Urban Update 7 Jan 2016

Download Urban Update 7 Jan 2016

 

Look to the hills to prevent urban flooding

Is it possible to deal with flooding at source?  Local urban flood defence schemes can have a significant visual impact that destroys the value of a river frontage.  In Dumfries,3.5 metre high flood defences are needed to protect White sands area of town from a 1 in 75 year river levels.  The standard option would be to create a 3.5 metre high earth bund. Careful redesign involving the community has resulted in a £15 million proposal using reinforced glass panels and demountable barriers that reduces the height of the bund to below eye-level.  

Details of scheme  http://www.dumgal.gov.uk/index.aspx?articleid=12392

Google Street view  http://bit.ly/1mHSIQX

Even so – is protection from 1 in 75 year flooding adequate, especially now that climate change may be changing rainfall intensity.   Should other or additional means to reduce flood risk be found?

The Independent has observed that while York has been heavily flooded, despite conventional flood protection schemes, nearby Pickering escaped…. and the reason is the Pickering Slowing the Flow project which has sought to reduce run-off in the entire river catchment above the town.  It has included:

·         Construction of large woody debris dams

·         Construction of timber bunds

·         Blocking moorland drains and controlling erosion

·         Establishing no-burn buffer zones in the heather moorland.

·         Planting riparian and floodplain woodland

·         Planting farm woodland

·         Amending forest plans and restoring streamside buffer zones

·         Implementing farm-scale measures

·         Construction of low level bunds

Full details:

http://www.forestry.gov.uk/fr/slowingtheflow

The report highlights the Reservoirs Act as a significant problem. It imposes a design orthodoxy that favours single heavily engineered dams that are designed to 1:10,000 year events, rather than successions of very small dams right across a catchment.

If the climate is changing, and atmospheric physics predicts a 7 percent increase in 24-hour extreme rainfall for every one degree centigrade increase in temperature, then there is probably no alternative to these types of flood control measures

http://www.independent.co.uk/environment/uk-weather-why-the-recent-devastating-floods-will-become-the-new-normal-a6793291.html

 

New SUDS Manual published by CIRIA   Free to download

This 800 page guidance represents the state of the art in Sustainable Drainage Systems.  It contains of scores of examples and design ideas that can be incorporated in new and existing development.

A Introduction

B Philosophy and Approach

C Applying the approach - - the design process

D Technical Detail – detailed descriptions of different types of SuDs components

E Supporting guidance

http://www.ciria.org/Memberships/The_SuDs_Manual_C753_Chapters.aspx

What the guidance leaves is the job of putting everything together.  There is guidance for every aspect of the urban environment (apart from utilities where the guidance and legislation is deficient). The need for drainage in urban areas is often dictated by the demand for car parking; the demand for car parking is dictated by development density, the provision of public transport, cycling and walking infrastructure, and the presence of shops and community facilities that can be reached without the use of a car.  It is not immediately obvious that local shops reduce urban run-off…But they do

 

Road Test - Frideswide Square Oxford 

Short video

https://vimeo.com/150654810

Frideswide Square is a £5.8 million public realm and highway scheme in Oxford.  Public realm schemes should never be considered in isolation but taken in the context of the wider network of streets and highways and surrounding development, all of which greatly influence how road users behave.  Most of the roads leading into Oxford are ancient, narrow, and heavily trafficked, with large volumes of buses. Provision for cyclists is not ideal.  There are some streets where there are 20 mph limits, though the coverage is half-hearted. The impression is that Oxford’s streets are hostile, congested, and often unattractive.   What needs to happen in Oxford is far more than a single public realm scheme, but a major investment on all the main routes, and in new routes for cyclists, to bring them up to a standard that reflects a world class city.

Against that background however, there can be no doubt that the new Frideswide Square scheme is a huge improvement in public realm on a key gateway to the city of Oxford – Frideswide Square is the main route from the railway station to the city centre, as well as being the main road route from the west.  Traffic signals and multi-lane highways have been slimmed down, channelized, replaced with roundabouts, footways have been widened, and landscaping added, plus new generation street lighting.

The scheme differs from the ground-breaking Poynton scheme (2011) in a number of important details.

-       in Poynton, the approaches to the roundabouts/shared space are calmed by around 50-200 metres of channelized street, whereas in Oxford, drivers are likely to have been seriously wound-up by the congestion, and wound-up by the traditional negative press coverage associated with ne schemes. 

-       to naturally reduce driver’s speed, the the visual width of the carriageways at Poynton, is reduced to the bare minimum by using rows of stone cubes laid in the channel by the footways and central median.  A quadruple row of cubes is laid on the footway side, which naturally leads drivers to keep clear of the pedestrians. Using stone cubes to line channels is a traditional feature going back at least as far as the 19th century.   Omitting this feature will save money, but if used on approaches the greater visual width would also lead to higher vehicle speeds. 

-       The edge of footway in Poynton is marked by rough texture “cauliflower kerbs” which can be detected by blind and partially sighted people.  In Frideswide Square the kerbs are smooth surfaced. 

The design of the Frideswide Square  bus bays has come in for some criticism from bus operators, who claim they are too small, with concerns raised about planting.  Our inspection of the site shows that the bus bays are actually very long, and the planting comes nowhere near the carriageway.  It is true that it is easier for bus drivers to get close to the kerb in saw-tooth bus bays. But the bus companies don’t appear to have taken issue with this. Unfortunately the press reports don’t detail what the bus companies are objecting to other than safety and size.

We observed drivers were giving way to each other at the roundabouts – at no time were they blocked.  But neither did we see drivers giving way to pedestrians, though the observation period was fairly short.  In any case the central median and low traffic speeds enables sighted pedestrians to pick their time to cross between gaps in the traffic. .

It is clearly a traffic flow success, and certainly a provides a far more attractive and convivial environment for pedestrians.  For cyclists the jury is still out.  What is clear though is that Frideswide Square, together with Poynton offers an alternative to the bog standard lines signs and signals approach that blights so many towns and cities across the entire world.   

 

Let’s hope that 2016 marks a turning point in the way we design main streets and urban junctions. Out with space-hungry, multi lane signal controlled blots on the townscape.  In with broad pavements and attractive streetscapes, channelled traffic, and slow, safe, smooth movement, and plenty of space for people. 

 

Red Light District…

2015 was also the year when Beverley hit the international press for a 42 traffic light junction  which was ridiculed in the German newspaper under the headline – “Diese Kreuzung ist ein Rotlichtviertel”  (there’s a pun in the title)

http://www.bild.de/news/ausland/verkehrsbehinderung/diese-kreuzung-ist-ein-rotlichtviertel-42374616.bild.html