The draft developed for a car free city area is tuned to a specific urban development
to a great number of specific and actually valid policy prerequisites and technical limiting
conditions. This raises the question to what extent the car free city area concept is
applicable in broad outlines.
The following aspects should be considered:
* size required for a car free city area.
* siting of the car free city area.
There are no technical limitations to the size of a car free city area. However other factors influence the minimum required size:
* costs aspect
* urban development limiting conditions
* enforcement car free character
An essential element in the concept developed for a large car free city area is such a management system as to keep out private car traffic from the city area and to maintain at an absolute minimum level the remaining motorized traffic. It cannot be left to social control to achieve this. Making car traffic impossible by a completely successful roadway infrastructure has the disadvantage - certainly in a somewhat larger area - the area is no longer accessible to emergency traffic and other servicing traffic. Even advanced technical expedients fail to "filter" motorized traffic without undesirable side-effects.
For these reasons two manned city area entrances are chosen which add up to a large cost item of about fl 445.000 per annum. Financing these fixed yearly costs is possible from saving on inter alia land costs. On the basis of a return of about 6% a capital of 7,4 million guilders would be needed to cover these fixed charges.
If also 3 to 4 million guilders are to be put aside to optimize the car free city area the saving has to be at least 11 million guilders.
The verified draft of 5600 residences yielded up to 16,5 million guilders in saving. As the saving is directly proportional to plan size, in this case the number of residences, the minimum number of residences required would be 5600 x 11/16,5 = approx. 3700.
This plan size still requires two manned entrances also. For one manned entrance to suffice beside the plan size also urban development and locally determined requirements must be taken into account.
This is pursued further in chapter 4.3.
One manned entrance requires relatively more staff than two entrances to dispose of a sufficient reserve in case of sickness and holidays.
Assuming 4 staff members the fixed charges are:
* fl 240.000,- :salaries
* fl 40.000,- :organization/administration/overhead
* fl 15.000,- :6% maintaining costs technical systems
total fl295.000,- fixed yearly charges for one manned entrance.
These fixed charges require a capital of nearly 5 million guilders. Together with 2 million guilders for optimization measures saving of 7 million must be reached which require a plan size of 5600 x 7/16,5 = 2350 residences or a plan size of 40% of the developed plan. It is however to be doubted if for such a size one manned entrance suffices.
From the foregoing may be derived the minimum planned size is about 3700 residences applying the concept used of a car free city area and on the condition of budget neutrality between a traditional plan and a car free city area.
In case of such favorable residence construction location siting and layout one manned
suffice the lower limit of the minimum required plan size is still about 2300 residences.
It has to be observed the fore-mentioned numbers of residences are calculated on the basis of saving the car free plan yields in respect of the "base plan". However this base plan probably offers a more favorable plan exploitation than the so called "traditional plan". This may be derived from the differences between the base plan and the traditional plan in regard of land use .
In other words: if budgetary neutrality would be related to the car free plan in respect of the traditional plan from a cost point of view minimum required plan size will be smaller, about 3000 respectively 2000 residences.
These data are only a cautious estimate as calculation of land costs in the traditional plan has been omitted because of the impossibility to establish a representative average cut comparable to the base plan.
If budgetary neutrality is not pursued and/or a smaller part of saving is reserved for optimization measures, the minimum required size may be further reduced.
If it is decided to abandon manned entrances to keep out (non admissible) motorized traffic other means are necessary to enforce the car free character. The most simple method is rendering impossible any kind of motorized traffic in a city area:
no parking facilities (except at the fringe for visitors) and to motorized traffic permanently closed off residential streets.
The layout of such a residential area should be so, emergency traffic may reach
residences within an
acceptable distance (50 to 75 meters). Most efficient (and theoretical) configurations are
given in figure 48.
In such a manner plan size of 100 to 400 residences is feasible at an average residence density of 60 residences per hectare.
However such small car free neighborhoods may only function under the following conditions:
* Plan size is not large enough to have facilities "of its own". This means schools, shops and the like have to be at walking and cycling distance and must have a direct public transportation line with the neighborhood.
Therefore the car free neighborhood must run into other built-up area and must also be favorably situated in respect of facilities.
* To prevent the car free neighborhood to be inhabited by car owners parking their car in the visitors parking lot or in a neighboring built-up area, the granting of residences in the car free neighborhood must be to non car owners.
It could be a problem to find a juridically and socially manageable format.
* Small car free neighborhoods must be situated directly at stops for public transportation.
The public transportation application intensity in a small car free neighborhood of 100 residences can be calculated as follows: (using the same premisses and quantities as in the research location)
100 residences and average occupation 2,5 = 250 inhabitants
number of movements per inhabitant = 2,8
number of total movements = 700
number of public transportation movements = 33% = 231
number of movements between 7 a.m. and 7 p.m. = 80% = 184
bus frequency : in each direction one per 30 minutes
number of bus stops (in two directions) : 12 x 2 x 2 = 48
average number of persons boarding per stop : 184/48 = approx. 4
Presumably the average number of persons boarding per stop will be larger, because public transportation will also take part in movements to school and to daily facilities.
As to the size of car free (or car free) residential city areas the following may be concluded:
* For residential city areas on a larger scale where personnel input is required to enforce the car free character the turning point for budgetary neutrality lies at about 3000 to 3700 residences.
Below this number of residences the saving in most cases does not offset the investments and fixed charges needed for the car free character.
* For smaller residential city areas not the costs but the urban development, functional and managerial conditions are determining feasibility.
For a plan size of more than 300 to 400 residences the proximity (and accessibility) of public transportation stops and facilities may become a problem.
Also the residential neighborhoods become too large to keep the residences at an acceptable distance from provisioning and collecting points of servicing traffic. For emergency traffic the accessibility of residences and residence-blocks becomes a problem too.
Besides the check (also social check) on unauthorized car ownership becomes more difficult as the size of residential neighborhoods increases.
* Residential city areas having a size between a few hundred and approx 3000 residences constitute a difficult category. Too small to finance an adequate enforcement of the car free character from saving, too large for a more passive enforcement policy and related functional and urban development limiting conditions.
For siting some kinds of coherent conditions are of importance:
* sufficient interest i.e. an appropriate marketing profile
* appropriate urban development and functional conditions
It is not inconceivable the interest to live in a car free city area is related to population density.
Perhaps in relatively sparsely populated areas car dependency may be stronger and confrontation with car mobility problems will be less. Therefore it is possible at decreasing population density not only the reservoir of potentially interested persons decreases but also the proportional number of actually interested persons.
This means in more sparsely populated regions only larger towns will offer appropriate conditions to establish car free city areas of some size.
The population density depends in its turn on functional conditions. In general public transportation density and frequency are lower, while distances (education, regional center-facilities) may be larger. Substitution opportunities between car and other transportation modes may be smaller.
This also indicates in less populated regions only the larger cities offer suitable limiting conditions for car free city areas of some size.
The urban development conditions especially refer to siting of a car free city area in relation to the urban body of which it is a part. In principle a central location is most appropriate. In the city centers public transportation is best developed: most kinds of public transportation (busses/trams, trains, taxis and the like), most directions and highest frequency.
Besides an abundant supply of facilities is available and the preference of interested persons (see chapter 6.5) also is to live in a central location in the city.
Urban restructuring areas offer starting points for realizing a car free or car free environment.
The same is applicable to urban renovation areas where technically speaking no impediments need to exist for introducing a car free environment.
It may however be problematic how to tune the residence pattern to non car ownership and how unauthorized car ownership (parking in an adjacent area) may be discouraged.
Larger construction areas are predominantly situated on city fringes. Within this data in locating a car free city area it is important to pay attention to:
* vicinity of major shopping centers which have to be well accessible to public transportation and low velocity traffic.
* very good public transportation connections with important junctions of the interurban public transportation network (busses, trains) and/or the vicinity of so called transfer junctions.
* the possibility to approach the car free city area from several main directions.
* Filling up "wedges" between existing urban areas would be the most ideal location but this may come into conflict with existing land use (sports fields, parks etc.)
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