Are road closures in Cambridge causing more congestion?

What are modal filters and low traffic neighbourhoods (LTNs)?

Over the past few years, Cambridgeshire County Council and the Greater Cambridge Partnership (GCP) have introduced modal filters – features such as planters, bollards or concrete blocks – in many streets across Cambridge to create low traffic neighbourhoods (LTNs). The filters prevent through-traffic by certain types of motor vehicle, immediately making the road much safer for walking and cycling.

The filters in Cambridge on Bateman Street, Carlyle Road, Luard Road, Nightingale Avenue and Storey’s Way started out as experimental measures to provide safe space for walking and cycling during the pandemic, but have since become permanent. Modal filters are not a new feature of our streets, though. The one on Leys Road/Highworth Avenue, for example, has been in place for more than 50 years. You can learn more about long-standing modal filters in Cambridge here.

What impact do low traffic neighbourhoods (LTNs) have on motor traffic?

It is clear that restricting through traffic on local streets using modal filters reduces traffic inside low traffic neighbourhoods (LTNs) by a large amount.

One frequent criticism of LTNs is that they simply push car use to the periphery, to busier main roads. While the periphery of some LTNs may see short term increases in traffic (either on specific streets, or on average), this tends to dissipate over time, so restricting traffic on local streets does not increase congestion in the wider area in the medium and long term. As well as boosting the numbers cycling inside their boundaries, there is also evidence that LTNs increase the number of people cycling in the area surrounding them as well. Some studies have also suggested that people living inside LTNs are less likely to own a car. You can read more about the impacts of LTNs on traffic in this study of schemes in London.

LTNs also do not increase emergency response time or increase street crime.

Stopping rat running on residential streets is a long-running objective of the people who live there as well as of the councils. Across the country, communities rightly want their local streets to be safe and calm spaces that are not subject to speeding vehicles or high volumes of cars using streets that were never intended for this.

Analysis shows that 70% of all streets by length in Cambridge are Low Traffic Neighbourhoods that do not allow through traffic. Only 12% still have rat running. The other 18% are the main roads. It is therefore already the norm that local streets are not through-streets. 

Council policies over decades have been to treat local streets as access streets, and main roads as through-roads. Sustainable transport organisations agree this is a sensible objective.