Sunday, 14 January 2018

Kerb Your Enthusiasm: Bus Stop Accessibility

I'm currently doing a lot of thinking about kerbs. This partly because I am obsessed with them (they are bread and butter for highway engineers) and partly because I am starting to write a guide on their use.

The guide will be published through City Infinity in the coming few months, but in the process of undertaking some research, I thought it would be nice to concentrate on how kerbs can be used at bus stops. This blog is a kind of follow up to my first kerb blog post which has also spawned one on stepped cycle tracks; plus it helps me get my mind back into writing about details rather than some of my ranting of late. 

So, why are we interested in kerbs and bus stops first off? Well, modern buses are low floor and that means that the majority of the lower deck will be at a single level to enable people using wheelchairs and pushchairs to access services and the floor of the bus is also as low to the ground as possible. Actually, most people will zero in on wheelchairs and pushchairs, but as is always the case with accessibility, improvements for those who need them most will be of benefit to everyone, so low floor buses are good for visually impaired people, people who use sticks or other walking aids and people with balance or dexterity difficulties.

Having low floor buses is one thing, but in order for them to be accessible, the bus stop environment needs to be compatible with the vehicles. From a kerbnerd point of view, this means setting the kerb height correctly to be compatible with low floor buses. In practice this means the kerb in the passenger loading area is probably going to have to be set higher than is usual. The nominal kerb "face" we use generally will be between 100mm and 125mm; this is to say the amount of kerb sticking up above the surface of the carriageway. The aim is to have the threshold of the loading door(s) to be within 200mm of the kerb.

In Inclusive Mobility we are recommended to consider using 125-140mm kerb faces, although in some cases, something a little higher might be appropriate. This guidance is a little long in the tooth in part and while it hasn't been updated, bus technology has been and if a kerb is too high, then it could create compatibility issues with the vehicle. As well as having step-free lower decks and low floors, modern buses will also have suspension which can "kneel" - to drop the whole vehicle down and a wheelchair ramp which can be deployed from the front door if single door operation, or rear doors if two door operation (bendy-buses will generally have three doors, so the centre doors in that case).

Here is a video (not mine) of a wheelchair ramp being deployed;

There are suppliers of special kerb units with perhaps the most common being the Kassel kerb from Brett Paving which comes with 160mm faces where kneeling buses are used or 180mm where they are not. Increasingly, the 180mm version is becoming obsolete with the most modern bus designs.

Above, is a photo of a Kassel kerb insitu. It's a short length and so will be used for single door operation. Note the textured top surface to reduce slip risk and the curved profile to the area between the flat part level with the carriageway and the upstand (which is raked back away from the vertical). The photo below shows a longer kerb length which would enable multi-door buses to stop (and multiple buses).

To show there is no bias, Marshalls also produce a bus stop kerb which comes with a separate channel block. Used together, the height of the kerb can be varied to fit the local requirements and the channel block has bumps to help guide the bus driver into the correct position.

We don't have to use special units as the standard half-battered kerb does a fine job. Even though we generally use them between 100mm and 125mm, they can be laid to give a nominal 140mm upstand with ease. Indeed, that has been the choice for years in my day job where we have upgraded a few bus stops to be fully accessible!

Making a bus stop is not just about the height of the kerbs. A crucial element is for the bus to be able to be driven tight into the stop in the first place - a bus stopped way out from the kerb is simply no good. To keep the stopping position clear, we are going to need a parking restriction of some kind. The best answer is to use a "bus stop clearway". This has a wide yellow line along the edge of the carriageway and a dotted yellow line marking out a long rectangle; often called a "bus cage". The layout of a bus stop clearway is prescribed in the Traffic Signs Regulations & General Directions 2016;

For a bus stop clearway to be enforceable, it needs to have an upright restriction sign which is a familiar black writing on a yellow background, also a traffic sign prescribed in the TSRGD16. Interestingly, however, bus stop clearways do not require traffic orders, although the Department for Transport suggests that consultation should take place before a decision is taken on their introduction;

The "clearway" restriction means "no stopping" except buses and taxis (not minicabs) for boarding alighting. Therefore, they can be controversial if installed outside homes and businesses because of complaints about parking and loading impact; however something has to be prioritised and a bus stop without a clearway is more likely to be abused by drivers.

The photo above shows what happens if there is no clearway. The red car is stopping the bus driver getting close to the kerb and they cannot pull far enough forward to have the rear door adjacent to the high kerb of the stop. The dropped kerb to the driveway access means that there is no way the driver can deploy the wheelchair ramp from the rear doors with a low kerb.

The photo above shows a clearway in action. Note the position of the bus stop sign (known as a "flag"). The flag is often arranged to help bus drivers stop in the right position which is with the front wheels of the vehicle in line with the flag. This means the front doors will be within the area of the shelter (if one is provided). Sometimes the stop will be arranged so the front or rear of the vehicle will be stopped in line (for a localised reason) and these are known as "head stops" and "tail stops" respectively.

You will also note from the photograph that the stopping position is towards the far end of the stop and the clearway is quite long. The reason for this lies in the steering geometry of buses with two door operation in that they require a longer distance to pull into the kerb (at a gentle angle) to ensure both doors are close to the footway. Pulling away from the stop requires less space.

The photo above shows the original kerbs have been reset to the correct height and a long enough section has been adjusted to comfortably deal with the bus driver not having to be perfectly accurate in the stopping position. The stop area has also been repaved to ensure it's nice and flat and in the future, it will show the "accessible area" within which dropped kerbs should not be placed - often an issue in urban areas where people want a dropped kerb to serve a driveway or where a developer fails to consider the needs of bus passengers in their design.

It's not just about the kerbs of course, but luckily, Transport for London produced an excellent update to it's bus stop design guidance last year which I'd recommend you read for a comprehensive explanation of the subject.


  1. Nice post Ranty, can I ask what the penalties tend to be for non compliance by motorists in the bus clearway?

    1. It will vary across the country - IIRC London is £130, but £80 if paid quickly; other English cities are much cheaper

    2. Ta, that's got to hurt, surprised they do it so much, lack of enforcement I suppose.

  2. Up here on Merseyside and parts of Wrexham bus lay bys have been filled in and the bus stops parallel to the kerb, a lot easier for the driver to stop and start from , with little time wasted in waiting for traffic to clear.Also safer for us cyclists as some idiot in a car is not going to use the layby to park in usually by overtaking a cyclist and sudenly swerving in to the lay By

    1. That's generally the aim these days, unless the speed limit is 40mph and above - much easier to get in and out; plus laybys need to be huge if 2 door buses are using them!