Civil Engineering Reference
In-Depth Information
Table 13.9
Annual (2002) estimated congestion costs (Million $$) in various Canadian cities
Location
Threshold
50 % 60 % 70 %
Vancouver $737 $927 $l,087
Edmonton $96 $116 $135
Calgary $185 $211 $222
Winnipeg $121 $169 $216
Hamilton $20 $33 $48
Hamilton (old) $17 $23 $30
Toronto $1,858 $2,474 $3,072
Ottawa-Gatineau $100 $172 $246
Ottawa-Gatineau (no rural) $97 $166 $238
Montreal $1,179 $1,390 $1,580
Qucbcc City $73 $104 $138
Total, base $4,370 $5,596 $6,745
Total, Old Ham./no rural Ottaiva-Gat. $4,364 $5,580 $6,721
Note
Congestion costs were estimated from a combination of sample observations (e.g.,
fl
floating
car method, traf
c counts), travel demand models and transportation supply models
Source
Reference [
23
], p 5.5-16, Table 5.5.4-3
Table 13.10
Estimates of congestion speeds for three threshold speeds in canadian cities
City 1
City 2
City 3
Free-
fl
ow speed (mph)
60
60
60
Threshold speed as % of free-
fl
ow speed (%)
50
60
70
Threshold speed (mph)
30
36
42
Actual speed (mph)
30
30
30
Congestion speed reduction (mph)
None
6
12
traf
c delays that produce crashes. Similarly, complex and offset street intersec-
tions, absence of turning lanes, unduly long traf
c signal cycles, and on-street
parking can create long queues during peak traf
c periods that are often the cause of
rear-end collisions.
Traf
c congestion increases the density of vehicles occupying the road (vehicles
per mile of road increases). As vehicles follow each other at close spacing, tend to
change lanes more frequently, and merge into crowded lanes to exit or enter the
roadway, the risk of crashes increases (Fig.
13.3
,[
2
]).
Research in Colorado [
25
,
26
] also found a relationship between traf
c volume/
density, speed, and crashes (Fig.
13.4
). This
gure shows how the crash rate
increases with both AADT and traf
c density (passenger cars per lane per mile): At
60,000 AADT, the crash rate is 0.64. At 96,000 AADT, it is 0.85., and at about
150,000 AADT, with a
density greater than 45 pc/mi/ln, the crash
rate is 1.56 crashes per million VMT. The authors conclude that better managed
Interstate freeways could lead to reduced crash rates.
“
super critical
”
