Transport Engineering 4 Topic 3: Junction Sequencing


TE4: Topic 3 Notes:
Signalised Junction Sequencing
1.0 Introduction
“What’s the difference between a highway engineer and a traffic engineer? A highway engineer
designs roads for traffic and a traffic engineer designs traffic for roads.” Highway engineers deal with
space and their currency is millimetres, whereas traffic engineers deal with time and their currency
is seconds. In the other half of Topic 3 we were Highway Engineers making sure our junction was
well spaced out so people walking, cycling, and also driving could all use the junction safely without
avoidable conflict. Now we become Traffic Engineers, where we set all the different movements at
junctions to appropriate timing.

2.0 Signals and Lost Time
In this course we will use standard UK traffic light cycles, the difference in other countries is usually
how they treat the amber phase1. One full cycle of the traffic lights is Red (Stop), Red/Amber (Stop,
but get ready for the green), green (go), amber (stop unless it would be dangerous to do so).


In UK law Red/Amber and Amber are fixed at two and three seconds respectively. So that leaves the
Red and Green signals as the ones where we, as Traffic Engineers, can use to make our junction work
as best as it can.
Traffic Engineering is particularly specific about terms, and which terms should be used when. The
first term we will learn is a cycle. A cycle at a junction is effectively how long it takes everyone to
have a go. In the UK this will typically be between 80 and 120 seconds. Although many junctions will
have sensors which can significantly shorted this cycle length at times of lower traffic flow2.
Lost time is our next term when no vehicles are moving. What is interesting is that cycles (bikes) are
vehicles but pedestrians are not. Now perhaps we realise why pedestrian signals always feel rushed

1 There’s a Vienna Convention which standardised the colour of traffic lights in all countries to red and green.
However many green lights in Japan can be quite blue due to the Japanese language traditionally not
differentiating between green and blue.
2 Alas many Glasgow junctions seem to be missing this feature, which means that if you are walking and
waiting for your green man you could be waiting a while despite streets empty of traffic.
Transport Engineering 4 Topic 3: Junction Sequencing


as when walking we do not count towards the metric of an efficient junction3. The good news is that
Lost Time is easy to calculate, simply sum up the intergreen times (including pedestrian only stages)
and minus one second.
Intergreen times are the amount of time between one arm of a junction losing its green light to the
next arm of a junction gaining a green light. We can’t just immediately switch between greens, as we
would find excited drivers would plough into the side of the cars of those who haven’t yet exited the
junction from the previous green. In UK guidance, the intergreen time required depends on the
distance from the stop line that has received a red signal, to a point perpendicular to the arm
receiving the green signal4. If this distance is less than 9m, then the intergreen is 5 seconds. If it is
10-18 metres, then it is 6 seconds, and if it is 19-27m, then it is 7 seconds.
But what difference does a second make? Well, if we have a junction that allows 10,000 vehicles
through a day and each of those is delayed by one second ....... then this adds up to 3hrs total delay.
Our Transport Planning colleagues might wish to put a monetary value on that and tell us to solve it.
So seconds really count.

3.0 Movements, Phases, and Stages
Now we turn our attention to Movements, Phases, and Stages. These are important concepts that
are easy to mix-up, however they are vital terms for Traffic Engineering so make sure you fully
understand them as it will be easy to get all mixed up in your group assignment. We will ignore
people walking and cycling for now to focus on vehicular traffic to understand these concepts.
First off let’s deal with movements
for vehicular traffic by using the
signalised junction between Byres
Road and University Avenue as an
example. Each of the streets
leading to the junction is often
referred to as an arm, so the
junction on the left has four arms.
For each arm sketch out the
possible movements that vehicles
will regularly take. For this
junction, the vehicles can carry
straight on, turn left, or turn right5.
Our next step is to group these movements into phases, we give each phase an assigned letter6.
Phases are those movements which would ALWAYS occur together. Below, for each arm, you can
see I’ve group the straight on and left turn together but kept the right separate. That’s because
there’s no situation here where straight on would be separated from left turn at an arm, but I can
think of situation where the right turn might be separate.


3 Perhaps quite telling that for many engineers signalised junctions are primarily about maintaining traffic flow
rather than thinking about safety of those not in cars.
4 Which is the junction in Glasgow which release one arm at a time go round anti-clockwise.
5 If you look at the signalised junctions at the top and bottom of Byres Road then you’ll notice some right turns
are banned.
6 That’s just how it is done.
Transport Engineering 4 Topic 3: Junction Sequencing




Our next step is to group the non-conflicting phases into stages, we give each stage an assigned
number7. In the UK we are actually allowed to have conflicting right turns group into stages, I will
show how that works later. Below you can see the actual stages of the real junction. Each arm is
released in turn and drivers can turn left, right, or carry straight on with no conflict. After each arm
gets its turn Stage 5 is the pedestrian stage. In the UK we are not allowed to have pedestrian stages
where vehicular traffic turns across (and gives way) to the pedestrians8.



Some of you might start connecting the dots and noticed that 5 stages is quite a lot and that
between each stage will be an intergreen period which delays all people hoping to get through the
junction. Perhaps if we could reduce the number of stages we could have a more efficient junction?



7 That is also just how it is done.
8 Common practice in every other European country I think, but there we go.
Transport Engineering 4 Topic 3: Junction Sequencing


This is another possible Stage
sequence for the Byres Road
Junction. For Stage 1 and 2 the
straight on and left turns are
not in conflict so fine to occur
concurrently. The people
wanting to turn right will have to wait till the junction has cleared and then make their turn.
Fortunately this junction is large enough to have right turning vehicles not blocking vehicles going
straight on. However, we will need longer green times to make sure the junction clears to allow right
turns, perhaps at rush hour this green is so long that we actually get reduced throughput?
We could do something called
an early cut off, as shown to
the right. Where we put our
straight on and left turns on a
red light, and let our right
turners have a go. The
disadvantage for the Byres
Road junction in our first 5
stage option (each arm at a
time) then straight on could
use the left or right lanes. Now
straight on could only use the
left lane, so we might find that
once again throughput is actually less that our first option9. There’s also the disadvantage that
waiting to turn right, or having vehicles turning right in front of you, is pretty uncomfortable
for people cycling at junctions like this.
You might be asking how the Dutch Junctions are phased and staged in the Netherlands? Well, the
Netherlands are allowed concurrent pedestrian and cycle phases with priority over turning vehicles,
each of 20s. That means there is steady throughput of the junction. But the analysis we do in the UK
means that it would probably show up as
less efficient overall. We might still need
early cut off for the right turns. Also, it’s
completely unlawful in the UK to do this,
so rather than concentrate our efforts on
changing rules in central government we
can think how we could improve things in
the constraints that we have.









9 I imagine that this is very likely with this junction. Someone at Glasgow City Council has probably done all this
analysis to come up with the present solution.
Transport Engineering 4 Topic 3: Junction Sequencing


The image to the right includes
a possible solution to make
this a better junction for
pedestrians. Why not have two
pedestrian stages per cycle?
Sure this would cut down the
amount of vehicular traffic
throughput, but it wouldn’t
affect those cycling so much as
they could filter to the front.
The reason that Glasgow City
Council wouldn’t let you do
this, is that this would show up
on their models as slowing down buses at peak times. Perhaps it could be done at off-peak times
only when you have lots of people out enjoying the bars, cafes, restaurants, and shops on Byres
Road?
I hope that this section has shown the importance of the Traffic Engineering side to signalled
junction design. For a relatively simple junction we have talked through five distinct options for
arranging phases and stages at a relatively simple junction. But finally one last term, each of these
five arranged stages is known as the method of control.

4.0 Pedestrian and Cycling Timings
So how long do people walking and cycling get at junctions? For people walking we take the distance
of the crossing and use different walking speeds to work out a suitable time. We don’t want people
to be rushed, so a typical traffic engineering approach has been to use the 85th% slowest walking
speed and use that, which is usually between 1.0-1.2 m/s10. However, consider if you were one of
those 15% slower people, perhaps due to some sort of mobility impairment. At every single crossing
then you cannot get across in time, any walk along streets would feel like a rushed non-relaxing
experience. But yet the Traffic Engineering metrics push us to reduce pedestrian times to as little as
possible, remember the lost time issue?
Especially in projects to enable active travel, consider how you can make signalled junctions better
for those walking. One option is traffic engineering related to increase pedestrian green time, but
let’s not forget our street engineering perspective and consider if we can make the pedestrian
crossing distance shorter11.
But what about cycling? Well at Dutch Junctions and CYCLOPS we probably want at least enough
time for people cycling to be able to make a right turn. You might start worrying about complex
things like distribution of cycling speeds across a population, acceleration, cornering speeds, how
other junction factors would affect speed of cycling ........... but actually, since on both Dutch Junctions
and CYCLOPS in the UK we have combined pedestrian and cycling stages .... then fortunately the
pedestrian timings are almost always sufficient to achieve our goals for people cycling around the
junction. Phew!



10 I currently setting up research projects which collects data on people’s walking speeds in built up areas. Its
something that we are really lacking.
11 This is one of the advantages of the CYCLOPS.
Transport Engineering 4 Topic 3: Junction Sequencing


5.0 Headway, Saturation, and Capacity
This section details some final concepts and definitions that are useful to have when discussing the
Traffic Engineering aspects of signalised junctions.
Headway is the distance between the front of one vehicle and the front of the one following. In
general, the smaller the headway then the higher the capacity. Somewhat counterintuitively,
increasing speeds actually leads to lower overall capacity due to an increase in headway. This is why
particularly busy sections of motorway might have lower speed limits which might feel silly to an
individual driver as reduces their speed but actually allows far more vehicles to flow at peak times.
Headway might be the distance between vehicles, but its measured in time…….the time for a vehicle
to move the headway distance.
Saturation flow is the maximum flow through a junction when it is performing at its best. When a
traffic signal goes to red and amber, drivers have to wake up and react. People cycling then to react
more quickly and so clear through junctions much quicker than drivers, who have to engage engines,
drop the hand brake, stop adjusting the radio or playing on their phone and move off. This reaction
time is lost time. They must then start moving and get up to speed. At some point, the arm in
question will flow at its maximum smooth throughput, and this is the saturation flow. This is a key
measurement for junction analysis, and varies for every junction, depending on layout, context and
conditions. Once the amber signal comes up, drivers must react again and slow down or stop12.
Capacity is the measure of the maximum discharge over a stop line in a given time. It is the
saturation flow expressed as a ratio of the allocated green time to the total cycle time. Obviously,
one arm is not always running, and capacity just corrects for this reality to give you a workable value.
One of the key junction performance indicators worldwide is the RFC value: the Ratio of Flow to
Capacity; also known as the degree of saturation. It is a ratio of the actual flow to the maximum
potential flow or capacity. Any walking and cycling project that adversely affects this figure usually
gets dropped or radically changed. If a civic authority asks for this figure, then the movement of
traffic is paramount to their concerns. This is the great unwritten law of signal control: thou shalt not
affect capacity. If demand flow or actual flow exceeds capacity, then this is the definition of gridlock.
It is a simple supply and demand problem. The magical value for this ratio is 85%, as this means that
there is enough capacity to cope with the flow and some slack is given to reaction time. This is the
hallmark of an efficient junction. This is the bottom line figure. So how do we calculate that?

6.0 Critical Movement Analysis
There are various sophisticated methods for analysing capacities of junctions depending on their
layout and Method of Control. In this class, we will use a straight-forward simplified method which
should be viewed as a generally accurate but “back of the envelope” style calculation. We do this
because in almost all situations you will find software does the job for you, by keeping things simple
my aim is that you will be able to focus on key decisions, judgements, and factors while doing your
junction design. I think this will put you in a better place to understand how to use the software in
industry to ask the right questions of your junction designs.
The method we use is called Critical Movement Analysis13. One of the key principles of Critical
Movement Analysis is that vehicles will generally flow with a headway of two seconds. That means

12 Or potentially try to race through knowing they have 2 seconds until it is illegal
13 This link will take you to a PDF Download of the document outlining the method in more detail.
http://onlinepubs.trb.org/onlinepubs/trnews/rpo/rpo.trn129.pdf
Transport Engineering 4 Topic 3: Junction Sequencing


that an un-interrupted traffic lane will have a capacity of 1800 vehicles per hour14. In signalised
junctions we have lost time, where we must switch between arms having green, Critical Movement
Analysis simply deals with this by assuming a “point capacity per lane” of 1400 vehicles per hour.
Remember that lost time is highly dependent on your Method of Control, how many stages for
example, but we find this ~20% assumption lets us get on with the job for this class.
The Critical Movement Analysis allows you quickly to:
• Estimate the traffic capacity of your junction.
• Evaluate your approach geometry (number of lanes going into a junction arm)
• Develop initial Methods of Control
• Understand what to expect from later software calculations (i.e., if your software is way
off your Critical Movement Analysis then perhaps one of your software inputs was wrong
or vice versa)
• Perform efficient and readily understandable options appraisal for your junction layout and
Method of Control.
Steps of Critical Movement Analysis
1. Identify movement and hourly volumes per lane: Review the approach geometry (number of
lanes) for each intersection arm. Obtain the traffic volumes in vehicles per hour, which are
then converted depending on how many lanes each arm has.
2. Assign movements to phases and stages: Fortunately, you’ll have done this as your Method
of Control anyway.
3. Determine critical volume pair in each interval: For conflicting movement pairs in each stage,
you need to calculate the sum of volumes on a per-lane basis. The highest movement pair is
identified at the critical volume pair15.
4. Sum critical volumes for each stage: For all stages, sum the critical volumes over the entire
cycle.
5. Identify maximum critical volume: This is the 1400 vehicles per hour as discussed earlier. But
if you have reason to use higher or lower volumes (and can justify it) then feel free to do so
6. Calculation Critical v/c ratio and determine junction status: This is done by dividing the sum
of critical volumes from step 4 by the maximum critical volume from step 5.

Use the table below to understand the implications of your junction layout and Method of
Control.

v/c ratio Assessment Implication
<0.85 Under capacity Expect little delay and minimal queuing
0.85-0.95 Near capacity May expect delays, but no excessive queuing
0.95-1.0 At capacity High delays expected and some queues won’t clear
until after peak traffic periods
>1.0 Over capacity High delays and excessive queuing expected

14 Notice how we’re now really into Traffic Engineering where we talk about vehicles rather than human
beings. The average number of people inside a car during rush-hour is 1.1.
15 I bet that sounds confusing, but it’s actually quite straightforward once you run through a few of the
examples in the workshop.
Transport Engineering 4 Topic 3: Junction Sequencing


Critical Movement Analysis Example
A four arm junction has the lane geometry and hourly traffic volumes shown in the following figure
and table. Note, to make things simple we are ignoring cycles on the road. Note that we are in a
right hand drive country


Approach Left Straight-on Right
EB 130 585 275
NB 95 370 64
WB 200 400 96
SB 185 400 130

Step 1: Geometry and traffic volumes are given, but you can count these for your chosen junction.
Step 2: It is assumed that the intersection first processes East-West traffic, followed by North-South.
Each left turn conflicts with the opposing straight on and right turn.
Step 3: Determine critical volume for east-west street.
EB LT + WB SO/RT = 130 + 0.516 x (400 + 96) = 378 vehicles per
hour. WB LT + EB SO/RT = 200 + 0.5 x (585 + 275) = 630 veh/hr
Therefor WB is critical as there are more vehicles conflicting in those movements.
Now let’s look at critical volume for north-south street
NB LT + SB SO/RT = 95 + 0.5 x (370 + 64) = 312 veh/hr
SB LT + NB TH/RT = 185 + 0.5 x (400 + 130) = 450 veh/hr (Critical)
Step 4: Sum critical volumes (630 + 450) = 1080 veh/hr

16 This is multiplied by 0.5 because there are two lanes that WB movement takes place. Note that drivers don’t
actually behave so well in real life and the middle lane might be more crowded with cars going straight on.
Hence this method is overestimating real life through put.
Transport Engineering 4 Topic 3: Junction Sequencing


Step 5: Assume maximum critical volume of 1400 veh/hr
Step 6: Estimate v/c ratio. 1080/1400 = 0.77.
Therefore, the intersection is currently under capacity.
We could use such an analysis to test out the effect of changing the Method of Control, or reducing
number of vehicle lanes. If we are going to reduce total traffic volumes in our cities, then a transition
stage might be to accept our junctions would be at over capacity until traffic decreases. Which
would require a significant amount of contingency and other planning.
Critical Movement Analysis from Glasgow
Let’s now look at an example from Glasgow of a junction similar to what you might choose for your
coursework. This is the junction between Gibson Street and University Avenue. Both the top left and
top-right streets are one way so we only have traffic entering the junction from the bottom-right
and bottom-left arms. I will call these BR and BL respectively.

Step 1: First I analyse the lanes to work out what movements that drivers are doing from each lane.
BL is easy because drivers do all three movements from one lane. For BR, then the left lane is for left
turn only and the right lane for straight-on and right turn.
Step 2: Great, now it’s time to work out the method of control. I did this by sampling visiting the
junction and watching the lights. See below for the method of control, we only have 3 stages at this
junction. Note that phase a exists in both stages 1 and 2. That is something that wasn’t covered in
the previous textbook example. I’ll have to have a think about how best to account for that.
Transport Engineering 4 Topic 3: Junction Sequencing





Then I did five 15 minute movement counts at the junction. Here are my averaged results (cyclists
are in brackets).

Approach Left Turn Straight On Right Turn
BR 137 (21) 62 (2) 18 (8)
BL 0 (1) 33 (37) 115 (22)

Note that the wider road layout leads to no left turns for BL even though this is permitted.
Step 3: Ok now it’s time to work out the critical volume for each stage.
Stage 1: Straight-on and right turn are in one lane (phase b) so we need to add them together to get
(62 + 18) = 80. But phase a continues to stage 2. I will assume that 2/3 of phase a occurs in stage 1
and 1/3 occurs in stage 2 (yes I probably should have just counted it properly when I was there). So
that gives us (137 *2/ 3) = 91. 91 is our critical volume for stage 1.
Stage 2: All three movements of phase c run from the same lane so we sum them (0 + 33 + 115) =
148. We also have 1/3 of phase a which is 46. So we know that 148 is our critical phase for stage 2.
Stage 3: Pedestrian stages are accommodated in our inter-green factor where we reduce our point
capacity per lane from 1800 veh/hr to 1400.
But have we missed something? Well, since there are no cycle facilities then we include people
cycling in our vehicle counts. Let’s err on the side of caution and assume 1 cyclist need the same
space at a junction as 1 car. In real life a cyclist needs considerably less space.
Stage 1: (62 + 2+ 18 + 8) = 90 and (137 + 21) * 2/3 = 105
Stage 2: (0 + 1 + 33 + 37 + 115 +22) = 208 and (137 + 21) * 1/3) = 53
Step 4: Sum our critical volumes (105 + 208) = 312 veh/hr
Step 5: Assume maximum critical volume of 1400 veh/hr
Step 6: Estimate v/c ratio. 312/1400 = 0.22.
Therefore our junction is under-capacity. Which is great? Not really, our junction is way under
capacity. But I took my counting in the daytime, perhaps I should revisit at peak vehicles times to
see the difference.
But what I could suggest based on these results, is that we could have two pedestrian stages in our
method of control at non-peak times. This would help students cross during lecture change overs.
But by doing this simple critical movement analysis, we can already start understanding our junction
Transport Engineering 4 Topic 3: Junction Sequencing


better, to better inform our subsequent redesign. Perhaps I can use this as justification for getting
rid of the BR left turn lane in order to fit in lots of space for cycling? I can adjust the numbers in step
3 to see what affect this would have on the v/c ratio.

7.0 Pedestrian Comfort at Signalised Junctions
Note: I didn’t get the spreadsheet from TfL required for this analysis in detail. So in your coursework,
you can skip straight to the final image and compare with your observations at the junction, to make
a judgement about whether your junction is currently more or less comfortable for pedestrians.
Now we are going to learn how to assess if our junctions are doing its job for people walking. The
last section for traffic, could be described as quite mechanical as in there is a clear process and we
have numbers which describe most elements and factors. However, when people walk, they
behave quite differently to when driving. When walking we will all bunch up together to wait,
sometimes we’ll be with friends so happy to pack in, other times out of politeness we might give
extra space to other people. When people walking are released by the green signal at junctions you
might notice that they scatter in all directions and speeds. So quite different to our three clear
movements for people driving at each junction arm. The other difference is that we can quite
happily let all pedestrians go at once, they are not going to cause accidents and will just manage
any interaction quite happily between them17.
Helpfully, Transport for London has created the Pedestrian Comfort Guidance18 which we will use in
this course to assess if our signalised junctions are working for those walking. As an engineer, this
method will provide you with the information and evidence to make a case for improving pedestrian
stages at signalised junctions. The Pedestrian Comfort Guidance seeks to inform three key questions.
• Is it comfortable to cross from one footway to another (or to the road island) in the space
provided by the crossing arm?
• If the crossing has an island, is it comfortable to walk from one arm of the crossing to the
other?
• How many rows of people will form when waiting to cross from the island to the footway?
Note that the research undertaken to develop the Pedestrian Comfort Guidance was for pelican
crossings. However, I think the guidance and learning are very applicable to our signalled junction
situations. A range of factors influence road crossing behaviour on signal controlled crossings and
the assessment does not consider other important factors such as whether the crossing is aligned
with pedestrian desire lines, or the impact of people waiting to cross on the clear footway width.
Step 1 Observations
Visit the site and make general observations. These following questions will help add a lot of useful
information to your design brief:
• Are there signs that the site is a route to and from school?
• Do people cross away from the formal crossing facilities?
• Does the size of the queue waiting to cross significantly interfere with people walking along
the footway?

17 Indeed, creating situations which create more positive opportunities for people to interact when walking is
usually a good thing, whereas for people driving we don’t really want that on distributer roads.
18 Technically its name is “Pedestrian Comfort Guidance for London” but it turns out London people are the
same as pretty much anywhere else so we can happily just take their methods for other locations.
Transport Engineering 4 Topic 3: Junction Sequencing


Step 2 Data Collection
For each of the junction arms collect the following data:
• The total demand for crossing the road. This includes people crossing during the green man,
blackout and red man pedestrian phases.
o Taking this information over 15 minutes is useful, then can multiply by 4 to get an
hour
o Collect at different times of day to get an idea of variability.
o Select an imaginary line some distance from each crossing arm, assume that
everyone who crosses within this area is part of the demand for crossing at the
junction.
• The signal timings for the pedestrian phases of crossings (green man, blackout and red man)
in seconds. If the crossing has a variable cycle length a number of cycles should be recorded
and the median taken.
• Measurements of the crossing arms and island, if present, in metres.
• If people are crossing diagonally, note if the presence of guardrail means that they have to
interact with those crossing just one junction arm.
Step 3 Data Input
On Moodle you will find a spreadsheet which helps you calculate key factors relating to pedestrians
comfort at your crossing arms.
• For each location enter the activity data for the site:
o Location name /Arm.
o Average Flow - average of all the samples taken throughout the survey hours.
o Peak Flow- average of the samples recorded in the peak hour or a reasonable
estimate at peak flow based on your data collection
• Input Measurement & Signal Time Data
o Measurements for each arm should be taken on site or from a suitable record such
as a topographic survey in metres, and entered into the spreadsheet (columns G to
H).
o Record the green man, red man and blackout time in seconds in column I to K. The
total signal time will then be calculated from these numbers.
• The spreadsheet will then automatically calculate the following:
o % time available to cross - This is the proportion of time in a signal cycle that people
can cross the road (during the green man and blackout periods).
o Relative People Per Hour (rpph) - This figure is calculated to use in the assessments,
as the people per hour (pph) figure used on footways assumes that movement along
the street is distributed evenly, i.e. 60pph means that 1 person will pass a point each
minute. On crossings this is not the case as people should only cross during the
pedestrian crossing phases. To reflect this the “relative pph” is calculated by dividing
the pph by the % of time available to cross. Therefore a pph of 60 where people can
cross the road 20% of the time is equivalent to 300pph.
o Crowding on the crossing arm - Pedestrian crowding is measured in people per
metre minute of the width of the crossing arm (ppmm) and is calculated using the
following formula: relative people per hour ÷ 60 ÷ crossing arm width in m
o Pedestrian Comfort Level Categorisation - The crowding level (ppmm) is then
categorised according to the Pedestrian Comfort Level scale.
Transport Engineering 4 Topic 3: Junction Sequencing


o Then, based on the demand for crossing the road and the number of cycles per
hour, it works out the average people waiting to cross per cycle. This is the average
size of the queue.
o Finally the number of rows that are likely to form is calculated by dividing the
average size of queue by the number of people in a row.
Step 4 Review and Interpret Results
The spreadsheet presents results in a few sections:
• Summary Information:
o This section summarises the key information about each arm of the crossing.
• Results for each assessment
o The spreadsheet then highlights the Pedestrian Comfort Level (PCL) for each arm
with data you have used.
o As with all things in Transport Engineering, this informs your design decisions for the
junction but does not dictate them.
o However, if the spreadsheet suggests and/or your own observations suggest a
poor level of pedestrian comfort, then in this class you are expected to try and
improve things.
The image below is from the pedestrian comfort guidance, and gives you a visual idea of what the
different comfort levels mean on the ground. Of course you might be will to allow your junction to
have brief periods in the day of discomfort for pedestrians, if it means not over designing your
crossing for most of the time.
Transport Engineering 4 alistair.mccay@glasgow.ac.uk Topic 3: Junction Sequencing