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methodologies incorporate the effects of intersections on av- 3. Lane additions leading up to or lane drops leading away
erage pedestrian and bicycle speeds, but do not consider from intersections;
other potential factors (such as interference). 4. The effects of grades between intersections;
Safety and Economic Factors: Safety and economic factors 5. Any capacity constraints between intersections (such as a
are not included in any of the LOS methodologies. narrow bridge);
Comparable Modal LOS: The HCM uses the same service 6. Mid-block medians and two-way left-turn lanes;
measure, speed, to predict traveler LOS on urban streets for 7. Turning movements that exceed 20 percent of the total
auto, bicycle, and pedestrians. Transit does not use speed volume on the street;
for LOS at the urban street level. However the LOS thresholds 8. Queues at one intersection backing up to and interfering
for each mode were selected by committee and are not backed with the operation of an upstream intersection; and
up by research indicating comparability of LOS values across 9. Cross-street congestion blocking through traffic.
modes.
Modal Interactions: The HCM incorporates many but not
Transit TCQSM Critique
all of the potential cross-modal influences on level of service.
Exhibit 21 highlights the key LOS criteria for each mode. Exhibit 23 critiques the intermodal relationships in the
Exhibit 22 then shows how the various modes can affect each Transit Capacity and Quality of Service Manual.
of these key LOS criteria. National Multimodal Application: The TCQSM is de-
The HCM takes into account the effects of pedestrians, bi- signed to be applied nationally for transit only.
cycles, and transit on auto delay at signalized intersections. Level of Service from a Traveler's Perspective: The
The signalized intersection delay in turn affects the estimated TCQSM LOS measures are based on surveys that identified
mean speed of through traffic on the urban street. The mean service factors important to traveler perceptions. The LOS
speed is the LOS criterion for an urban street in the HCM. E/F thresholds were set based on a project team/project panel
Higher auto volumes indirectly affect bicycle and pedes- consensus of undesirable service from a passenger stand-
trian LOS in the HCM method by affecting the signal timing point; the other thresholds ideally represent points where a
at the intersections. Longer cycle lengths and longer red times noticeable change in service quality occurs (e.g., when no
would increase bicycle and pedestrian delay and reduce their more seats are left), and otherwise represent even ranges of
level of service on the street. the service measure between LOS A and LOS F.
Higher auto volumes would indirectly affect transit relia- Applicable to Urban Streets: The TCQSM is oriented to
bility by increasing the probability of congestion, but the the transit service features, not the street facility. LOS meas-
HCM provides no method for estimating this effect. Thus the ures are provided for stops, routes, and the system as a whole.
effect of auto volumes on transit LOS cannot currently be The measures must be adapted for use on a specific street
accounted for using the available HCM procedures. facility.
The effects of pedestrians on bicycle level of service and the Considers All Factors Within Right of Way: The TCQSM
effects of bicycles on pedestrian level of service are accounted does not currently provide a methodology for taking into
for in the analysis of off-street facilities, but not for on-street account the effects of street facility characteristics on transit
facilities in the HCM. LOS. Walk and drive accessibility are currently not included
Higher transit volumes, by reducing capacity and increas- in bus stop level of service. No methodology is currently
ing congestion, can adversely affect bicycle and pedestrian available for estimating the effect of traffic congestion and
LOS in the HCM method by affecting the cycle length and red signal operation on transit service reliability.
times at signalized intersections. Safety and Economic Factors: Safety and economic factors
LOS Reflects All Movements: The HCM focuses on pre- are not included in the LOS methodology.
dicting urban street LOS only for the through movement for Comparable Modal LOS: The TCQSM focuses on transit.
auto, bicycle, and pedestrian. The transit LOS includes any The selected service measures are specific to transit and are
service on the street and at each stop. not comparable with those for other modes.
Averaging LOS Across Modes: The HCM does not aver- Modal Interactions: The TCQSM incorporates many but
age LOS across modes. not all of the potential cross-modal influences on level of
HCM Limitations: The HCM lists nine conditions (p. 15-1) service. Exhibit 23 shows how the various modes can affect
that are not accounted for in the current urban streets method- the key LOS criteria for transit.
ology for auto LOS: LOS Reflects All Movements: The transit LOS includes
any service on the street and at each stop.
1. Presence or lack of on-street parking; Averaging LOS Across Modes: The TCQSM does not
2. Driveway density or access control; average LOS across modes.
