FORWARD PLANNING & PROJECTS TRANSPORT PLANNING

John Davies Development Control Team Town Hall Extension, 6^th Floor

Stephen Burke, Ext: 5896

12^th September 2002

Former BR Staff Association Club, College Lane , NW5

Demolition of vacant clubhouse and construction of 20 mews houses arranged in terraces of 2 and 3 storeys with lower ground levels and a block of 10 flats comprising studio, 2, 3 and 4 bedroom fiats. The provision of underground car parking with ramped access from the site entrance off Little Green Street

Reference: PEX0100663/R2

Key points:

1. Highgate Road is heavily trafficked. The most recent screen line count was taken in 2000, at a point just south of Little Green Street. This gave a 2-way 24 hr traffic flow in excess of 10,000 vehicles per day and 2-way hourly flows varying between 9.00 and 1,100 vehicles per hour.

2. The applicant has produced a report detailing the expected traffic generation for residential use and various uses under Use Class 02.

Transport observations

Introduction

The application is to redevelop a backland site to the east of Highgate Road for housing. The site was formerly used as a social club but has lain vacant for some time. The proposal would comprise 30 dwellings with 13 parking spaces,

Traffic generation

I have interrogated the TRAVL database for surveys of residential sites in London and the average trip rate was 2.0 two-way Journeys per dwelling per weekday. Some care is needed in applying these rates. Trip generation is largely determined by car ownership, which would be restricted in the proposed development. Obviously, the application of these rates to the whole site would produce an over estimate since many of the units would be car-free. We could just apply the rate to the units with parking. However, since residents would pay a premium for theses units, the level of car owner ship is likely to be high, i.e. approaching 100%. However, the average level of car ownership of sites in the London survey was only 58% so this would result in an underestimate. A correction could be made by factoring up the trip rate by the level of car ownership in the surveys. This would give a trip rate 3.5 two-way journeys per dwelling per weekday.

Taxi trips were recorded separately in the TRAVL surveys. The average London rate was 0.05 trips dwelling per weekday, although this would probably be higher with car-free housing, say 0.1 trips dwelling per weekday.

Deliveries were not included in the surveys.

The expected generation would be around 50 two-way journeys per weekday.

Access.

It is proposed to use Little Green Street as a vehicular access. Little Green Street is an adopted highway with a narrow footway on the northern side. The width of the footway varies between 0.8 and 1.3 m and the width of the carriageway varies between 3.0 and 3.6 m. The carriageway is less than the minimum width required for two vehicles to pass. Little Green Street is a pedestrian through route, which links both College Green and Ingestre Road with Highgate Road . A zebra crossing has recently been placed in Highgate Road , opposite Little Green Street, in response to pedestrian demand.

The narrow width of Little Green Street makes it unsuitable for the passage of moving traffic. The minimum width given in Design Bulletin 32 1992 paragraph 3.17 is the width necessary for two vehicles to pass on another, i.e. 4.1 m.

Design Bulletin 32 1992 provides scope for narrowing to as much as 3.0 m in special circumstances with certain provisos. The first being that the narrowing should be no more than 15 m in length and atso there should be suitable passing bays (DB32 Paragraph 3.20). Neither of these conditions would be met on the proposed scheme since the narrow carriageway would be approximately 65 m in length.

The problems associated with the long single carriageway are as follows.

• Vehicles will inevitably meet on the access road.

• Neither vehicle would have priority so it would be unclear which one should reverse.

• Both reversing manoeuvres would be unsafe. The vehicle intending to leave the site would have to reverse around a corner into a pedestrianised area. Alternatively, the vehicle intending to enter the site would have to reverse back over a pedestrian footway and into to Highgate Road . This would endanger both pedestrian and traffic in Highgate Road . Highgate Road was a heavy traffic flow throughout much of the day. The driver may have a considerable wait for a suitable gap to appear in the traffic flow.

Furthermore, it would be necessary to reverse onto a zebra crossing, presenting an additional hazard to pedestrians.

• Vehicles approaching the site from the southeast would have to wait in the middle of Highgate Road for an opportunity to turn right. Following the recent installation of a zebra crossing, the point where vehicles would wait is now an area that should be kept clear and has the appropriate zigzag demarcation. Waiting vehicles would obscure both driver and pedestrian and visibility, thus compromising safety for the users of Highgate Road .

• Drivers about to turn right into Little Green Street would need to concentrate on the oncoming traffic, awaiting a suitable gap before proceeding. If an exiting vehicle were to appear in Little Green Street at that point in time, as it conceivably could, the right turning driver would be faced with a difficult dilemma. Stopping immediately could place the right- turning car in the path of oncoming traffic while proceeding would place the car in direct conflict with the exiting vehicle, since there is no space on Little Green Street for either vehicle to wait.

• Even if a directional priority were to be applied to Little Green Street through a Traffic Management Order, it would only apply to the access road but not to vehicles approaching from Highgate Road or the private land within the site. In any case, such orders are normally only applied where there is a safe space for vehicles to wait.

The proposed development would result in the access road taking two-way traffic and as shown previously, the expected traffic flow would not be insignificant. The safety hazards detailed above mean that the access is clearly unsuitable for the proposed use. I would therefore recommend a refusal on the grounds that the site does not have a safe access.

Refuse collection

The drawings show a "turning circle" at the northwest end of the site. The area is lot adequate to allow a refuse vehicle to carry out a three-point turn. Without a turning facility, refuse vehicles would have to reverse considerably longer the K3m distance recommended by DB32 Paragraph 3.55. To overcome this problem, there would need to be a suitable turning head, preferably on adopted highway. This would involve the creation of a new section of highway through an agreement under Section 38 of the Highways Act linked to a S106 agreement. The developer would need to dedicate the land and fund the highway works. Highway Engineering would need to be consulted.

The maximum carry distance between a bin storage area and a refuse vehicle i s governed by UDP Standard DS9, is 25m. The bin area shown at the Southwest corner of the site greatly exceeds this distance.

Access for fire appliances

London Fire & Emergency Planning Authority (LFEPA) Fire Safety Guidance Note 29 recommends that turning facilities required on a cul-de-sac exceeding 20m. Accordingly, the turning facility referred to previously in the section on Refuse collection should allow a fire tender to execute a three-point turn.

There are different standards governing the access width required for fire tenders. BS 5588-1:1990 recommends a minimum carriageway width 3.66 m, or 2.75 m if it is clear of parked cars. LFEPA recommend a minimum carriageway width 3.7 m. London Fire Brigade should be consulted since the access does not satisfy the most stringent of these requirements.

The maximum fire hose distance between the tender and the front door of any dwelling, recommended by both BS 5588 and LFEPA is 45m. This clearly cannot be achieved with the proposed layout.

Assessment and Comparison of Traffic Generation Potential

The above document, dated January 2002, has been submitted by Buchanan Consulting Engineers. The document compares the traffic generation of residential development with potential uses within Use Class D2.1 would comment as follows.

• The current traffic generation of the site is zero and has been for some time. No information is provided for when the site was last in use. Therefore a valid comparison has not been made between the existing and proposed scenarios.

Within the report, an attempt has been made to predict the potential traffic generation for a fitness centre and a community centre by extrapolating values from a national database (TRICS). None of the sites in the database are in London ; they are located in areas that are more car dependant. Similar sites in London would probably have a lower generation rate.

The sites in the database were presumably a) built in areas where there was a verified demand and b) were successful. There is no evidence to suggest that similar activities in the application backland site would be as successful in generating patronage. The questionable suitability of the site together with the use of out of London data suggests that the generation rates have been over estimated.

Any attempt to resurrect the site for D2 use would probably be subject to

planning approval and the safety of the access would need to be assessed as part of the approval process. This could lead to a refusal.

• No data is given on the level of car ownership for the residential sites in the (TRIGS) survey but as with the TRAVL database, it was probably considerably less than 100%. The generation data has been applied only to the component of the development with parking, where car ownership is likely to be 100% but using data from housing with a lower car ownership. The result is that the residential traffic generation has probably been underestimated.

• The survey takes no account of deliveries or taxis and these would also add to the total traffic generation.

I understand the applicant would be likely to appeal any refusal. We should then set down certain requirement in case a future appeal is allowed.

• There needs to be an adequate turning facility for refuse collection vehicles and fire appliances.

• The site needs to be subject to a car-free / car-capping agreement.

• Refuse should be stored within carry distance of collection vehicles.

• The required distances between fire appliances and dwellings should not be exceeded.

• The applicant should prepare a Transport Impact Statement to include a Safety Audit of the access, as required by UDP Policy TR19. The safety auditor could then be liable in the event of a claim being made against the Planning Authority, following an accident attributable to the layout of the access.