Thursday, June 4, 2009

Query? Whatever happened to road hierarchy?

The following open question on the present status of "road hierarchy" uses and standards for planning just in from Stephen Marshall of the Bartlett School of Planning, UCL - and right up the middle of the street (as it were) of our concerns here. Full contact information follows. You are invited to post your responses directly to him, but it would be good for all here if you could also register it just below as a Comment to this posting. We hope to report on this in due course as the results come in.

Dear all

Following Manual for Streets and other local streets-oriented design guidance, where does this leave road hierarchy?

By road hierarchy I mean the conventional set of road types such as Primary Distributor, District Distributor, Local Distributor, Access Road.

I am asking this list because it can be difficult to track how this is actually used, through published documents, since a document may not mention hierarchy explicitly, but it may still be applied in some way. Or, even if mentioned in a document, it is not always clear how practitioners actually use it, when designing a road network.

I am interested in hearing of any cases where:

(i) Road hierarchy is still used - even if not expressed explicitly in documents - if so, how is it applied?

(ii) Road hierarchy has 'evolved' where there may be new road types added over and above the basic set - if so, what are they?

(iii) There is more than one set of guidance coexisting (e.g.
conventional engineering guidance + urban design guidance) - if so, is the relationship between the two clear and consistent, and how are they actually applied in practice?

(iv) Urban design style street types are used, but are expected (implicitly or explicitly) to correspond to levels in the conventional hierarchy (e.g. a Boulevard may be equate with a District Distributor; a Mews may be an Access Road) - if so, how does this work?

(v) Road hierarchy is applied to the "higher levels" (e.g. trunk roads, county roads) while the lower level use a range of labels (e.g. access street, high street, etc.) - if so, how is the high/low level split decided?

(vi) Road hierarchy is no longer used - if so, what if anything has replaced it?

I would be interested in hearing of any examples of these instances, and how they work, especially in the UK (e.g. local authority practice), but also non-UK examples where the equivalent of road hierarchy applies.

I will let the list know of any interesting results coming out of this. This is part of an investigation into better integration / articulation of road / street hierarchy / layout principles. This research is part of the EPSRC funded project SOLUTIONS (Sustainability Of Land Use and Transport in Outer NEighbourhoodS).

Stephen Marshall, Senior Lecturer, ucftsma@UCL.AC.UK
Bartlett School of Planning, University College London
Wates House, 22 Gordon Street, London WC1H 0QB,
Tel +44 20 7679 4884, Fax +44 20 7679 7502

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