting cars being driven into the zone daily and 77 per cent of vehicles in the zone now meet the clean emissions standards. A test of the route was undertaken to time how long a cyclist is likely to be within the tunnel and exposed to NOx. Based on a comfortable rate of pedalling this took 40 seconds. To accommodate the concerns cyclists may additionally raise they agreed on installing mask stations at each end.

Safety and access – The tunnel has a speed limit of 30mph and there are existing cylinders within the tunnel which maintain segregation between the running lane and hatched area. The tunnel has good lighting and continuity for increased comfort. They then looked at how to supply access to the tunnel from each end as there were kerbs and islands to negotiate. To manage this they decided on installing asphalt ramps with generous gradients to accommodate the larger cycles that used the route e.g. cargo bikes. Barriers with appropriate signage and white tape would help to direct both directions of cyclist and marshals on hand at each end to supply assistance.

Results – A traffic management layout that accommodated accessible and safer cycling was agreed and approved by TfL. The works took one week to complete compared to the three weeks forecasted for night-time working therefore saving two weeks of disruption. Working during the day helped the contractor install the works smoothly, on time and at a reduced cost. The method met the needs of both highway authorities. There was no need to divert cyclists on a route that could supply conflict concerns. No motor traffic was impacted. The method can be re-used for future tunnel works.