I am looking at these together as they are essentially the same; an entry treatment represents the point where traffic turns into a side road which may or may not have contiguous traffic calming, whereas a gateway does the same but without the junction, i.e. all traffic is invited to cross the threshold into, or out of, a speed control zone. So do they work?

Gateways

Much has been said and written about gateways and in many senses drivers have been entering them in sign form for many years. Most authorities have been linking up village place name and speed limit signs, and in tourist areas they often make a delightful rural feature of this with flowers, planting, or just mounting the village name plate on a plinth or Mill Stone as is so often seen in the North of the UK.

Further techniques have been tried including placing an island in the middle of the road so that drivers see three speed limit roundels and the layout may include a roundel marked on the carriageway too. Drivers are in no doubt that they are entering a speed restricted road. But do they work?

The evidence from a number of studies suggests that they have an immediate effect which wears off relatively quickly. In the urban or village environment there is often too much to be thinking about and unless there are other reasons for drivers to slow down, or they are positively thinking about it, their speeds can continue to be higher than they should. But at least there is no excuse from the enforcement point of view. Nevertheless there is currently a major question about the gateways that we currently have up and down the country with reports of little speed change other than at the point concerned. So they need to followed up with other features.

Vertical deflections at gateways

Until July 1996 a gateway could not incorporate any form of vertical deflection unless there was a form of speed restraining feature in the geometry of the layout. The deregulation of traffic calming now allows the use of vertical deflections on roads with a speed limit of 30mph or less provided that the scheme is well lit. But I have yet to see a gateway with a vertical deflection incorporated into it.

But there is no reason why a gateway should not have a shuttle incorporated; I have seen many gateways where the carriageway is narrowed but not so that traffic has to shuttle work. I mention in my chapter on pinch-points and shuttle working that while there may be more than one reason to slow down, if drivers have a very good view for over about 100m beyond the pinch-point then they may be able to assess whether they can take their right of way too soon before arriving at the control point and thereby race for it. I feel that a better way of controlling speeds is to incorporate a speed table or cushion(s) into the gateway with or without a central island, but I accept that there will be cases where a shuttle working gateway will be quite acceptable, and if there is intended to be a priority system then traffic leaving the restricted area will normally have the right of way, and do use the full set of give-way markings with the signs. I recommend you use a central island prior to the gateway to create a slight chicane and to mount additional signing.

It is important that your gateways are attractively designed. The CPRE has recently come out somewhat against them on account of the large garish signs that are often used; careful landscaping in accordance with local custom and materials will help to overcome these concerns.

Entry treatments

The main purpose of the entry treatment is to give a clear message to drivers that they are now entering an area where speeds are expected to be well controlled and pedestrians and cyclists can be expected to mix safely with the traffic generally. Because the vast majority of entry treatments occur at side-roads of very much lower status and traffic volumes than the main roads which they join, they often have some form of vertical deflection incorporated in them if only to enable pedestrians to cross the junction at grade and so eliminate kerbs, even the few millimetres that are usually left at drop kerbs. The danger of course is that drivers may overrun onto the pedestrian only area so posts or other features are often incorporated to prevent this.

Entry treatments can be difficult for drivers entering from the main road as they are under more pressure to give way to pedestrians while at the same time there may be following traffic that may not wish to stop. The best entry treatments are those on roads which have wide main road footways or where verges separate the main carriageway from the footway so that there is usually about a car length between the give-way/edge line at the junction and the pedestrian crossing point on the top of the ramp.

Some entry treatments are narrowed to single track working and this has been recommended in some cases even where two-way traffic flows into or out of the side-road. I would recommend avoiding this arrangement as there will inevitably be occasions when drivers meet on the junction and one vehicle may have to reverse onto the main carriageway. Where your side road is one-way "in" or perhaps one-way "out" (exit treatment) then you have the opportunity to make the pedestrian passage across the road as narrow as 3m and if the main road is a dual carriageway or traffic has to turn left then the geometry of the arrangement can and should reflect this.

So much for the side-road, but what about main road traffic calming?