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Crossing conditions and kerb delay assessment
for better safety and accessibility of road
pedestrian crossings at urban intersections
Leonardi, S. a Tesoriere, G., b Distefano, N.,a Pulvirenti, G., a Canale, A., b
Campisi, T. b
a Department of Civil Engineering and Architecture, University of Catania, Via Santa Sofia
64, Catania, 95125, Italy
b University of Enna Kore, Faculty of Engineering and Architecture, Cittadella Universitaria,
Enna, 94100, Italy
The accessibility of urban contexts is closely connected to analysis of geometric
and functional details that can influence the actions of road vulnerable users. The
correct design of the spaces and their accessibility must consider all age groups
and problems related not only to safety but also to perception and comfortable
movement. This research investigated the behavior of 3887 pedestrians (both el-
derly and non-elderly people) in two pedestrian crossings located in an urban in-
tersection of Catania. Two video cameras were used to record oncoming vehicles
and pedestrians at the intersection. An initial analysis of the number of le-
gal/illegal crossings was developed in order to understand if different crosswalk
setback distances lead pedestrians to illegal crossings. The results show that pe-
destrians prefer to cross choosing the shortest way, even if this leads to illegal
crossing. Then, the kerb delay was calculated, i.e. the time interval between the
moment in which the rear part of the last vehicle in the queue exceeds the pedes-
trian waiting for crossing and the moment when the pedestrian takes the first step
to cross. The hypothesis that older pedestrians have longer kerb delay because of
declines in their physical, sensory, perceptual or cognitive abilities was tested.
Pedestrians are the most vulnerable road users’ category in traffic accidents,
especially in urban areas. Despite public, political and scientific efforts to reduce
the amount of pedestrian accidents in traffic all over the world, there are still a
considerable number of severely hurt or even killed pedestrians every year. The
World Health Organization  reported that more than 1.2 million people die eve-
ry year in traffic accidents worldwide, and that 22% of these casualties are pedes-
trians. Learning about pedestrians’ crossing decisions and movement prior to and
while crossing the road may portray pedestrians’ intentions and behaviours.
The reality of an aging population, particularly in ‘‘economically developed”
countries, has made the everyday mobility of seniors an issue of growing interest.
According to the United Nations’ World Population Ageing report , nearly eve-
ry country is experiencing growth in the elderly population that will create chal-
lenges and transformations in various socioeconomic domains. In transportation,
the ageing population poses mobility-related challenges in ensuring sufficient ac-
cess to facilities and services for the elderly. In order for walking to become an at-
tractive, efficient, and safe mode of transportation for the elderly, the way public
spaces are designed must be rethought/reconsidered in order to accommodate to
their needs and preferences. Urban structure plays a key role in providing availa-
ble paths  for pedestrian flows through urban areas. Improvement of accessibil-
ity between transit nodes and destination need to take into consideration urban fa-
cility designs. The correct design of the spaces and their accessibility must
consider all age groups and problems related not only to safety but also to percep-
tion and comfortable movement. The body of literature dealing with accessibility
of urban areas for vulnerable road users is extensive [4-7] The mobility of older
people in particular has been intensely investigated [8-10]. Various authors have
emphasized that to facilitate mobilities in later life, it is important that accessible,
clearly structured and predictable urban environments are provided , .
Crash statistics show that older people make up an extremely vulnerable road-user
group. There are several reasons for the higher proportion of fatality among older
pedestrians. Existing literature suggests that cognitive deficits , diminished
capabilities of human sensors ,  or changes in the crossing behaviours
,  could contribute to the increased crash rate for older pedestrians. Cross-
ing the street can be regarded as a challenging and demanding task because it re-
quires several processes, decisions, and actions to be performed quickly, some-
times in parallel. The act of crossing the street requires pedestrians to weigh up the
time saving against the probability of a collision. Older people are often thought to
precipitate their own accidents because of the way they cross the road. Their re-
duced physical capabilities result in less mobility and a reduced ability to move
out of the way of approaching cars. Furthermore, their traffic judgements may also
be quite different to those of younger people because of perceptual, sensory and
cognitive deficits. A number of human factors studies suggest that such factors
contribute to increased road behaviour risks [15-16-17]. Previous research has
shown that aging pedestrians have difficulty selecting safe gaps to cross the street
, . Older people have also been shown to have difficulty handling chal-
lenging traffic situations such as two-way streets. Whereas their street-crossing
safety is significantly greater on one-way streets, older pedestrians are more likely
to get hit by a car during the second half of the crossing, i.e., on the far side of the
This study set out to investigate the behaviour of both older and younger adult
pedestrians to establish whether the older group experience particular problems
when crossing the road. In particular, it aimed to highlight behavioural differences
between younger and older pedestrians, and to suggest countermeasures to reduce
the frequency and severity of older pedestrian crashes. Road crossing behaviour
was analysed from unobtrusive video recordings of road crossings for a sample of
younger and older pedestrians at one four-leg urban intersection. The study focus-
es on two crosswalks of the selected intersection, located respectively on a one-
way divided road and on a two-way divided road. An initial analysis of the num-
ber of legal/illegal crossings was developed in order to understand if different
crosswalk setback distances lead pedestrians to illegal crossings. Then, for the le-
gal crossings, the video footage was processed in order to calculate a parameter
named kerb delay, i.e. the time interval between the moment in which the rear part
of the last vehicle in the queue exceeds the pedestrian waiting for crossing and the
moment when the pedestrian takes the first step to cross. The hypothesis that older
pedestrians have longer kerb delay because of declines in their physical, sensory,
perceptual or cognitive abilities was tested.
2.1 Study locations
Observations were made in an urban four-leg at grade intersection (Fig. 1) lo-
cated in Sant’Agata Li Battiati, a small town in the Metropolitan Area of Catania.
Fig. 1. Plan view layout of study locations and observational filming.
The site was selected after screening of local streets via field observations. The
main street (Via Vincenzo Bellini) is a two-way undivided road with one lane on
each side. Each lane is 6 meters wide. The sidewalk on the main street is 3 meters
wide. There are two crosswalks on the main street. The secondary street (Via dello
Stadio) is a one-way undivided road with one lane (7.8 meters wide). The side-
walk on the secondary street is 1.3 meters wide. There is only one crosswalk on
the secondary street. This study focuses on a crosswalk located on the main street
and a crosswalk located on the secondary one. The crosswalks analysed have the
following features (Fig. 1): A) Crosswalk 1 is located on the secondary street, i.e.
one-way undivided road with one lane. It is 7.8 meters long and 4 meters wide.
The crosswalk setback distance is 6.50 meters. There are no bollards or other dis-
posals to avoid illegal crossings; B) Crosswalk 2 is located on the main street, i.e.
a two-way undivided road with one lane on each side. It is 12 meters long and 4.5
meters wide. The crosswalk setback distance is 3.50 meters. There are no bollards
or other disposals to avoid illegal crossings.
2.2 Video data collection and analysis
Two synchronized cameras were used to record the natural scene at the sites. A
car parked in front of Via dello Stadio on the side of the road was set up with two
video cameras positioned to provide images of both oncoming traffic and crossing
pedestrians. The cameras were hidden into the car so that pedestrians could not see
them. Filming occurred without pedestrian’s knowledge to overcome possible
changes in behaviour. Figure 1 shows a plan-view layout of observational filming.
Camera 1 was used to record pedestrians on crosswalk 1, while camera 2 was used
to record pedestrians on crosswalk 2. Video recordings of 1578 elderly pedestrians
(estimated to be ≥ 65 years) and 2309 non-elderly pedestrians (estimated to be <
65 years) were made for a total of 24 hours. The video recordings were made be-
tween 10:30 a.m. and 12:30 a.m. on weekdays for four days in September 2019,
eight days in January 2020, eight days in February 2020 and four days in June
2020. The hourly intervals of the video recordings were chosen so that the vehicle
flows and the approaching speeds were comparable on all four legs of the intersec-
tion. A random and concurrent selection of participants was used, that is, as they
entered the site without any selection bias. The video was played in Adobe Premi-
ere Pro CS4 version 4.0.1 to perform a frame by frame analysis.
2.3 Indicators to describe crossing behaviour
In order to analyse pedestrians crossing behaviour, two variables were consid-
ered: the crossing conditions (legal and illegal) and the kerb delay.
By the law, in Italy, on intersections controlled by STOP signs there has to be
a crosswalk setback distance of at least 5 meters. However, the crosswalk setback
results in a deviation from the linear path that pedestrians are led to follow sponta-
neously. People indeed naturally hope to reach their destinations quickly, so they
are not likely to make a detour. The two crosswalks studied were chosen purpose-
ly with different setback distances, in order to understand the availability of pedes-
trians to deviate from the linear path when there are no bollards or other disposals
which force them to cross on the crosswalk. When a pedestrian does not cross at
crosswalk, the crossing has to be considered illegal. The number of illegal/legal
crossings was calculated for all the crossing pedestrians observed.
The kerb delay was the time from when the back of the last vehicle passed a
waiting pedestrian to the first step forward onto the roadway . Figure 2 sche-
matically explain the kerb delay. The kerb delay was calculated only for the pe-
destrians who stopped before deciding to cross after a vehicle passed their line of
crossing. Most of pedestrians observed did not stop waiting for a vehicle to pass,
but, although slowing down, they continued walking in a “zigzag” among cars.
Only 426 pedestrians (198 elderly pedestrians and 228 non-elderly pedestrians)
crossed in a way which allowed to calculate the kerb delay.
Fig. 2. Schematic explanation of kerb delay.
3. Results and discussion
3.1 Analysis of crossings conditions
Table 1 shows the number of illegal/legal crossings for younger and older pe-
destrians for the two crosswalks analysed. Almost the totality (96.01%) of cross-
ings on crosswalk 1 are illegal. The percentage of non-elderly pedestrians crossing
illegally (97.38%) is slightly higher than the percentage of elderly pedestrians
crossing illegally (93.88%). Only 24.66% of crossings on crosswalk 2 are illegal.
The majority (75.34%) of crossings on crosswalk 2 is legal. The percentage of
non-elderly pedestrians crossing illegally (29.11%) is slightly higher than the per-
centage of elderly pedestrians crossing illegally (19.40%). These results clearly
show that pedestrians prefer to cross choosing the shortest way, even if this leads
to illegal crossing. The setback of crosswalk 1, which is more than 6 meters long,
leads indeed more than 95% of pedestrians to cross illegally and choose the short-
est path (that is as close as possible to the corner of the intersection). Conversely,
crosswalk 2 is regularly used by over 75% of pedestrians, as it is very close to the
corner of the intersection and, therefore, consistent with the need of minimizing
the length of the route.
Table 1 – Number of illegal/legal crossings for non-elderly and elderly pedestrians for crosswalk
1 and crosswalk 2.
Total (non-elderly + elderly)
Total (non-elderly + elderly)
As for the influence of the age, the results allow to conclude that there is no
clear difference between elderly and non-elderly users regarding the way they
cross on crosswalk 1. The percentage of non-elderly and elderly pedestrians cross-
ing illegally on crosswalk 1 are indeed similar (97.38% and 93.88% respectively).
Anyway, these results can be interpreted in a different way for younger and older
pedestrians: younger pedestrians probably cross illegally on crosswalk 1 because
they want to reach their destinations quickly; older pedestrians, instead, probably
choose to cross illegally because they choose the less tiring route (which is the
shortest one). On the other hand, there is a certain difference as for the number of
illegal crossings of non-elderly and elderly pedestrians on crosswalk 2. About
80% of elderly pedestrians cross legally on crosswalk 2, while a smaller percent-
age of non-elderly pedestrians (about 70%) cross legally. Although the setback is
small on crosswalk 2 (3.5 m), there is still a non-negligible percentage of non-
elderly pedestrians (29.11%) who choose the shortest and fastest route; the elder-
ly, on the other hand, show greater caution preferring to cross legally even if this
involves a slightly longer path.
3.2 Analysis of kerb delay
Table 2 shows the average kerb delay values for elderly and non-elderly pedes-
trians for crosswalk 1 and crosswalk 2.
Table 2 – Average kerb delay for non-elderly and elderly pedestrians for crosswalk 1 and cross-
Kerb delay (seconds)
Non-elderly pedestrian (< 65 years)
Elderly pedestrian (≥ 65 years)
The kerb delay allows to determine, respectively, the delay or the anticipation
of the pedestrian in crossing with respect to the incoming vehicle. The delay oc-
curs when, after the vehicle passes, leaving the space free for the pedestrian to
cross, the pedestrian hesitates to cross immediately. The advance occurs when the
pedestrian, from a static position, starts to cross before the incoming vehicle has
left the free space behind it to allow the pedestrian to cross.
From Table 2 it can be seen that older pedestrian delayed on both crosswalk 1
and 2 (+0.042 s and +0.517 s) before making their first step forward after the rear
of the last vehicle has passed them. By contrast, younger pedestrian commenced
the cross before the rear of the last vehicle has passed them on both crosswalk 1
and 2 (-0.784 s and -0.034 s). This is in line with the findings of Oxley et al. 
who also found that older pedestrians delayed before making their first step for-
ward after the rear of the last vehicle had passed them, while younger pedestrians
commenced the road cross immediately.
Older pedestrians took longer to make their first step forward after a vehicle
passed their line of crossing. It might be that older adults adopt an inefficient
crossing strategy in comparison with younger adults by waiting for the last vehicle
to pass before commencing the road cross. In older adults, increased kerb delay
may be the result of reduced reaction time, slower decision making capacity
and/or slower motor coordination, or simply greater prudence. On the other hand,
the negative values of the kerb delay for younger pedestrian are indicative of
greater reactivity and confirm the tendency of non-elderly pedestrian to cross
quickly and minimize time wasters that was already stressed in paragraph 4.1.
By comparing the kerb delay values obtained for the two crosswalks it can be
observed that the kerb delay values are higher for crosswalk 2 for both elderly and
non-elderly pedestrians. By contrast, pedestrians have more rapid reactions on
crosswalk 1. This shows that the kerb delay is also influenced by the complexity
of the crosswalk. Crosswalk 2, which is 12 meters long and located on a two-way
undivided road, leads indeed to greater delays, compared to crosswalk 1, which is
8 meters long and located on a one-way undivided road.
Pedestrian safety is related to the concept of accessibility and is assessed by taking
into account different aspects of both the functional geometry and the pedestrian's
Specifically, the delay of the sidewalk by a certain type of user is influenced by
the complexity of the adjacent pedestrian crossing and by what surrounds it (i.e.
traffic flow, signs, traffic lights...).
The present work lays the basis for future research on the correlation between
pedestrian safety and city accessibility, paying particular attention to the crossing
areas. The results obtained allow to define specific actions to be taken in the ana-
lysed area and therefore support the choices of future planning and/or mitigation
of current critical issues by the Local Administration. In addition, a more in-depth
and protracted analysis over a longer period of time on infrastructure geometries
and illegal crossing actions will make it possible to define and calibrate some syn-
thetic safety parameters that may include the assessment of pedestrian safety near
an intersection but also the comfort of the portion of the road (crossing) and
pavement dedicated to the weak user of the road.
The aim of these assessments is therefore a general increase in the safety of ur-
ban and suburban mobility for residents and tourists, particularly in areas where
there is a high level of pedestrian transit, through safer solutions for pedestrian
Therefore, future research steps will include an analysis of the current safety sit-
uation of existing pedestrian crossings, with the identification of the most critical
areas (e.g. near schools, hospitals, etc.), in order to guarantee everyone, especially
the most vulnerable such as children, elderly and disabled people, the right to walk
safely and independently in their city.
 World Health Organization, “Global Status Report on Road Safety,” World Heal. Organ.,
p. 20, 2018.
 United Nations, World Population Ageing 2017 - Highlights (ST/ESA/SER.A/397). 2017.
 C. T. Voulgaris, A. Loukaitou-Sideris, and B. D. Taylor, “Planning for pedestrian flows in
rail rapid transit stations: Lessons from the state of current knowledge and practice,” J.
Public Transp., 2015. https://doi.org/10.5038/2375-0901.18.3.1
 S. Canale, N. Distefano, and S. Leonardi, “Comparative analysis of pedestrian accidents
risk at unsignalized intersections,” Balt. J. Road Bridg. Eng., 2015.
 N. Distefano, S. Leonardi, and G. Pulvirenti, “Home-school travel: Analysis of factors af-
fecting italian parents’ mode choice,” Civ. Eng. Archit., vol. 7, no. 3, pp. 75–87, May
 S. Leonardi, N. Distefano, and G. Pulvirenti, “Italians’ public opinion on road rounda-
bouts: A web based survey.,” in Transportation Research Procedia, 2020.
 I. Mrak, T. Campisi, G. Tesoriere, A. Canale, and M. Cindrić, “The role of urban and so-
cial factors in the accessibility of urban areas for people with motor and visual disabili-
ties,” AIP Conf. Proc., vol. 2186, no. December, 2019. https://doi.org/10.1063/1.5138076
 B. Van Hoven and L. Meijering, “Mundane mobilities in later life - Exploring experiences
of everyday trip- making by older adults in a Dutch urban neighbourhood,” Res. Transp.
Bus. Manag., vol. 30, no. August, p. 100375, 2019.
 P. Jittrapirom, W. Van Neerven, K. Martens, D. Trampe, and H. Meurs, “The Dutch elder-
ly’s preferences toward a smart demand-responsive transport service,” Res. Transp. Bus.
Manag., vol. 30, no. April, p. 100383, 2019. https://doi.org/10.1016/j.rtbm.2019.100383
 G. Pulvirenti, N. Distefano, and S. Leonardi, “Elderly perception of critical issues of pe-
destrian paths,” Civ. Eng. Archit., 2020. https://doi.org/10.13189/cea.2020.080104
 R. Risser, G. Haindl, and A. Sta, “Barriers to senior citizens’ outdoor mobility in Europe,”
Eur. J. Ageing, pp. 69–80, 2010. https://doi.org/10.13189/cea.2020.080104
 J. Oxley, E. Ihsen, B. Fildes, and J. Charlton, “Age-related functional impairments and the
impact on the ability to cross roads safely,” Traffic Saf., 2001.
 R. Lobjois and V. Cavallo, “The effects of aging on street-crossing behavior: From estima-
tion to actual crossing,” Accid. Anal. Prev., 2009.
 J. Oxley, B. Fildes, E. Ihsen, J. Charlton, and R. Day, “Differences in traffic judgements
between young and old adult pedestrians 1,” Accid. Anal. Prev., vol. 29, no. 6, pp. 839–
847, 1997. https://doi.org/10.1016/S0001-4575(97)00053-5
 G. E. Stelmach and A. Nahom, “Cognitive-motor abilities of the elderly driver,” Human
Factors. 1992. https://doi.org/10.1177/001872089203400107
 T.Campisi ,G. Tesoriere, & A. Canale. “The pedestrian micro-simulation applied to the
river Neretva: The case study of the Mostar “old bridge”. In AIP Conference Proceed-
ings (Vol. 2040, No. 1, p. 140004). AIP Publishing LLC.2018.
 G.Tesoriere, A.Canale.,A. Severino, I. Mrak.& Campisi, T. (2019, December). The man-
agement of pedestrian emergency through dynamic assignment: Some consideration about
the “Refugee Hellenism” Square of Kalamaria (Greece). In AIP Conference Proceed-
ings (Vol. 2186, No. 1, p. 160004). AIP Publishing LLC.