The Parish or District Council will need to take on the future maintenance of these features under licence depending on what features it includes, e.g. planting or planters.
Things to consider
Other traffic calming works may be combined with a gateway, these could include pinch points, buildouts, islands, and rumble devices, together with changes of carriageway colour and/or texture and the use of appropriate signing. Where changes in the surface of the carriageway are used it will be most effective if they start at the gateway location, rather than in advance of it. This helps to give greater prominence to the gateway itself.
Most speed reduction achieved by a gateway treatment can be extremely local and may be eroded over time. To achieve the most beneficial effect, other traffic calming features will have to be located close to the gateway and extend over the length of road over which the speeds need to be contained.
Gateway features cannot be used to prevent access, so therefore both the horizontal and vertical elements of the gateway must be constructed so that it can be negotiated by any vehicle entitled to use the road.
To achieve the maximum speed reduction possible the gateway must be conspicuous and within any aesthetic constraints imposed by the location, and colours should contrast with the surroundings. Should a coloured surfacing be considered, or rumble strips or markings from an on- carriageway perspective, then the area should normally be at least 5m in length, so it is clearly visible from a distance. Longer lengths up to 10m can improve conspicuity but beyond this may detract from the effect of the gateway. Edge line markings, such as ‘Dragon Teeth’ can make the gateway appear narrower than it is whilst still allowing larger vehicles to overrun these areas if necessary.
A gateway needs to be sighted so that drivers do not encounter them suddenly as this can be hazardous and may not bring about the desired reduction in speeds. The gateway will need to be visible over at least the stopping distance for the 85th percentile of the approach speeds. Basing the distance on the current speed limit will often not be sufficient and speed survey measures will be needed to identify the 85th percentile. Site inspections will confirm whether the stopping site distance is sufficient.
Physical measures, such as buildouts, chicanes and pinch-points can also be used as a narrowing effect and enhance the effect of the gateway and to reduce overall carriageway widths. Islands will need to be appropriately signed and sufficient lane widths retained to suit all vehicles likely to use the gateway. Where farm equipment or specialist commercial or military vehicles have to negotiate a gateway, it can be helpful to use ghost island markings or overrun areas.
A gateway feature comprised of vertical features alone is unlikely to influence vehicle speeds. Where a reduction in speeds is being sought it is recommended that gateways are used in conjunction with horizontal elements. When choosing the location of the gateway there is a need to ensure there is sufficient width to accommodate the vertical elements and that sufficient set back from the edge of the carriageway is available to ensure vehicles cannot come into contact with them. The location of these elements in a footway or cycleway path should be avoided unless there is sufficient space remaining to allow the safe and convenient passage of pedestrians and cyclists and provide sufficient headroom.
Vision Zero Considerations: Many road users each year die because they hit objects after they have left the carriageway. Examples of features which have led to a death include trees, telegraph poles, sign poles, ditches, ponds, wooden fences, embankments etc.
- We must therefore ensure that any features are essential and are protected or passively safe to ensure they do not create risk.
- We must ensure that we do not introduce features that cannot or will not be maintained and that we do not introduce features that will be obscured by vegetation.
Motorcyclists are the highest risk group, comprising about 2% of traffic but 25% of DSIs and they require more protection. Many are young riders in urban areas who could be protected by lower speeds, better road/place design and less street clutter, others are more susceptible to poor surfaces including debris, inspection covers, unlit obstructions such as central refuges and unprotected signposts.
- Each person involved in each scheme, from the scheme promoter to the designer to the constructor needs to ask themselves what impact the scheme will have on the risk to all users but especially riders.
Costs and timeframes
The design and installation costs of gateways are dependent on the types of measures that are going to be used so it is not practical to be able to give an indication of cost until all the details are known. This also applies to the design and construction durations as this is also subject to the interventions being considered.
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Design
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Constuction
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Fee
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Duration
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Cost
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Duration |
Gateway Features |
To be determined scheme by scheme |
The design duration is measured from the point in time where the scheme has been commenced by the allocated Engineer. The construction durations include the minimum mobilisation time required to provide sufficient time to process the works information and mobilise personnel to undertake the works.
Where a TRO receives an objection additional cost, and time will be incurred on the scheme to either remove the objections through consultation with the objector or for a CMA to be processed. These costs and timescales are dependent upon the number of objections received.