Road junction research questionnaire

[SamWolves23]

Hello all,

I would appreciate it if you could take a few minutes to complete this questionnaire on road junction design for my university research. It should take about 10 minutes and closes in a few days.

https://forms.office.com/r/w9HKhR630k

Thank you for your time

[A303Chris]

Hello and thanks for posting.

I will fill in your survey, but a few points. The first there is only one cloverleaf junction in the UK in Redditch, so most people will experience a junction such as this abroad.

The thing about how a driver perceives a junction, it is not necessary down to design but how the junction is signed at the junction and on the approaches , including road markings.

A junction when designed and built may have been able to accommodate traffic flows but over time and changes in planning policy, traffic volumes have increased and the flow is above the capacity of the junction.

Junctions, apart from free flow are not designed for speed and there is no differentiate between signalised and non signalsied GSJ's which play a part in capacity and speed.

Also your references to junctions from the DMRB have been withdrawn

[Chris5156]

I will fill in your survey, but a few points. The first there is only one cloverleaf junction in the UK in Redditch, so most people will experience a junction such as this abroad.

There’s a second one in Livingston near Edinburgh, but the point stands that they are virtually unknown in the UK and most drivers will never have seen or used one, and those that have are unlikely to have done so in the UK.

[Big L]

I got to question 4 and bailed out.

Are diamond interchanges good? Yes or no.

Not enough options.

[WHBM]

Welcome to our board. Completed.

Unfortunately you are asking complex questions reduced to a "Janet & John" small series of responses. The professionals on here will tell you there are 101 parameters to consider. Not least is whether the conflict points are signal controlled or gap accepting.

4-level stacks look like utopia for conflicts, but are extremely expensive, have considerable land take, and are a nightmare, if not impossible, to widen the main carriageways through the central structure.

Much of the safety aspect is determined by traffic flow merges, and the theory doesn't cover merging, lane gain, etc.

[JohnnyMo]

If you answer No to Can you recall encountering this type of junction -- then you should proceed to the next junction type rather than saying if it was a good choice.

What is a good choice in some places maybe really bad in others, depending on the traffic levels and balance.
Roundabouts are generally good if balanced, but put it in the wrong place & it can is appalling.

Any junction should be intuitive with good signage, even Spaghetti Junction.

I got to about question 30 before bailing out

[J N Winkler]

I concur with others' observations about whether given junctions work depending on site-specific characteristics of traffic flow, geometric design, signing, and marking; this makes it difficult to assess them by broad design category.

The last question is numbered 48, but the actual number of questions is closer to 200 if each request for a Likert-scale 1-5 rating is counted as a separate question. I'd worry about the lack of a progress indicator encouraging takers to click through just to see how far it is to the end.

[c2R]

Agreed, I gave up at around 30 - the sorts of questions that you're asking are very simplistic, but the location of junctions vary from place to place - for example, a T Junction - I've used some excellent T junctions where nothing else is needed, but there are also appalling examples that could be designed much more effectively. Similarly, while both whirlpool and four level stack junctions are good, they have different costs and benefits - whether one junction is better than another will depend on things such as geography and traffic flows.

[J N Winkler]

For a given junction type, other countries often see more of a spread in design characteristics and performance than the UK. Britain's three Maltese cross stacks (Almondsbury, Thorney, Merstham) were all built within a 20-year period after geometric design standards reached substantial maturity, and are fairly similar to one another. In contradistinction, a gulf yawns between the Four Level in Los Angeles (1954) and, say, the SuperRedTan TI in Phoenix (2007). (All links go to Google Maps at zoom level 19 so scale is uniform.)

[KeithW]

There are a couple of web pages I would suggest a well worth a visit in regard to junctions

This one gives list and description of the types of junction to be found
https://www.roads.org.uk/interchanges

There is a list of bad junctions here and critique of their design here.
https://www.roads.org.uk/badjunctions

In my area there is this hybrid type which still works well over 40 years after it was built despite traffic growth
https://www.google.co.uk/maps/@54.56296 ... !1e3?hl=en

[Chris5156]

Agreed, I gave up at around 30 - the sorts of questions that you're asking are very simplistic, but the location of junctions vary from place to place - for example, a T Junction - I've used some excellent T junctions where nothing else is needed, but there are also appalling examples that could be designed much more effectively. Similarly, while both whirlpool and four level stack junctions are good, they have different costs and benefits - whether one junction is better than another will depend on things such as geography and traffic flows.

I gave up at about 45, when I reached questions asking me “what, if any” but which were mandatory to answer. As far as I could tell I was being asked to list every dual carriageway junction I could remember.

I also felt like a lot of my answers were an arbitrary guess. How am I supposed to sensibly rate a junction for safety or peak time traffic flow if it doesn’t exist in the UK and I’m only allowed to answer from my own experience?

The diagram of a turbine interchange was interesting: it showed two exits per carriageway, but entry slips combined to make one merge per through carriageway. That variant doesn’t exist anywhere in the UK. I also found the diagrams of a crossroads and a T junction bewildering!

[M4Simon]

Agreed, I gave up at around 30 - the sorts of questions that you're asking are very simplistic, but the location of junctions vary from place to place - for example, a T Junction - I've used some excellent T junctions where nothing else is needed, but there are also appalling examples that could be designed much more effectively. Similarly, while both whirlpool and four level stack junctions are good, they have different costs and benefits - whether one junction is better than another will depend on things such as geography and traffic flows.

My sat nav once directed me to a T junction with the A1 in Lincolnshire (a dual carriageway junction so it counts), and then asked me to turn right across a busy live carriageway. After waiting a few minutes for a gap, I gave up, turned around and went another way. As all-movement T junctions go, it was very dangerous. There are some perfectly good ones on less busy dual carriageways where the junction includes splitter islands and a wider central reservation to facilitate a two-stage right turn.

I got to the end of the survey and submitted it, but it is very subjective depending on whether the examples you think of are good or poor. However, it is about public perception rather than objective research into junction types so I guess it will give the OP some information to analyse.

Simon

[Chris56000]

My Sat Nav directed me to a junction with the A1 in Lincolnshire (a dual carriageway junction so it counts), and then asked me to turn right across a busy live carriageway. After waiting a few minutes for a gap, I gave up, turned around and went another way. As all-movement T junctions go, it was very dangerous. There are some perfectly good ones on less busy dual carriageways where the junction includes splitter islands and a wider central reservation to facilitate a two-stage right turn.

I simply wouldn't attempt to turn right onto any busy dual–carrigeway at–grade unless the central reservation gap is wide enough to contain the entire length of the car, and then only if the road is virtually clear of traffic – it's far safer to turn left or find another route to a roundabout junction or GSJ with the d/c road along the minor routes than risk a potentially fatal high–speed collision with what could well be, in today's traffic, a HGV rather than another car!

I completed the Questionnaire!

Chris Williams

[jackal]

4-level stacks look like utopia for conflicts, but are extremely expensive, have considerable land take

While that's the traditional view, the design for Lofthouse is not much bigger than the stackabout.

I also don't think £435,000,000 is all that expensive for what it is (the Wisley sticking plaster is about half that).

[J N Winkler]

I also felt like a lot of my answers were an arbitrary guess. How am I supposed to sensibly rate a junction for safety or peak time traffic flow if it doesn’t exist in the UK and I’m only allowed to answer from my own experience?

I have about 30 years of experience driving in the USA, Canada, the UK, Ireland, and Mexico, and have encountered at least one instance of all the junction types asked about with the sole exception of the double crossover merging interchange (TRID blurb). I do not know of a single built example anywhere.

The one example of a continuous-flow intersection I have driven through (in 2001-02 and 2002-03) was in Chihuahua and does not exist anymore, having been replaced with a grade separation. (Utah DOT has gone for CFIs on SR 154/Bangerter Highway in a big way, but I haven't seen those in person.)

The diagram of a turbine interchange was interesting: it showed two exits per carriageway, but entry slips combined to make one merge per through carriageway. That variant doesn’t exist anywhere in the UK. I also found the diagrams of a crossroads and a T junction bewildering!

It might be interesting to use the OpenStreetMap illustrations as the basis of a WAI.

I got to the end of the survey and submitted it, but it is very subjective depending on whether the examples you think of are good or poor. However, it is about public perception rather than objective research into junction types so I guess it will give the OP some information to analyse.

I confess to some skepticism even about that. Engineering practice might be more geographically even in the UK to the extent that this issue doesn't arise, but in the US we now have the phenomenon of the "roundabout mecca" (examples: Carmel, Indiana, and Malta, New York), often blamed on design policies that require specific justification for flat intersection types other than a roundabout. How do you separate out frustrated residents of Carmel and Malta from the mass of responses?

[Vierwielen]

I started doing the questionaire and then found myself asking the question "Do I include my foreign travel?" - after all I have spent about three years working in various Continental countries (1999-2001 & 2012) and also I learnt to drive in South Africa and had a full South Africa driving licence for the last five years that I spent there.

Other Sabristi have commented on the single clover-leaf junction in the UK (which I have never used), but I have used many clover leaf junctions in Germany and Italy. I really need instructions on how to answer your questions.

Another comment that I have is that different types of junctions are suited to different levels of traffic flow. Your questions do not appear to take this into account.

[c2R]

I confess to some skepticism even about that. Engineering practice might be more geographically even in the UK to the extent that this issue doesn't arise, but in the US we now have the phenomenon of the "roundabout mecca" (examples: Carmel, Indiana, and Malta, New York), often blamed on design policies that require specific justification for flat intersection types other than a roundabout. How do you separate out frustrated residents of Carmel and Malta from the mass of responses?

If I was starting from scratch, I'm not sure I'd sign how to use a roundabout like that: https://www.google.com/maps/@42.9705817 ... 384!8i8192

and then differently at the next one! https://www.google.com/maps/@42.97103,- ... 384!8i8192

[Rob590]

I ploughed through and completed this but as others have said - best of luck with your dissertation, but this is a fairly poorly designed questionnaire and (as someone who teaches questionnaire design at university) I'd encourage you to consider re-designing it, if you've not yet rolled it out much.

I'm uncertain what your research questions are but if your question is about public perception of junction types, I'd strongly recommend reducing your options to maybe 5 very common types that people have encountered, and 2 hypotheticals. Your survey is looooong, and asks a lot from participants. People will give up on it. There's not much point asking people about their experience of uncommon junction types because you'll get such a small sample of people who've actually encountered them that you won't get much meaningful data.

If you can't use software that gives people a progress bar ("question 5 of 30" or something similar), give an estimated time at the start of the questionnaire -"this survey should take 15 minutes to complete" or something similar.

On the final pages, reword so you're prompting people to pick one junction. Perhaps something like "What is your favourite junction to use" and then your "why" questions, followed by a "least favourite".

I'd agree with others that if people haven't encountered a junction type, the following questions don't really make a lot of sense.

You might consider specfying if you only want people to reflect on their experieneces in the UK

You could put "don't knows" for each option.

Good luck with everything!

[WHBM]

I simply wouldn't attempt to turn right onto any busy dual–carrigeway at–grade unless the central reservation gap is wide enough to contain the entire length of the car, and then only if the road is virtually clear of traffic – it's far safer to turn left or find another route to a roundabout junction or GSJ with the d/c road along the minor routes than risk a potentially fatal high–speed collision with what could well be, in today's traffic, a HGV rather than another car!

Try this one, exiting the M11 northbound at J5 , just by Debden Underground station, which is exactly that. To add to it, the central reservation has a concrete barrier and shrubbery right in the sightline of traffic approaching on the far carriageway. Quite how it's survived 40 years without signals I can't quite fathom. I'd love to see their risk assessment.

https://www.google.com/maps/@51.6407962 ... 384!8i8192