**6. Masterplan Leidsche Rijn**

28 Urban Development

four decades of spatial planning, the overall concept of how the urban areas, open spaces

and infrastructure of the Randstad related to each other had fundamentally changed.

Fig. 4. The shrinking boundaries of the Green Heart (Pieterse et al, 2005)

Leidsche Rijn is one of the most prominent products of the VINEX-report and reflects much of the developments that took place elsewhere in the Randstad. Leidsche Rijn expands the city of Utrecht (313.000 inhabitants) with 20 to 30.000 housing units, a large urban park and even larger employment areas. The development annexes the villages of Vleuten en De Meern. By doing so it almost doubles the urban footprint of the municipality of Utrecht. The larger Utrecht region had developed according a decentralised poly-centric model using new towns to accommodate the demand for high quality living in the region. It was a response to the concern that cities would become too large, too congested, too polluted. The Utrecht region witnessed the construction of two successful new towns: Nieuwegein (61.000 inhabitants) and Houten (48.000 inhabitants), separated from mother city Utrecht by a orbital motorway. Houten became a poster-boy for sustainable transport with its clever combination of transit-oriented development and a sophisticated bicycle network. The construction of the motorway network that connected the various cities and towns in the decentralised Randstad infrastructure didn't pose any difficulties for development of Nieuwegein and Houten. Motorways were in the 1970s still lean and mean. Their environmental impact was limited while the space between Utrecht and its new towns was

**5. Leidsche Rijn** 

superfluous.

In the early 1990s, a young urban planning firm received the commission to develop a master plan for Utrecht's new VINEX development Leidsche Rijn. The office was by then know as Max 1, currently as Maxwan. Maxwan proposed a different direction than most urban planners tended to pursue. Usually planners pay close attention to the environmental constraints of a site and use them as a starting point, trying to keep housing and other soft functions (such as education and care facilities) at a secure distance from major arteries or other producers of noise, air pollution and safety issues. This explains why in the Dutch practice green spaces are often used to fill up the gap between infrastructure and residential areas. But as a result, those green spaces often end up fragmented, noisy, polluted and not well suited to the recreational purposes that green spaces are mostly associated with.

Fig. 5. Leidsche Rijn with (left) and without (right) a tunnel solution (Maxwan, 2009)

Leidsche Rijn: Balancing the Compact City with the Randstad Motorway Network 31

for instance, without a decent road connection for a period of four years. The indirect economic damage would be so extensive that the ministry is not willing to take any chances. Thus, it banned the transportation of the most damaging dangerous goods from its tunnels (Directie Transportveiligheid, 1997). The multifunctional tunnel at Leidsche Rijn seemed to violate this regulation. The development of the Leidsche Rijn project, however, was in such an advanced stage that simply banning the tunnel was no longer feasible politically. A

In response to the safety concerns regarding the transport of dangerous goods, the Ministry of Transport, Public Works and Water Management opted to replace the full tunnel with a series of three shorter tunnels. This would reduce the impact of the most extreme anticipated scenarios on the A2 motorway users. Shorter tunnels contain fewer people, thus reducing the maximum number of potential causalities. The Ministry also opposed the idea of a 'floating tunnel' along a new alignment. The idea was not considered technically feasible. A fully submerged tunnel was out of the question because of the high ground water level that increases the cost to build such a structure. The construction of aboveground

The tight integration between urban development and road expansion required the Master Plan to be adjusted. Breaking up the tunnel meant that the environmental impact of the motorway would be felt in the area, noise and air pollution would be especially prominent. Raising the roof of the tunnel to a level of 6.5 metres above the surrounding area meant that the tunnel would function as a physical barrier. A preliminary concept responding to these issues, the Creative Alternative Integration A2 / Leidsche Rijn, was subsequently included in a revised master plan: the Ontwikkelingsvisie Leidsche Rijn Utrecht (Projectbureau Leidsche Rijn, 1996). It became the first major revision of the Masterplan and the tunnel

The 'Creative Alternative' consisted of three short tunnels, measuring 450 m, 408 m and 188 m. The Ministry did not allow housing to be built on top of these sections; instead, the area is designated for recreational purposes. Noise barriers would have to be used to reduce the

tunnels next to the current A2 emerged as the preferable solution.

Fig. 6. Creative Alternative: cross-sections (Maxwan, 1998).

environmental impact along the open sections.

different solution had to be developed.

concept.

Maxwan proposed to implement an innovative approach, like shifting the course of the motorway while at the same time tunnelling it. The company received that approval, and in 1995 delivered its Masterplan Leidsche Rijn, commissioned by the City of Utrecht. Therefore, the city of Utrecht proposed its Master Plan Leidsche Rijn to contain the noise and air pollution of the A2 motorway with a two-kilometre tunnel situated a few hundred meters from its original alignment in 1995 (Projectbureau Leidsche Rijn, 1995). The tunnel was partly suppressed with the assumption that a tunnel in the local soft soil conditions (with a high ground water level) would be cheaper to build as a 'floating construction' than as a submerged tunnel or as a full-fledged land tunnel. In addition, a suppressed tunnel is beneficial because it does not function as a barrier between the existing city of Utrecht and the new Leidsche Rijn development. Encapsulating the motorway allowed Maxwan to built housing and city centre functions next to the motorway. This allowed to plan a large urban park right at the heart of the development site where all residents could easily access it and not be burdened by noise or air pollution.

### **7. Safety concerns and the project's first revision**

Not long after the Masterplan Leidsche Rijn proposed its tunnel solution, concerns were voiced regarding the internal and external safety of the Landtunnel Utrecht that was such an integral part of the overall Master Plan Leidsche Rijn. Safety experts from the Construction Department of the Directorate General for Public Works and Water Management (part of the overall Ministry of Transport, Public Works and Water Management) pointed out that constructing a tunnel in the A2 would violate the existing rules and regulations for the transportation of dangerous goods, especially the transport of liquid flammable gasses, a category that contains predominately Liquefied Petrol Gas or LPG (Rijkswaterstaat Bouwdienst, 1996).

The Netherlands had many road tunnels by the late 20th century, and the majority were motorway tunnels that crossed one of the many waterways in the delta of the Rhine and Meuse rivers. Compared to tunnels in the mountainous parts of Europe, these tunnels are short in length. The fully enclosed sections of these tunnels often measure less than thousand metres. On the other hand, these tunnels tend to be rather wide. Tunnels with four lanes in each direction are not the exceptions. Their vulnerability does not stem from their length, but from the large volume of traffic that uses them and from their strategic position under water.

The general rule in the Netherlands is that all transportation of dangerous goods occurs on the motorway network because motorways provide higher levels of road safety. There is an exception to this rule. When a tunnel can be bypassed by using a bridge, then the use of that bridge is preferable. The bridge should be used, even if it increases the external risk for local inhabitants. This exception exists because of the economic risks involved in losing a tunnel. A scenario that includes the transport of dangerous goods could develop into an accident that could effectively put a tunnel permanently out of use. A truck carrying LPG could cause a problem such as a boiling liquid expanding vapour explosion (BLEVE). Although the chance that such a scenario develops may be remote, the possible impact of the scenario is devastating and, therefore, poses a considerable risk (Molag, 1998). It is unrealistic to expect that an underwater tunnel damaged in such an event could be repaired. It would become necessary to build a new one. Such a scenario could leave the Rotterdam Harbour,

Maxwan proposed to implement an innovative approach, like shifting the course of the motorway while at the same time tunnelling it. The company received that approval, and in 1995 delivered its Masterplan Leidsche Rijn, commissioned by the City of Utrecht. Therefore, the city of Utrecht proposed its Master Plan Leidsche Rijn to contain the noise and air pollution of the A2 motorway with a two-kilometre tunnel situated a few hundred meters from its original alignment in 1995 (Projectbureau Leidsche Rijn, 1995). The tunnel was partly suppressed with the assumption that a tunnel in the local soft soil conditions (with a high ground water level) would be cheaper to build as a 'floating construction' than as a submerged tunnel or as a full-fledged land tunnel. In addition, a suppressed tunnel is beneficial because it does not function as a barrier between the existing city of Utrecht and the new Leidsche Rijn development. Encapsulating the motorway allowed Maxwan to built housing and city centre functions next to the motorway. This allowed to plan a large urban park right at the heart of the development site where all residents could easily access it and

Not long after the Masterplan Leidsche Rijn proposed its tunnel solution, concerns were voiced regarding the internal and external safety of the Landtunnel Utrecht that was such an integral part of the overall Master Plan Leidsche Rijn. Safety experts from the Construction Department of the Directorate General for Public Works and Water Management (part of the overall Ministry of Transport, Public Works and Water Management) pointed out that constructing a tunnel in the A2 would violate the existing rules and regulations for the transportation of dangerous goods, especially the transport of liquid flammable gasses, a category that contains predominately Liquefied Petrol Gas or LPG (Rijkswaterstaat

The Netherlands had many road tunnels by the late 20th century, and the majority were motorway tunnels that crossed one of the many waterways in the delta of the Rhine and Meuse rivers. Compared to tunnels in the mountainous parts of Europe, these tunnels are short in length. The fully enclosed sections of these tunnels often measure less than thousand metres. On the other hand, these tunnels tend to be rather wide. Tunnels with four lanes in each direction are not the exceptions. Their vulnerability does not stem from their length, but from the large volume of traffic that uses them and from their strategic position

The general rule in the Netherlands is that all transportation of dangerous goods occurs on the motorway network because motorways provide higher levels of road safety. There is an exception to this rule. When a tunnel can be bypassed by using a bridge, then the use of that bridge is preferable. The bridge should be used, even if it increases the external risk for local inhabitants. This exception exists because of the economic risks involved in losing a tunnel. A scenario that includes the transport of dangerous goods could develop into an accident that could effectively put a tunnel permanently out of use. A truck carrying LPG could cause a problem such as a boiling liquid expanding vapour explosion (BLEVE). Although the chance that such a scenario develops may be remote, the possible impact of the scenario is devastating and, therefore, poses a considerable risk (Molag, 1998). It is unrealistic to expect that an underwater tunnel damaged in such an event could be repaired. It would become necessary to build a new one. Such a scenario could leave the Rotterdam Harbour,

not be burdened by noise or air pollution.

Bouwdienst, 1996).

under water.

**7. Safety concerns and the project's first revision** 

for instance, without a decent road connection for a period of four years. The indirect economic damage would be so extensive that the ministry is not willing to take any chances. Thus, it banned the transportation of the most damaging dangerous goods from its tunnels (Directie Transportveiligheid, 1997). The multifunctional tunnel at Leidsche Rijn seemed to violate this regulation. The development of the Leidsche Rijn project, however, was in such an advanced stage that simply banning the tunnel was no longer feasible politically. A different solution had to be developed.

In response to the safety concerns regarding the transport of dangerous goods, the Ministry of Transport, Public Works and Water Management opted to replace the full tunnel with a series of three shorter tunnels. This would reduce the impact of the most extreme anticipated scenarios on the A2 motorway users. Shorter tunnels contain fewer people, thus reducing the maximum number of potential causalities. The Ministry also opposed the idea of a 'floating tunnel' along a new alignment. The idea was not considered technically feasible. A fully submerged tunnel was out of the question because of the high ground water level that increases the cost to build such a structure. The construction of aboveground tunnels next to the current A2 emerged as the preferable solution.

The tight integration between urban development and road expansion required the Master Plan to be adjusted. Breaking up the tunnel meant that the environmental impact of the motorway would be felt in the area, noise and air pollution would be especially prominent. Raising the roof of the tunnel to a level of 6.5 metres above the surrounding area meant that the tunnel would function as a physical barrier. A preliminary concept responding to these issues, the Creative Alternative Integration A2 / Leidsche Rijn, was subsequently included in a revised master plan: the Ontwikkelingsvisie Leidsche Rijn Utrecht (Projectbureau Leidsche Rijn, 1996). It became the first major revision of the Masterplan and the tunnel concept.

Fig. 6. Creative Alternative: cross-sections (Maxwan, 1998).

The 'Creative Alternative' consisted of three short tunnels, measuring 450 m, 408 m and 188 m. The Ministry did not allow housing to be built on top of these sections; instead, the area is designated for recreational purposes. Noise barriers would have to be used to reduce the environmental impact along the open sections.

Leidsche Rijn: Balancing the Compact City with the Randstad Motorway Network 33

Fig. 8. The Creative Alternative with horizontal cantilevers (Maxwan, 1998).

contained, among other things, the results of two interesting partial studies.

Fig. 9. Masterplan Leidsche Rijn (Utrecht, 2011).

In 1998, the Projectbureau Leidsche Rijn published an additional investigation into the requirements to integrate the A2 in Leidsche Rijn from an urban perspective (Maxwan, 1998). The project bureau's objective was to optimise the Creative Alternative. Its report

Fig. 7. Creative Alternative: alignment (Maxwan, 1998).

Fig. 7. Creative Alternative: alignment (Maxwan, 1998).

Fig. 8. The Creative Alternative with horizontal cantilevers (Maxwan, 1998).

In 1998, the Projectbureau Leidsche Rijn published an additional investigation into the requirements to integrate the A2 in Leidsche Rijn from an urban perspective (Maxwan, 1998). The project bureau's objective was to optimise the Creative Alternative. Its report contained, among other things, the results of two interesting partial studies.

Fig. 9. Masterplan Leidsche Rijn (Utrecht, 2011).

Leidsche Rijn: Balancing the Compact City with the Randstad Motorway Network 35

Fig. 11. Sloping as a means to integrate the Landtunnel Utrecht at Leidsche Rijn (Maxwan,

The other, somewhat simple, study visualised the use of sloping as a means to integrate the 'hollow dike' with its surrounding area. The study concluded that, along the motorway, a slope with an angle of three percent and a length of 210 metres was necessary to minimise the impact of the height difference introduced by the physical height of the land tunnel. The extensive slope was required to facilitate soft modes of transportation (walking and cycling) between the VINEX-development and the city of Utrecht. The exploration also showed that

In a parallel process, the municipality of Rotterdam also called for a multifunctional tunnel to cover a section of the A15 motorway in 1998: the Green Link. The situation is comparable as the A15 separates Rotterdam from its largest VINEX development: Carnisselande. The A15 is a section of the Rotterdam Ring that connects the Rotterdam harbour area to its hinterland. The municipality of Rotterdam faced a similar line of argument as that by Utrecht. The regional Directorate General for Public Works and Water Management (RWS Zuid-Holland) told the urban planning department of the Municipality of Rotterdam that a tunnel would not be feasible because of the need to transport dangerous goods along the A15. RWS Zuid-Holland only allowed small tunnel sections of 80 metres, with a minimal spacing of 50 metres between covered sections. Rotterdam called in the support of the Delft University of Technology (TU Delft). The city was not convinced that the construction proposed by RWS Zuid-Holland could effectively reduce the environmental impact of the A15 motorway that had to be extended to five lanes in each direction. It requested an indepth investigation into the safety issues regarding motorway tunnels. The A15 presented an ideal showcase. The A15 accommodates an enormous volume of dangerous goods that flow directly from the (petro) chemical industry in the Rotterdam Mainport. There are 200,000 transports yearly, which greatly exceeds the volume that passes Leidsche Rijn. If a solution could be found here, it would be a true breakthrough. This pilot programme required TU Delft to develop regular exchanges with Rotterdam's Urban Planning Department, the Construction Department of the Directorate General for Public Works and

a partially submerged tunnel could do with half of that sloping area, or 105 metres.

Water Management (RWS Bouwdienst) and the Rotterdam Fire Brigade.

1998).

**8. Green Link A15** 


Fig. 10. Noise levels of the Landtunnel Utrecht using different sets of noise barriers and cantilevers, image by TNO (Maxwan, 1998).

The first study (conducted by TNO) looked at the noise production of the motorway and the impact of using different sets of noise barriers and cantilevers. It appeared that the use of a two-layered porous asphalt construction in combination with horizontal cantilevers promised the best results.

Fig. 11. Sloping as a means to integrate the Landtunnel Utrecht at Leidsche Rijn (Maxwan, 1998).

The other, somewhat simple, study visualised the use of sloping as a means to integrate the 'hollow dike' with its surrounding area. The study concluded that, along the motorway, a slope with an angle of three percent and a length of 210 metres was necessary to minimise the impact of the height difference introduced by the physical height of the land tunnel. The extensive slope was required to facilitate soft modes of transportation (walking and cycling) between the VINEX-development and the city of Utrecht. The exploration also showed that a partially submerged tunnel could do with half of that sloping area, or 105 metres.

#### **8. Green Link A15**

34 Urban Development

Fig. 10. Noise levels of the Landtunnel Utrecht using different sets of noise barriers and

The first study (conducted by TNO) looked at the noise production of the motorway and the impact of using different sets of noise barriers and cantilevers. It appeared that the use of a two-layered porous asphalt construction in combination with horizontal cantilevers

cantilevers, image by TNO (Maxwan, 1998).

promised the best results.

In a parallel process, the municipality of Rotterdam also called for a multifunctional tunnel to cover a section of the A15 motorway in 1998: the Green Link. The situation is comparable as the A15 separates Rotterdam from its largest VINEX development: Carnisselande. The A15 is a section of the Rotterdam Ring that connects the Rotterdam harbour area to its hinterland. The municipality of Rotterdam faced a similar line of argument as that by Utrecht. The regional Directorate General for Public Works and Water Management (RWS Zuid-Holland) told the urban planning department of the Municipality of Rotterdam that a tunnel would not be feasible because of the need to transport dangerous goods along the A15. RWS Zuid-Holland only allowed small tunnel sections of 80 metres, with a minimal spacing of 50 metres between covered sections. Rotterdam called in the support of the Delft University of Technology (TU Delft). The city was not convinced that the construction proposed by RWS Zuid-Holland could effectively reduce the environmental impact of the A15 motorway that had to be extended to five lanes in each direction. It requested an indepth investigation into the safety issues regarding motorway tunnels. The A15 presented an ideal showcase. The A15 accommodates an enormous volume of dangerous goods that flow directly from the (petro) chemical industry in the Rotterdam Mainport. There are 200,000 transports yearly, which greatly exceeds the volume that passes Leidsche Rijn. If a solution could be found here, it would be a true breakthrough. This pilot programme required TU Delft to develop regular exchanges with Rotterdam's Urban Planning Department, the Construction Department of the Directorate General for Public Works and Water Management (RWS Bouwdienst) and the Rotterdam Fire Brigade.

Leidsche Rijn: Balancing the Compact City with the Randstad Motorway Network 37

Although the Green Link was ultimately not built, the publication of the concept by TU Delft, including the results of RWS' own analysis and the Category-0 requirements by the Rotterdam Fire Brigade, made it clear for the first time in the Netherlands that transport of dangerous goods does not rule out the implementation of multifunctional tunnels. That insight was still contested by the Directorate-General for Freight Transport of the Ministry of Transport, Public Works and Water Management at that time. The issue continued to assert pressure on proposed multifunctional tunnels, such as the Landtunnel Utrecht.

In the year 2000, new EU regulations on air quality were introduced and caused a stir in the Netherlands. Much of the country suffered from high levels of background pollution that were near or above the future limits set by the EU. Those limits were easily exceeded near major motorways or other sources of air pollution. The technology institute TNO delivered the first set of air quality calculations (nitrogen dioxide and particulate matter) for the A2 based on the new requirements. The calculations showed that wider than expected areas along the open parts of the land tunnel at Leidsche Rijn could not be used for residential purposes. This would mean a significant breach of the urban quality of the area and an undesirable decrease in the number of housing units that could be built. The municipality of Utrecht, the project bureau Leidsche Rijn, RWS and the Ministry of Housing, Spatial Planning and the Environment jointly commissioned a study by ARCADIS and the Architectengroep. The final report of that study was delivered in December 2001 (Brouwer, Rijnboutt, 2001). Three partial studies by TNO and ARCADIS were included in the study that investigated air pollution, safety and noise. The study unexpectedly concluded that noise was the environmental impact with the largest consequences for land use in Leidsche Rijn, rather than air quality or safety. The ARCADIS/Architectengroep study evaluated five alternatives: 1] the original 'Creative Alternative', 2] the 'Creative Alternative' with horizontal cantilevers over the road, 3] an alternative that covered only the northern part of the alignment, 4] an alternative based on short tunnels with lengths of just 80 metres, 5] a

**9. Weighing five alternatives followed by a final concept revision** 

fully covered surface tunnel.

Fig. 13. Alternatives 1, 2, 3, 4 and 5 (van der Hoeven, 2010).

The Rotterdam Fire Brigade proposed implementing a sprinkler system in the tunnel to rule out the development of any scenario that starts with a regular fire and could potentially develop into a more severe accident. In addition, TU Delft proposed containing the impact of any explosive scenario by physically separating the tunnel's tubes. Unfortunately the models that were used at that time to assess tunnel safety in the Netherlands did not allow the incorporation of any claims about the effectiveness of a sprinkler system or an improved tunnel tube configuration. Though potentially effective in practice, these measures had no impact on the outcome of the assessment itself. To influence the assessment's outcome, it appeared more important to consider the likely, but less extreme, scenarios in which regular trucks were involved, such as a 'large vehicle fire'. Isolating lorries in a separate tube from the rest of the traffic results in a notable reduction in the number of deaths due to such events, offsetting the increased mortality in the case of unlikely but more extreme events. Given that the new tunnels were built on land, it seemed that the potential economic risk was manageable as well. In the unlikely scenario that the roof is blown off, the infrastructure could be 'easily' repaired. Because urban tunnels are not situated under water, they are unlikely to lose their functionality as a small 'polder' (Hoeven, 1999). The RWS Bouwdienst provided the calculations and confirmed that the concept was sound (Rijkswaterstaat Bouwdienst, 1998). The Rotterdam Fire Brigade formulated requirements for a Category-0 tunnel. This concept did not ban the transportation of any type of dangerous goods through the tunnel but emphasised the necessity of prevention and automated repression (Broekhuizen, 1998).

Fig. 12. Green Link A15 (Hoeven, 1999)

The Rotterdam Fire Brigade proposed implementing a sprinkler system in the tunnel to rule out the development of any scenario that starts with a regular fire and could potentially develop into a more severe accident. In addition, TU Delft proposed containing the impact of any explosive scenario by physically separating the tunnel's tubes. Unfortunately the models that were used at that time to assess tunnel safety in the Netherlands did not allow the incorporation of any claims about the effectiveness of a sprinkler system or an improved tunnel tube configuration. Though potentially effective in practice, these measures had no impact on the outcome of the assessment itself. To influence the assessment's outcome, it appeared more important to consider the likely, but less extreme, scenarios in which regular trucks were involved, such as a 'large vehicle fire'. Isolating lorries in a separate tube from the rest of the traffic results in a notable reduction in the number of deaths due to such events, offsetting the increased mortality in the case of unlikely but more extreme events. Given that the new tunnels were built on land, it seemed that the potential economic risk was manageable as well. In the unlikely scenario that the roof is blown off, the infrastructure could be 'easily' repaired. Because urban tunnels are not situated under water, they are unlikely to lose their functionality as a small 'polder' (Hoeven, 1999). The RWS Bouwdienst provided the calculations and confirmed that the concept was sound (Rijkswaterstaat Bouwdienst, 1998). The Rotterdam Fire Brigade formulated requirements for a Category-0 tunnel. This concept did not ban the transportation of any type of dangerous goods through the tunnel but emphasised the necessity of prevention and automated repression

(Broekhuizen, 1998).

Fig. 12. Green Link A15 (Hoeven, 1999)

Although the Green Link was ultimately not built, the publication of the concept by TU Delft, including the results of RWS' own analysis and the Category-0 requirements by the Rotterdam Fire Brigade, made it clear for the first time in the Netherlands that transport of dangerous goods does not rule out the implementation of multifunctional tunnels. That insight was still contested by the Directorate-General for Freight Transport of the Ministry of Transport, Public Works and Water Management at that time. The issue continued to assert pressure on proposed multifunctional tunnels, such as the Landtunnel Utrecht.

#### **9. Weighing five alternatives followed by a final concept revision**

In the year 2000, new EU regulations on air quality were introduced and caused a stir in the Netherlands. Much of the country suffered from high levels of background pollution that were near or above the future limits set by the EU. Those limits were easily exceeded near major motorways or other sources of air pollution. The technology institute TNO delivered the first set of air quality calculations (nitrogen dioxide and particulate matter) for the A2 based on the new requirements. The calculations showed that wider than expected areas along the open parts of the land tunnel at Leidsche Rijn could not be used for residential purposes. This would mean a significant breach of the urban quality of the area and an undesirable decrease in the number of housing units that could be built. The municipality of Utrecht, the project bureau Leidsche Rijn, RWS and the Ministry of Housing, Spatial Planning and the Environment jointly commissioned a study by ARCADIS and the Architectengroep. The final report of that study was delivered in December 2001 (Brouwer, Rijnboutt, 2001). Three partial studies by TNO and ARCADIS were included in the study that investigated air pollution, safety and noise. The study unexpectedly concluded that noise was the environmental impact with the largest consequences for land use in Leidsche Rijn, rather than air quality or safety. The ARCADIS/Architectengroep study evaluated five alternatives: 1] the original 'Creative Alternative', 2] the 'Creative Alternative' with horizontal cantilevers over the road, 3] an alternative that covered only the northern part of the alignment, 4] an alternative based on short tunnels with lengths of just 80 metres, 5] a fully covered surface tunnel.

Fig. 13. Alternatives 1, 2, 3, 4 and 5 (van der Hoeven, 2010).

Leidsche Rijn: Balancing the Compact City with the Randstad Motorway Network 39

Wind does seem to have an impact, which can be seen in the higher concentrations on the east side of all alternatives. The length of the tunnel matters as well. The concentration of air pollution at the ends of the tunnel increases as the tunnel becomes longer. Two walls separate in alternative 2 the inside lanes from the outside lanes. The inside lanes, designed for local traffic, are fully covered by the cantilevers and, with the addition of the wall, effectively enclosed in a 1650 meters long tunnel. Compared to alternative 1, this results in increased emissions at the tunnel's ends, and reduced emissions near the open sections. Alternative 3 contains 40-meter high buildings bordering the open sections of the motorway; this alternative effectively reduces the air pollution without creating peak concentrations

A safety assessment was conducted by ARCADIS (ARCADIS, 2001). The ARCADIS study concludes that the existing laws and regulations, as well as the framework used in the assessment do not pose a major obstacle for any of the five alternatives. In all alternatives, the group risk that users of the motorway tunnel collectively faced stayed well below the

TNO converted its 1998 noise assessment into contours that could be displayed on maps that enabled TNO to calculate the surface of the area affected by noise levels of 50 and 55 dB (TNO TPD, 2001). An overview of the impact of the five alternatives on the surface of the development area, the loss of real estate revenue, and the loss of the number of housing units is presented. These figures belong to the 55 dB contours that require the maximal legal exemption from the Ministry of Spatial Planning, Housing and the Environment. The

Fig. 15. Table indicating lost development area, lost housing units and lost real estate revenue because of noise levels that exceed the 55 dB limit for each alternative (van der

The study also provided investment figures. The differences in the construction costs of the alternatives appear to be relatively small. The original Creative Alternative was estimated to cost 460 M€, while the optimised Creative Alternative (using horizontal cantilevers, as favoured by the Projectbureau Leidsche Rijn) was estimated to cost 501 M€ to build. A fully covered surface tunnel required an additional 10 M€ for a total of 511 M€. The fully covered

like those at the other end of the tunnel.

Hoeven, 2010).

indicative norm of 10-2/N2, despite the transport of LPG.

figures that belong to the 50 dB contours are considerably larger.

The new air quality assessment by TNO provided detailed insight in the diffusion of the emissions in the project area (TNO MEP, 2001). With more experience under the new regulations and an adjusted value for the background emission, each of the alternatives seemed to keep the nitrogen dioxide values below 40 µg/m3 at a distance of 50 metres from the road. Only the 1650-m long full-length tunnel (alternative 5) showed a small area where emissions peaked at 41 µg/m3. Presented in this chapter are the nitrogen dioxide diagrams for alternatives 1, 2, 3 and 5. Alternative 4 is not presented because it was not evaluated in the TNO study. TNO calculated emission levels at distances of 50 and 100 metres from the road. No calculations were made for the area above the tunnel. The fact that no emissions are displayed here does not mean that the area is not exposed. The impact of the noise barriers was taken into account in the study.

Fig. 14. Calculated nitrogen dioxide emissions alternatives 1, 2, 3 and 5 (van der Hoeven, 2010).

The new air quality assessment by TNO provided detailed insight in the diffusion of the emissions in the project area (TNO MEP, 2001). With more experience under the new regulations and an adjusted value for the background emission, each of the alternatives seemed to keep the nitrogen dioxide values below 40 µg/m3 at a distance of 50 metres from the road. Only the 1650-m long full-length tunnel (alternative 5) showed a small area where emissions peaked at 41 µg/m3. Presented in this chapter are the nitrogen dioxide diagrams for alternatives 1, 2, 3 and 5. Alternative 4 is not presented because it was not evaluated in the TNO study. TNO calculated emission levels at distances of 50 and 100 metres from the road. No calculations were made for the area above the tunnel. The fact that no emissions are displayed here does not mean that the area is not exposed. The impact of the noise

Fig. 14. Calculated nitrogen dioxide emissions alternatives 1, 2, 3 and 5 (van der Hoeven,

barriers was taken into account in the study.

2010).

Wind does seem to have an impact, which can be seen in the higher concentrations on the east side of all alternatives. The length of the tunnel matters as well. The concentration of air pollution at the ends of the tunnel increases as the tunnel becomes longer. Two walls separate in alternative 2 the inside lanes from the outside lanes. The inside lanes, designed for local traffic, are fully covered by the cantilevers and, with the addition of the wall, effectively enclosed in a 1650 meters long tunnel. Compared to alternative 1, this results in increased emissions at the tunnel's ends, and reduced emissions near the open sections. Alternative 3 contains 40-meter high buildings bordering the open sections of the motorway; this alternative effectively reduces the air pollution without creating peak concentrations like those at the other end of the tunnel.

A safety assessment was conducted by ARCADIS (ARCADIS, 2001). The ARCADIS study concludes that the existing laws and regulations, as well as the framework used in the assessment do not pose a major obstacle for any of the five alternatives. In all alternatives, the group risk that users of the motorway tunnel collectively faced stayed well below the indicative norm of 10-2/N2, despite the transport of LPG.

TNO converted its 1998 noise assessment into contours that could be displayed on maps that enabled TNO to calculate the surface of the area affected by noise levels of 50 and 55 dB (TNO TPD, 2001). An overview of the impact of the five alternatives on the surface of the development area, the loss of real estate revenue, and the loss of the number of housing units is presented. These figures belong to the 55 dB contours that require the maximal legal exemption from the Ministry of Spatial Planning, Housing and the Environment. The figures that belong to the 50 dB contours are considerably larger.


Fig. 15. Table indicating lost development area, lost housing units and lost real estate revenue because of noise levels that exceed the 55 dB limit for each alternative (van der Hoeven, 2010).

The study also provided investment figures. The differences in the construction costs of the alternatives appear to be relatively small. The original Creative Alternative was estimated to cost 460 M€, while the optimised Creative Alternative (using horizontal cantilevers, as favoured by the Projectbureau Leidsche Rijn) was estimated to cost 501 M€ to build. A fully covered surface tunnel required an additional 10 M€ for a total of 511 M€. The fully covered

Leidsche Rijn: Balancing the Compact City with the Randstad Motorway Network 41

fire resistance of the trucks that deliver LPG to gas stations, which reduces the likelihood of accidents involving these transports (Infrasite, 2006). The background levels of nitrogen dioxide and particulate matter were declining as a result of the imposed measures to meet

The final outcome of the Landtunnel Utrecht development may surprise. The urban planners of Maxwan had sided with the local authority of Utrecht for over a decade (1995- 2006) in a continuous struggle with the Ministry of Transport, Public Works and Water Management in order to achieve the Masterplan Leidsche Rijn as it was originally envisioned. It faced sustained opposition from that Ministry. The Ministry however is responsible for many policy objectives and comprises many departments. Maxwan and Utrecht may have failed to recognise who is foe and who is friend in this large organisation. In the discussions the author had with the urban planners of Maxwan it became clear that

The author was in 2000 consulted by the project manager of the regional Directorate General for Public Works and Water Management, responsible for the widening of the A2. The project manager was transparent about the fact that he opposed the overall concept of the Masterplan Leidsche Rijn. In his eyes Utrecht's compact city policy was little more than a strategy to annex its neighbouring municipality Vleuten-De Meern. However, once it would be decided to built the Landtunnel Utrecht, he felt it should be done properly as a fully covered tunnel. It should not be broken up in smaller segments or just be partially covered.

The Construction Department of the Directorate General for Public Works and Water Management had initially raised the red flag regarding safety. The director of that Department, Rinus Olierook, chaired during this time a committee that had to initiate a large scale programme investigating multifunctional land use, a programme that would later become Habiforum. He recognised Leidsche Rijn as a perfect showcase of that

Looking backwards the task to unite the different viewpoints in order to reach an joint agreement seemed less daunting than the decade of moving back and fourth may suggest. What could have caused it to take so long? The introduction of this chapter sketched the larger context in which the spatial developments in the Randstad took place. The latest stage in that development (VINEX) was a time in which the larger cities like Utrecht, The Hague and Rotterdam, and smaller cities such as Eindhoven, Amersfoort and Delft broke free from the boundaries that the 1970s motorway network had imposed on them. The urban footprint of these cities expanded over the motorways. With that the network that was carefully

The fight that enfolded in the case of Leidsche Rijn focused on details such as noise, air pollution and safety. That fight may not have been fought so hard if it did not represent a more fundamental discussion on accessibility. The motorway network was the designated

the classic polarity of municipality versus ministry dominated their viewpoint.

The author was not at liberty to share this information with Maxwan or Utrecht.

principle. He made that clear in an interview that was published by the author.

planned to bypass cities became part of many urban areas.

the new European limits.

**11. The bigger picture** 

**10. Friend or foe?** 

surface tunnel would allow more residential area to be developed than the other alternatives and less development area was exposed to noise levels over 50 and 55 dB. RWS ruled out residential development above the 13-hectare large tunnel surface, unlike the Donau-ufer Autobahn in Vienna. The full-length tunnel was, nevertheless, able to generate higher income for real estate development. Effectively, the financial differences between the optimised Creative Alternative (alternative 2) and the fully covered surface tunnel (alternative 5) disappeared altogether. The financial difference between the original Creative Alternative (alternative 1) and the fully covered surface tunnel was reduced to less than ten percent.


Fig. 16. Table indicating lost real estate revenue (55 dB), the required road investment and the sum of road investment and lost revenue for each alternative (van der Hoeven, 2010).

ARCADIS and the Architectengroep advised the decision takers to opt for any of the first three alternatives. They ruled out the alternative of a series of short tunnels that only covered a length of 80 metres because of its lacking spatial quality and the emission levels, although the TNO report did not explore this option. They also ruled out the fully covered surface tunnel because it was considered undesirable from the safety point of view, although the ARCADIS the report did not provide research-based evidence to substantiate such a claim.

In 2002, the government and the municipality of Utrecht reached a deal based on an optimised version of the Creative Alternative. The project's costs were finally assessed at 535 M€. The Ministry of Transport, Public Works and Water Management agreed to pay 323 M€. The Ministry of Housing, Spatial Planning and the Environment contributed 99 M€. The municipality, region and province of Utrecht agreed to add 83 M€ to the project's budget. Saving in other areas of the project generated an additional 30 M€. The landscaping of the surface tunnel's surrounding area could be realised with less excessive sloping (Nieuwsbank, 2002).

In 2006, just before the start of construction, the Directorate General for Public Works and Water Management and the municipality of Utrecht revised the tunnel concept one last time as they agreed to build a fully covered tunnel, without referring to potential safety or air quality issues. Meanwhile, an agreement was reached with the LPG sector to increase the fire resistance of the trucks that deliver LPG to gas stations, which reduces the likelihood of accidents involving these transports (Infrasite, 2006). The background levels of nitrogen dioxide and particulate matter were declining as a result of the imposed measures to meet the new European limits.
