1
Solution Space
In this chapter, we first present the solution space for the problem at hand. It consists of
a list of measures that may be implemented to improve the accessibility of Nijmegen
centre from the north. This list follows a structure based on a set of solution directions
which has been derived from the main conclusions of the problem analysis. The solution
space does not contain any thorough evaluation of the effects or feasibility of the
measures included.
Second, we select the measures from the solution space that are considered more
suitable for implementation, according to the evaluation criteria (accessibility,
environment, safety and costs) and the stakeholders’ positions.
1.1
Solution directions
The goal of this research project is to improve the transport accessibility of the city
center for car travelers using the Waalbrug route. To achieve that goal, severity of
congestion (which is related to the I/C ratio) must be reduced in order to reduce delays1.
Therefore, the first step in the process of developing solution directions was to identify
ways to reduce the I/C ratios along the Waalbrug route (see Fig. 1). The I/C ratio can be
influenced by:

Reducing traffic intensities on the route

Increasing the capacity of certain road stretches along the route
Reducing intensities and/or increasing capacities (especially on the route’s bottlenecks2)
could potentially lead to lower delays and hence improved accessibility.
Improve the accessibility of
Nijmegen centre from the North
(route using the Waalbrug)
Reducing car intensity
on the route
Public Transport
Increasing capacity
of the route
Demand, traffic and
parking policy
Road
infrastructure
Figure 1-1 Solution directions
The second step in the process of developing solution directions was to identify the
types of measures that could influence traffic intensity and/or capacity on the Waalbrug
route (see Figure 1-1). Those types of measures are:
1
Travel time delays increase more than proportionally when the intensity/capacity ratio increases (BPR
function).
2
Because of the beta factor in the BPR function.
1) Measures aimed at improving public transport service. Regulation and infrastructure
measures aimed at improving public transport service can influence travelers’ mode
choice behavior and incentivize them to choose public transport or intermodal
(car+transit) routes instead of car routes to reach their destination. As a result of modal
shift, traffic intensities on the Waalbrug route would diminish (at least in the short term,
if no damping effects due to induced demand are taken into account).
2) Demand, traffic and parking policy measures. This class of measures includes demand
management, traffic management and parking management measures. Demand
management measures can help to reduce car intensity on the route in rush hours, by
limiting demand or by distributing demand over time. Traffic management measures
can influence both the capacity of the route (by smoothing traffic operations) and traffic
intensities (by diverting traffic or limiting traffic access to the route). Finally, parking
management measures can be used to reduce traffic intensities on the route (in the
short term) by diverting car drivers to specific parking facilities and take them out of the
main route.
3) Road infrastructure measures. Building new infrastructure or rearranging existing
infrastructure can help to increase the capacity of certain road segments along the
Waalbrug route, especially the main bottlenecks.
1.2
Generation of measures
The main conclusions of the problem analysis in combination with the solution
directions previously mentioned were used as the basis to generate a comprehensive
list of measures that may improve the transport accessibility of the city centre (see
Figure 1-2). However, at this stage, their effects or feasibility were not evaluated yet.
The list is the result of several brainstorming sessions.
Improve the accessibility of
Nijmegen centre from the North
(route using the Waalbrug)
Reducing car intensity
on the route
Public Transport
Increasing capacity
of the route
Demand, traffic and
parking policy
Road
infrastructure
1. Building new bus/tram lines
8. Road pricing
2. Improve existing bus/train services
2a. Increase commercial speed
2b. Increase frequencies
2c. Reduce access times
9. Smart pricing
14. Widen the Waalbrug
10. Dynamic Traffic Management measures
10a. Route guidance system
10b. Dynamic speed management
10c. Traffic lights management
10d. Ramp metering
15. Open Waalbrug’s side lanes to car traffic
3. Improve the Waalsprinter service
3a. Increase comfort
3b. Increase frequencies
4. Improve PT fare system
5. Provide new Park & Ride facilities
13. Build a new bridge to cross the river
16. Reduce/remove conflicts between traffic
flows
16a. Reduce/remove conflicts on K. Traianusplein
16b. Reduce/remove conflicts on the Singels
11. Provide better parking information and
guidance
12. Improve parking fare system
6. Ferry system
7. Improve image of PT
Figure 1-2 Solution Space
In the future, even though a new bridge will be built (Stadsbrug), it won't constitute an
attractive alternative route for car drivers traveling to/from Nijmegen centre, south and
east from/to the northern zones. As a result, the capacity of the Waalbrug route will still
not be sufficient to accommodate predicted car traffic demand in peak hours, and car
drivers will still experience important delays. By implementing demand management
measures based on the concepts of “road pricing” (penalizing car drivers for using the
route in peak hours) or “smart pricing” (rewarding car drivers for not using the route in
peak hours), car traffic intensities on the Waalbrug route could be more efficiently
distributed over time and hence be reduced during rush hours. Car traffic intensities
could also be reduced by means of route guidance systems, which can support drivers in
choosing quicker routes to their destination in case the Waalbrug route is too congested,
thus reducing traffic demand on this route. Other measures could be based on
modifying the parking fare system and providing better information about parking
availability and guidance; those measures could be used to divert car drivers to specific
parking facilities, thus getting them out of the Waalbrug route as soon as possible or
reducing the amount of traffic conflicting with traffic on the Singels. Currently, as a
result of imbalances between parking supply and demand in different zones of the city
centre and the surrounding areas, car drivers who come from different areas in
Nijmegen and want to park their vehicle in/near the city centre need to use the Singels
or cross them in order to reach the cheapest parking facility.
Measures aimed at improving public transport service can also help to reduce car traffic
intensities on the Waalbrug route. Although currently all northern zones have a PT
connection to the city centre, most of them are not competitive with car routes in terms
of travel costs. Providing new PT services (tram or bus lines) with faster and more direct
connections and/or improving the service quality of existing train and bus lines could
foster modal shift and decrease the car traffic intensities on the Waalbrug route. If new
PT were built, however, current plans to expand the PT network in the region in the
future (which especially improve the connections between the city centre and
Waalsprong, Elst and Arnhem South) should be taken into account. Key elements of
existing transit services that could be improved are: a) commercial speed, frequencies
and access times, for bus and train services; b) travel comfort and frequencies, for the
Waalsprinter. Currently, intermodal routes (car+Waalsprinter) are almost the only
routes including use of PT that are competitive with car routes in terms of travel costs.
In addition, car+Waalsprinter routes can be used by travelers from all northern origins,
so its potential number of users is very high. Therefore, they are the type of PT routes
that shows the highest potential to reduce car traffic intensities on the Waalbrug route.
Besides improving the Waalsprinter service, new Park & Ride facilities could be built in
order to make new intermodal routes available to car drivers. For example, one of such
intermodal routes could combine a ferry system with a new Park & Ride facility located
in Waalsprong, in the northern shore of the river. Other possible measures that could
lead to a higher usage of public transport and lower intensities on the Waalbrug are:
providing lower fares (possibly for certain user classes, routes and time periods) and
improving public transport’s image (in order to modify the inaccurate perceptions that
travelers might have with regard to the benefits of using certain public transport
services).
As already mentioned, the capacity of the Waalbrug route is not sufficient to
accommodate the predicted traffic demand. The Keizer Traianusplein is the main
bottleneck, although the capacity of the Waalbrug is also limited. The capacity of the
Singels is limited by the high number of conflicts between traffic streams. Several
measures could contribute to increase the capacity of the route. First, measures could
be implemented to reduce conflicts between traffic streams (e.g. by rearranging flow
directions or traffic lights sequences) or even completely remove them (e.g. via tunnels,
viaducts, etc); in this way, conflicts may be reduced/removed both on the Keizer
Traianusplein and the Singels. Second, the capacity of the Waalbrug could be
augmented by physically widening the bridge or by using its side lanes (currently used as
bus lane in direction south and as bicycle path in direction north) for car traffic. The
possibility of building an extra bridge crossing the Waal could also be considered. Third,
dynamic traffic management measures such as ramp metering and dynamic speed
management could be used to increase the capacity of route segments that are
freeways (such as the Prins Mauritssingel and the Waalbrug).
1.3
Selection of measures
After defining the solution space, we selected only those measures that are more
suitable for implementation according to the criteria defined in Chapter 4 (accessibility,
environment, safety and costs) and the stakeholders’ positions. Indeed, several actors
have an interest in improving the accessibility of Nijmegen centre, and their support is
crucial for the viability of the solutions to be implemented. In addition, some of the
solutions have been discarded because the local government has already implemented
similar measures or it is going to do so in the near future (see Table 1-1).
Table 1-1 Selected and discarded alternatives
#
Public
transport
Demand,
traffic and
parking policy
Road
infrastructure
Measure
Reasons
Selected?
1
Building new bus/tram lines
No
Future HOV plans
2
Improve existing bus/train
services
No
Future HOV plans
3
Improve the Waalsprinter
service
Yes
The WS has the highest potential to attract
car users and is connected to all northern
zones
4
Improve PT fare system
No
Financial difficulties
5
Provide new Park & Ride
facilities
No
Competition with existing P&R
6
Ferry system
No
Long sailing route to cross dike, not
competitive
7
Improve image of PT
No
Beyond the scope of the project
8
Road pricing
No
Politically difficult to implement
9
Smart pricing
No
High costs, not sustainable
10a
Route guidance system
No
10b
Dynamic speed management
No
10c
Traffic lights management
Yes
10d
Ramp metering
No
11
Provide better parking
information and guidance
Yes
12
Improve parking fare system
Yes
13
Build a new bridge to cross the
river
No
High costs, lack of support from stakeholders
14
Widen the Waalbrug
No
High costs, lack of support from stakeholders
Yes
Increasing capacity of the Waalbrug
Yes
Increasing capacity on the main bottleneck
No
Not feasible, creation of new conflicts
15
16a
16b
Open Waalbrug's side lanes to
car traffic
Reduce/remove conflicts on K.
Traianusplein
Reduce/remove conflicts on the
Singels
Complex, does not fit into research
framework
Marginal effect expected (max.speed =
50km/h)
Increasing capacity of the K. Traianusplein
and the Singels at low cost
Ramps are not the main problem
Possibility to influence car travelers' route
choice behavior
Possibility to influence car travelers' route
choice behavior
Discarded measures:
Measures 1 and 2 have not been selected because the local government already has
plans to build three HOV lines which will provide more competitive PT routes for people
traveling between the city centre and northern zones such as Waalsprong, Elst, Bemmel
or Arnhem South. This new lines will also improve the competitiveness of some of the
existing PT routes, such as the train route between Arnhem South and Nijmegen centre
(for which the access time will be diminish after building the HOV 2 bus connection).
Measure 3 has not been selected because lowering transit fares is a difficult measure to
implement. The main reason is that PT service is already publicly subsidized and
decreasing revenues may lead to financial viability problems.
Measures 4 and 5 have been discarded because providing new P&R facilities along the
route could be counter-productive, since the new facilities may compete for travelers
with the existing P&R at Ressen and negatively influence the use of the Waalsprinter
service. In the case of the ferry system, besides the reason mentioned above, the sailing
route is not direct enough as a result of the construction of a second dike in the
northern shore of the river Waal, which undermines the competitiveness of such a
service.
Measure 7 has been discarded because marketing measures are beyond the scope of
this research project.
Measure 8 has not been selected because a road pricing system is technically complex
and politically difficult to implement. Its effects are also uncertain, since Nijmegen is a
small city and the public transport network is not competitive enough.
Measure 9 was already implemented at the beginning of September 2009 reduce traffic
intensities during the reconstruction of the A325 and Prins Mauritssingel. The measure
was considered successful but it was very costly. Implementing such a measure on an
everyday basis would require high and constant investments in the following years;
therefore, it has been discarded.
Measure 10a has not been selected because its effects on accessibility are complex to
evaluate and because it is a measure that can be useful to deal with traffic demand
variability, which has not been analyzed in our project.
Measure 10b has been discarded because its effects are expected to be marginal due to
the fact that the maximum speed on the route’s bottlenecks (Keizer Traianusplein and
Waalbrug) is very low (50km/h).
Measure 10d has not been selected because ramps and the weaving movements
associated with them are not the main element limiting the capacity of the Waalbrug
route’s bottlenecks, thus the potential effects of ramp metering are assumed to be
marginal.
Measures 13 and 14 have been discarded because of the high investment costs and the
lack of support from the main actors involved. They are not desired solutions for the
local government, especially building an additional bridge, since a new bridge is already
planned (Stadsbrug). Moreover, building an extra bridge would have high investment
costs3. The environmental groups are also against investing in more road traffic
infrastructure, although the associations of entrepreneurs of the city center back
infrastructure measures.
Measure 16b has been discarded for two main reasons. First, it is hard to reduce
conflicts between traffic streams on the Singels without creating new ones. Second,
reducing conflicts would most likely involve major changes on the road layout and this is
3
The cost of the Stadsbrug is estimated to 90 million euro.
against the interests of the main stakeholders, who wish to preserve the historic
characteristics of the Singels.
Selected measures:
Measure 3 has been selected because improving the Waalsprinter service is a measure
which has a high potential to reduce car traffic intensities on the Waalbrug route, thus
relieving congestion. Moreover, it would contribute to improve accessibility of Nijmegen
center by public transport, which is a strong interest of most of the stakeholders. Also, it
is a non infrastructural measure with relatively low investment costs. Improving the
Waalsprinter service can potentially score high on criteria such as travel costs, reliability,
environment and costs.
Measure 10c is selected because one of the main factors limiting the capacity of the
Waalbrug route’s bottlenecks is the waiting time due to red phases of traffic lights (in
Keizer Traianusplein and Singels). Optimizing traffic lights sequences in key intersections
(in combination with measures to remove/reduce conflicts) could lead to smoother
traffic flow, increased capacity and decreased congestion severity, and therefore higher
accessibility. This is a non-infrastructural measure and its costs are low, so it could easily
be accepted by the main stakeholders.
Measures 11 and 12 are selected because a combination of both offers the possibility of
guiding car drivers who are looking for parking to specific garages in such a way that
they leave the Waalbrug route as soon as possible (if they come from the north) or they
do not cross the Singels (if they come from the south). The stakeholders would most
likely support such a measure, as it is a soft measure that does not involve building new
infrastructure and does not have high investment costs, while it could contribute to
lower traffic intensities in the Waalbrug route and reduce conflicts with crossing traffic.
Measure 15 is selected because the current capacity of the Waalbrug is deemed to be
insufficient and it constitutes one of the main bottlenecks in the route, while there are
still two side lanes that could be used by car traffic. These two lanes are currently used
as bus lane in direction south and as bicycle path in direction north. This measure does
not involve building new infrastructure (only rearranging the layout), therefore its costs
would not be high. However, opening the side lanes to car traffic means that cyclists and
public transport would be negatively affected. As a result, this measure might generate
controversy among stakeholders.
Measure 16a has been selected because it can contribute to increase the capacity of
Keizer Traianusplein, which has been identified as the main bottleneck in the Waalbrug
route, at moderate investment costs. The idea is to smooth traffic flow to the Singels by
removing some conflicts and reducing others. Most of the stakeholders would probably
support the implementation of this measure. Although it may involve building more
infrastructure, the construction costs would be moderate and no extra land would be
needed. Furthermore, implementation of this measure would not change the
characteristics of the Singels, which is in line with the interests of not only the local
government, but also the environmental groups and political parties. Environmental
groups may oppose this measure because it involves building more infrastructure for
road transport, while they advocate for promoting alternative modes of transportation.