Obstacles in the Carriageway

Technical Information Note 31

September 2012

Photo:Ted Dewan

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© Sustrans March 2012Registered Charity No. 326550 (England and Wales) SC039263 (Scotland)VAT Registration No. 416740656Issue level: 01Owned by: DIY Streets ManagerContact: finlay.mcnab@sustrans.org.uk

All photos by Sustrans unless noted otherwise

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Introduction

Unprotected features, or ‘obstacles’ in the carriageway have always been present in our streets (see examples) and are increasingly designed into new streets.

Often these features perform a functional role, shepherding vehicles in a particular direction, reducing forward visibility so as to calm traffic and in some cases deterring parking.

They act in much the same as conventional highway street furniture like bollards or traffic islands. If they are damaged they are repaired in the same way as a conventional item would be.

However, they can also help to convey a sense of place, be it through trees to create a verdant character or a monument to create a landmark in the town square.

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7 8 91. Ashford Ring-Road2. Harlow, Essex3. Harlow, Essex4. Staiths, Gateshead5. Montpelier, Bristol6. Falkirk7. Clapton Terrace, Hackney8. Sheffield9. Petersfield, Hampshire

Photo:Graham Paul-Smith

Photo:Robert Huxford

Photo:Phil JonesPhoto:Dan BlackPhoto:Adrian Halliday

Photo:Graham Paul-SmithPhoto:Graham Paul-Smith

Photo:Andrew Fraser

National Street Design Guidance

Produced by the Department for Transport, Manual for Streets (2006) superseded Design Bulletin 32 and its companion guide Places, Streets and Movement. It is the design standard for lightly trafficked residential streets.

Design Manual for Roads and Bridges (DMRB) is the standard for Trunk Roads and ‘is not an appropriate design standard for most streets, particularly those in lightly-trafficked residential and mixed-use areas.’

In Section 7.4, page 88, of Manual for Streets, guidance is given on achieving appropriate traffic speeds. It highlights a number of approaches to reducing vehicle speed. These include:

• physical features to create vertical and horizontal deflection, • street dimensions - narrower streets - keeping lengths short betweenjunctions• reduced forward visibility • psychology and perception

In terms of the last category, Psychology and Perception, it says ‘street features and human activity can have an influence on the speed at which people chose to drive.’

It further states, ‘Research* suggests that features likely to be effective include the following:

• edge markings that visually narrow the road• reduced carriageway width• obstructions in the carriageway• features associated with potential activity in or close to the carriageway • pedestrian activity

The use of features such as trees and planters in the carriageway could achieve one or more of the above outcomes. For example, two community made and maintained tree planters at the entrance to a residential street can form a visual and/or actual road narrowing, create horizontal deflection, reduce forward visibility and, through the bespoke character and style of the interventions highlight the presence of people and likely pedestrian activity.

*J Kennedy, R Gorrel. L Crinson, A Wheeler, M Ellliot, (2005) Psychological Traffic Calming TRL

Report No. 641, Crowthorne.TRL.

Photo:Phil Jones

Photo:Graham Paul-Smith

Photo:Andrew Fraser

Addressing Concerns Obstacles are not allowed

because they obstructthe highway

What if a vehicle hits it? The Traffic Signs Manual

and DMRB require 450mm clearance for vertical objects

back from a Kerb

The Highway Act 1980 states:

‘137 Penalty for wilful obstruction.. If a person , without lawful authority or excuse, in any way wilfully obstructs the free passage along a highway he is guilty of an offence and liable to a fine‘

This piece of legislation is aimed at members of the public - ‘if a person’, rather than the highway authority. Highway authorities place ‘obstructions’ in the highway all the time, e,g, for traffic calming, signage, traffic islands etc.

It should also be noted that simply placing an object in the carriageway does not necessarily cause any obstruction to free passage. Tracking can and should be done to ensure vehicles are able to fit between and through obstacles. Also, objects can be shielded by other objects such as a build-out or parked cars (see below).

Won’t we be liable?

Traffic Signs Manual (6) states

1.48 Signs should be set at least 450mm from the edge of the carriageway.

Design Manual for Roads and BridgesTD 50/04 THE GEOMETRIC LAYOUT OF SIGNAL CONTROLLED JUNCTIONS AND SIGNALISED ROUNDABOUTS states

2.39 Adequate clearance between the edge of carriageway and any street furniture (including signal heads, backing boards and subsidiary signal heads) is needed to prevent damage by vehicles having a lateral overhang. A minimum clearance of 450mm should be provided.

The Traffic Signs Manual is guidance and the relevant section in the DMRB is not highlighted as a statutory section.

In any case, this guidance is focussed on the placement of auxiliary street furniture e.g sign posts and guardrailing. Whereas, the obstacles as described in this note could and are designed as the traffic calming features themselves. In many ways, they are functioning in the same way as a kerb build-out. The fact that they are non-typical features and have a sense of vulnerability and risk to them serves to add to the ‘psychological’ traffic-calming effect.

Highway Authorities shouldn’t get locked into a risk management mentality:

‘The objective of the Highway Authority is to obtain the maximum benefits for the community. It is a task that is wholly different to that of minimising risk’

Highways Risk and Liability Claims, Institute of

Civil Engineers (July 2009)

What happens when someone knocks over a bollard? It gets fixed or replaced. The same happens when a planter gets knocked.

The advantage of a relatively low-cost free-standing planter (£200-£500) is that it doesn’t cost the earth to fix or replace - no excavation or surface works are required. Certainly, it is similar to the cost of replacing and re-fixing a bollard.

When you consider the up-front cost of conventional traffic calming such as kerb build-outs and speed bumps the economic case is stronger still.

A further benefit, is that if a free-standing obstruction like a planter is regularly being hit, it is relatively easy to move it or adapt the design. It offers flexibility. By contrast, a fixed traffic calming feature like a kerb-build or a speed bump is relatively expensive and difficult to move once it is in place.

‘Highways Risk and Liability Claims’ (Institute of Civil Engineers, 2009), highlights two important principles established in case law:

• The road user has a responsibility to take the road as they find it.

• The road user has a responsibility for keeping a lookout for obstructions.

Demonstrated by the judge’s statement in Gorringe v Calderdale (2004):

The “overriding imperative is that those who drive on the public highways do so in a manner and at a speed which is safe having regard to such matters as the nature of the road, the weather conditions and the traffic conditions. Drivers are first and foremost themselvesresponsible for their own safety” (Lord Scott at para 76

“My Lords, the general rule is that even in the case of occupiers of land, there is no duty to give warning of obvious dangers: see the recent case of Tomlinson v Congleton Borough Council [2004] 1 AC 46. People must accept responsibility for their own actions and take the necessary care to avoid injuring themselves or others. And a highway authority is not of course the occupier of the highway and does not owe the common duty of care.”

How will it affect drainage?

One of the advantages of free standing obstacles in the carriageway is that they need not impede drainage channels or require a re-alignment of the kerb line. As such, they have a significant cost saving over conventional traffic calming approaches.

How will people see an object at night or in poor visibility ?

There are several ways to make ‘obstacles’ in the carriageway more visible at night.

These include using reflective products and materials, such as ballotini glass beads or reflective strips.

Ballotini glass beads painted on to planter - if applied correctly they have been shown to have more luminosity than a typical street sign.

Photo: Ted Dewan

Case Study: Beechcroft Road, Oxford (completed Summer 2010)

Beechcroft Road was a busy cut through in a residential area in Oxford. It suffered from inappropriate vehicle speed and inconsiderate pavement parking.

The council offered residents the opportunity for speed bumps to calm traffic. However, the residents felt that this would not address the underlying issue of inconsiderate and inappropriate driver behaviour in the street. They felt drivers would simply slow down to go over a speed bump and then speed up again, probably with an increased sense of frustration. They wanted drivers to realise they were passing through an area where people lived, where kids might be playing or older people walking and therefore drive more appropriately and with respect for the place.

They developed a design in collaboration with the council and Sustrans which included a painted pattern at the centre of the street, several free-standing planters and an on-street cycle rack.

Before

The re-design was completed in summer 2010 and continues to be a great success. Average speeds are down from 21mph to 16mph and two years later none of the planters have needed to be replaced or repaired. A couple have been nudged by reversing cars but because of the fibre glass construction have not been significantly damaged. The planters ‘present’ as stone and it is thought that this discourages drivers from getting too close to the planters and creates a psychological traffic calming effect.

Two years on, community champion, Ted Dewan reports that the whole atmosphere on the street has completely changed with drivers taking much more care and consideration. He feels that as the planting has become more mature this has made damage to the planters less likely because they are more visible. They have also added to the traffic calming effect because they have a greater presence in the street, are more of an obstacle to navigate past and are more effective at reducing forward visibility.

Pictures from August 2012 (approximately two years after completion)

On-street cycle ‘bespoke cycle rack’ (which remains undamaged)Before

Creative use of reflective Ballotini glass beads (as designed by the children on the street) contribute to a special sense of place and warn drivers of the obstacles at night or in bad light.

Case Study: Ellacombe Road (completed Autumn 2009)Ellacombe Road was a busy cut-through in a residential area in Torquay. It also suffered from excessive commuter parking. Torbay Council put the street forward to be part of the pilot for the Sustrans’ DIY streets project which helps residents to re-design their streets to make them safer and more attractive.

The final design saw the introduction of a one-way system with ‘gateways’ at each end, chicanes and a change in parking orientation to an ‘echelon’ layout. However, rather than using a conventional highways palette, a bespoke planter was designed using railway sleepers and masonry. No kerb upstand was provided as protection. The planters were then filled with plants by the residents which helped to create a verdant street character.

The scheme opened in Autumn 2009. In the following months, the scheme was kept under close supervision. Two out of the eight planters (close to a pub car park) were knocked a few times and required repair - the others were unaffected. Therefore, reflective strips were placed on all the planters to help drivers see the planters at night. In addition, a single bollard with a reflective strip was placed next to the two planters which were being hit. There have been no further issues .

Before

Bespoke gateways convey to the driver that they are entering a ‘special area’ and need to drive carefully

Photographs below are taken in October 2011 (two years after completion)

Above: Reflective strips warn drivers of the obstacle.

Left: A few months after completion, a single bollard was placed next to the planter which was being knocked to give it more protection. This wasn’t required for the majority of planters.