Traffic and Highway Safety

Objections

We object to the Proposed Development on the grounds that the traffic modelling for the Green Lane / Central Road signalised junction is insufficient, selectively framed, and fails to meet the standards required for robust transport assessment. This junction is already a known bottleneck. Cutting corners on modelling and dismissing community concerns will only compound congestion, compromise safety and erode public trust. 

Inadequate Modelling of Green Lane / Central Road Junction and Dismissal of Community Concerns 

We object to the Proposed Development on the grounds that the traffic modelling presented for the Green Lane / Central Road signalised junction is insufficient, selectively framed, and fails to meet the standards required for robust transport assessment. Furthermore, the applicant’s dismissal of legitimate community concerns during the consultation process undermines public trust and transparency. 

The applicant has explicitly acknowledged that the Green Lane junction is “too complex for basic modelling.”  and proposed to provide technical details and to summarise the the minimal impact at Green Lane and requested for TFLs support on the approach.  This decision to avoid appropriate modeling appears to be based on cost and convenience, not technical suitability

See below from Comms between Iceni and TFL in FUL-Transport_Assessment_Part_2 (pg 10 and 11)

Unrealistic Car Ownership Assumptions

• Census data (Table 6.5) shows that 73% of households in the 3 boroughs (RBK, LBM and Sutton) own a car or van.

  • To calculate the total number of households with cars in Kingston, Merton and Sutton: 

108,955 + 44,736 + 13,352 = 167,043 households with cars

 • To calculate the ratio of cars to dwellings in local MSOAs:  167,043 (households with cars) / 229,700 (total households in local Boroughs) = 0.73

• Despite this, the applicant assumes that only residents with access to the 90 allocated parking spaces will own vehicles — This assumption is both unrealistic and biased. It results in a significant downward adjustment of car usage—from 43% (as per census data in Table 6.4) to just 8%—based solely on parking provision. This represents a mathematical manipulation rather than a reflection of actual potential travel behaviour.

• This is a mathematical manipulation, not a reflection of actual travel behaviour, especially in an area with poor public transport.

Delivery Traffic Underestimated

• The application estimates 202 delivery trips per weekday, evenly spread across 12 hours.

• This fails to account for peak-hour clustering, particularly in the morning and early afternoon (a weighted distribution should be applied for accuracy), which would increase congestion and safety risks.

Healthy_StreetTransport_Assessment_Part_1 - section 6.23

"In order to calculate the trip generation associated with servicing for the proposed development, accepted TfL guidance recommends a ratio of deliveries per dwelling across a typical day of 0.43. Motspur Park Gas Holder Site – Healthy Streets Transport Assessment Using this ratio – the development is anticipated to generate in the order of 252 associated trips with the dwellings. However, in reality this does not equate to one vehicle per trip, as a number of trips will be ‘linked trips’ which represent one vehicle visiting multiple homes within the development. As such, the 252 servicing trips are reduced by a factor of 20% to account for linked trips – which equates to a total of 202 trips across a typical weekday. Dividing this across a typical 12-hour day gives an hourly delivery rate of 17 deliveries per hour associated with the development. The 20% linked trip assumption was applied as part of a previously approved St Williams Homes London scheme, whereby TfL provided this assumption to agree servicing trip rates. "

The reduction of 20% is based on a precedent from a St William Homes scheme elsewhere in London, but the applicant fails to demonstrate that the same conditions apply to Motspur Park. Specifically:

• No evidence is provided that the size, layout, or delivery infrastructure of the St William scheme is comparable to this proposal

• Motspur Park’s poor PTAL rating (0–1) and suburban street network may limit the efficiency of multi-drop deliveries

• The development’s scale (586 dwellings) and constrained access points may actually increase the number of single-destination trips

Without site-specific justification, applying a blanket 20% reduction risks underestimating delivery traffic, especially during peak hours when congestion and safety risks are highest.

Flawed Baseline Survey

Healthy_StreetTransport_Assessment_Part_1 - section 6.29 

"To provide baseline data, Manual Classified Count (MCC) surveys were undertaken on Thursday 3rd July 2025. This was a normal school day for Green Lane Primary School."

This framing is misleading. While technically a school day, the survey was conducted during early July, when:

• Certain classes were already away, reducing pupil numbers and associated traffic

• Weather was dry and warm, increasing the likelihood that children walked or cycled rather than being driven

• The school was not operating at full capacity, meaning traffic volumes were atypically low

Conducting a traffic survey on a single summer day — under optimal conditions — does not constitute a robust baseline. A credible assessment should include multi-day surveys across different seasons, accounting for:

• Wet weather conditions

• Full school attendance

• Variability in traffic patterns due to term schedules and local events

Without this, the applicant’s conclusion that traffic impact is “minimal” is based on best-case conditions, not representative data.

We urge decision makers to;

• Reject the application and request an independent VISSIM-G model of the Green Lane / Central Road junction.

• Reject the Trip Generation Assessment as unreliable and misleading

• Require a robust, worst-case scenario analysis using representative data and accurate dwelling counts

• Model all critical junctions as per TfL’s guidance, including the A2043 / Green Lane intersection

• Consider cumulative impacts from nearby developments and realistic car ownership patterns