Saturday, 22 May 2010

Workshop background information

Important background information for this Wednesday's workshop is included below. This is the same as was included in your CCC Workshop packs, and has been reproduced here to encourage debate. Please bear in mind that the actual options themselves are yet to be presented and debated at the workshop. The CCC emphasises that this project is in its early stages and they are keen to get our input on the key issues in order to help develop a range of options.

Attachment 2: Background Information
St James Avenue Street Renewal Project (Harewood Road to Dalriada Street)
There are several factors that need to be taken into account when considering any proposed road designs and design options. Due to the amount of physical road space in a street, several of these factors conflict with each other. This document presents these factors so residents can understand the types of considerations and the impact that different road designs can have. By considering all these factors with an open mind and by getting the local residents views on what is important in this street, the project design staff will work to achieve the appropriate balance between these competing demands.

This project covers the 480m section of St James Avenue between Harewood Road and Dalriada Street. This section of St James Avenue is made up of a straight section that is approximately 330m long at the Harewood Road end, then there is an approximate 120 degree bend and another straight section that is approximately 150m long between the bend and Dalriada Street. 

Factors to Consider
St James Avenue is a local road. The primary purpose of local roads is to provide access to properties and local streets.

Traffic volume and speed surveys were undertaken in July 2008. Data was gathered outside number 14 and number 121 St James Avenue. The 7 day average results from outside number 121 showed that there was an average volume of 1,462 vehicles per day. The 85th% speed was 55.4km/hr, the 95th% speed was 60.5km/hr and the mean speed was 48.3km/hr.

There is a high parking demand at the Harewood Road of the street end as workers from nearby areas park in this street. At times there is high parking demand at the entrances to the park and there is low to moderate parking demand along the rest of the street from the residential properties.

St James Avenue is in the Shirley-Papanui community board area. The project area is residential but does include two entrances to St James Park.

It is one of the memorial streets in the area. The section between the bend and Harewood Road contains 42 mature oaks. The section between the bend and Dalriada Street contains 17 trees made up of a mixture of prunus and oaks.

Design life - the design life of the Street Renewal project is for 80-100 years. The decisions made now around roadway widths, the location of kerb and channel, drainage layout etc... will be in place for the next 80 plus years. Given the length of the design life, this reinforces the need for a well considered design to be adopted now that all parties will be happy with for the next 80 plus years.

Engineering design standards - there are several engineering design standards that need to be considered. Some of the significant standards that impact the development of designs for St James Ave include:
•    Traffic lanes must be at least 2.5m wide
•    Parking lanes must be at least 2.0m wide, and in certain cases they should be 2.5m wide.
•    Footpaths should be at least 1.5m wide
•    Excavation depths and widths are required to certain standards beneath the kerbs, driveways, footpaths and grass berm areas. To provide some context for this, typical excavation depths for carriageways in this area are approximately 40Omm deep and these extend at least 30Omm past the outside edge of the new kerb; new driveways are typically 4.1m wide and excavated to approximately 150mm deep; footpaths are excavated to approximately 10Omm deep; landscaping beds are excavated to approximately 350mm deep; new grass berm areas are excavated to approximately 75mm deep and the depth of under channel drainage pipes varies depending on the slope of the street.
•    The road width for a local road in the City Plan with traffic greater than 250vpd should be between 9.0 and 14.0m wide - any variations to these widths may require a resource consent.
•    Overhead and underground service conflicts. Careful planning is required to ensure that new kerb lines or trees are not overtop of underneath existing services in the street e.g. water pipes, sewer pipes, power, phone wires etc.... There are minimum offsets for different services that have to be achieved.

Traffic calming measures can be included to lower the speed environment of the street. These measures can include narrowing the street, creating localised narrowings, adding speed humps or raised platforms, utilising existing curves and/or intersections to encourage reduced speed and using street trees and/or landscaping to emphasise narrowings. The types of traffic calming measures that are recommended depend on the existing speed environment, the type of road, the traffic volume using the road and the desired speed environment for the street.

Road related stormwater runoff and drainage. Stormwater initially flows over the road and ground surface and along the kerbs, until it enters an underground stormwater system via sumps. The natural gradient of the street and the street and kerb design levels dictate how stormwater can be managed and where it flows. This needs careful design to ensure the construction and ongoing maintenance costs of the stormwater system are appropriate. It also needs to be carefully planned so it is free from other underground services e.g. sewer or water pipes. If new underground piping is required, this requires excavation to install it. This becomes an important consideration in a street like St James Ave, if for example a kerb build out is added to protect a tree. If, in this situation underground piping is required to manage the stormwater around that kerb buildout, then the amount and location of excavation required to install the underground piping may damage the roots of the tree, which may negate the reason for installing the buildout in the first place.

The financial cost of the Street Renewal project. There is a defined budget allowed to complete this street renewal project and one of the objectives is to complete the project within budget. The types of designs considered and extent of work to be done will need to able to be achieved within the allocated budget. This budget has been set in conjunction with the works approved in the LTCCP, and is defined to be affordable and keep rates rises within the bounds stated by Council.

The impact of any design needs to be appropriate for the classification of the street and the road users. Road users include vehicles, pedestrians, cyclists and people parking on the street. Many of the road users may not necessarily live on this section of St James Avenue, however the proposed design needs to cater for their needs within the requirements of the local road classification.

The impact on parking is an example where local residents may have different views and needs from many of the current road users who park on the street. E.g. A residents view may be that they want some on street parking for visitors, tradesmen, a spare car etc... Or maybe they don't need any on street parking as they have plenty of off street parking available on their place. They may also not want people parking all day outside their house as it takes up the available parks for their visitors, tradesmen etc... A commuter who parks there all day may want free unrestricted parking. A person who visits the park may want free unrestricted parking by the park entrance so it is easy and convenient for them to park close to where they want to go.

The project team has completed some parking surveys to understand the demand for parking along this street. An initial observation is that a number of people park close to trees and driveways. The current design standards and arboriculture advice suggest that vehicles should not be parking within 1.0m of a driveway or within approximately 2 to 3.0m of a tree. If these standards were applied to the current situation, the downside is that there would be a significant reduction to the amount of available parking on St James Avenue, whilst the upside is that there would be less damage to the trees, through less trunk damage from cars hitting the trees and less soil compaction over the tree roots, and there would be improved entry and exit to properties, with improved visibility and reduced obstructions near driveways.

Trees - the project team arranged for an independent arborist report on the trees in St James Avenue. This was completed by Paul Kenny, from Paul Kenny Contracting in Tauranga. Mr Kenny holds a diploma in Arboriculture from the Waikato Institute of Technology. This qualification specialises in the identification, diagnosis and treatment of hazard trees including tree health and tree structure, tree maintenance and management. Mr Kenny is specialised in the inspection and analysis of hazard trees and tree biology. This report recorded the condition of the trees at the time the assessment was completed. Copies of this report will be available at the workshop.

Potential construction issues to trees/tree roots. The main issue when working around existing trees is to understand the amount of excavation required in the vicinity of the trees, the likely impact this can have on the root systems and the ability for the trees to recover given the required excavation/disturbance to the root systems.

There are various construction techniques that can be used to minimise the amount of potential damage to trees when excavating around tree roots. These include ensuring arborist supervision of works, hand digging, caring for exposed roots, careful excavation and/or removal of existing kerbs and/or surfaces, reducing soil compaction, etc.... The Council staff involved with this project have recent experience with many of these techniques and, as part of the development of this project, will consider how they can be best applied to potential design options for St James Avenue.

Overhead services. Advice on the overhead services i.e. power wires, phone lines etc... has been sought and the options discussed for the existing overhead services. Undergrounding is not being considered as there is no funding available for undergrounding. Other options like cable bundling were also investigated. The initial comments are that the existing overhead services should remain, as any changes may cause more damage to the existing trees, and there are no benefits to change from the existing overhead services. In saying that, some minor alterations to the existing overhead services may be required to meet the regulations for separation distances between wires and trees. This could include a combination of some alterations to the wires e.g. using wider spreader bars and some tree pruning.

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