WO2012045289A1

WO2012045289A1 - Roundabout for smooth and safe passing of priority vehicles and/or oversize load carrying vehicles and method of crossing such a roundabout

Info

Publication number: WO2012045289A1
Application number: PCT/CZ2011/000096
Authority: WO
Inventors: Petr NOVOTNÝ
Original assignee: Novotny Petr
Priority date: 2010-10-07
Filing date: 2011-10-04
Publication date: 2012-04-12
Also published as: CZ303027B6; SK50092013A3; CZ2010734A3

Abstract

Circuit crossroad comprising a roundabout (1 ) with a high central island (2) and roads (3,3 ',4,4') connected to the roundabout (1). In the central island (2) there is a crossing lane (5) of the central island (2) comprising at least one crossing lane extending slantwise across the central island (2). Warning traffic lights (6, 6') with remote control may be installed before the exits to the first road (3) and to the third road (3'). A priority vehicle (7) and/or a oversize load carrying vehicle (8) crosses the central island (2) on the crossing lane (5), whereas it first drives to the opposite direction on the first road (3) and enters the roundabout (1 ) via the exit to the first road (3). Traffic on the roundabout (1) is stopped at that time.

Description

ROUNDABOUT FOR SMOOTH AND SAFE PASSING OF PRIORITY VEHICLES AND/OR OVERSIZE LOAD CARRYING VEHICLES AND METHOD OF CROSSING SUCH A

ROUNDABOUT

Field of the invention

The invention relates to a crossroad with a so-called roundabout, the design of which should provide a smooth passing of priority vehicles or oversize load carrying vehicles. The invention relates to a smooth and safe passing of the roundabout by a priority vehicle or a oversize load carrying vehicle.

Background of the invention

The circuit crossroads consisting basically of roundabouts are increasingly important in modern project designs of traffic systems and roads. They benefit from, among others, improvement of smooth traffic as well as increase of safety due to the slowdown where the drivers can not see the crossroad due to high central island and must slow-down in order to give a way to a car coming from the left on the roundabout from side or opposite direction.

For the most common design, the roundabout is shaped to a circle creating a circuit way to which four two-lane roads are connected at approximately right angles, of which imaginary axes cross roughly in the centre of the centre island.

Triangle-shaped partitioning islands before entering to the roundabout usually separate the traffic lanes on the roads in opposite directions.

A disadvantage of commonly designed roundabouts is that the crossroads of smaller diameter make passing of long vehicles and oversize load carrying vehicles difficult or impossible. Should the traffic throughput need to be maintained also for these vehicles, the roundabout of big diameter must be designed, which increases -investment-casts-Another-disadvantage is that the priority vehicles, i.e. fire brigade^" vehicles (HZS), medical emergency vehicles (RZP) and police vehicles (P) are slowed down when entering to the roundabout identically to other vehicles with potential direct impact on life or health of a patient in case of RZP.

Should the priority vehicle pass the roundabout with emergency lights and sirens on, drivers of other vehicles usually stop on an unsuitable place, e.g. at exit from the roundabout and block the priority vehicles in passing. In case of the RZP vehicles, passing through a roundabout is rather difficult also because when passing the roundabout in straight direction, three rather sharp bends must be passed (right, left and right), which inclines the vehicle and so-called side acceleration with complications occurs and administration of a treatment to a patient during driving may be almost impossible.

To facilitate and ensure better passing of the priority vehicles and oversize load carrying vehicles through a roundabout in a straight direction, there are known roundabouts with circuit shape but the traffic lanes being the main road are connected to the roundabout outside the circuit's centre and therefore, their connecting line is in fact a straight chord at the edge part of the circuit that forms the roundabout. Although this project design of the roundabout allows accelerated passing of the priority vehicles as well as the oversize load carrying vehicles, the roundabout's safety component is lost here because the drivers approaching in the straight direction see the opposite direction on the main road, pass the roundabout without bending in fact and therefore, they tend to pass through the roundabout at higher speed and may overlook a driver approaching from the left to the roundabout and the safety risk of the roundabout increases. In addition, drivers in other directions must pass the roundabout through very long bend.

A quite different design of the roundabout is that the traffic lanes are connected to the roundabout at regular cross-like arrangement and therefore, their imaginary axes intersect roughly in the centre of the circuit, but the increased centre island has semicircular plan. The rest of the semi-circle consist of flat road, which can be used by both the priority vehicles as well as the oversize load carrying vehicles at straight direction, if needed. In fact, this design poses equal safety risks and disadvantages as the solution described above with the roundabout with asymmetrically arranged approaching traffic lanes.

The task of the invention is to design of a roundabout, that would remove the above stated deficiencies and increase safety of all road traffic participants, allowing for a faster passing of priority vehicles or oversize load carrying vehicles.

Summary of the invention

The roundabout for safe and smooth passing of the priority vehicles or the oversize load carrying vehicles consists of known circuit shaped way with a central island where at least three two-lane roads are connected to the roundabout. The subject- matter of the invention is that in the central island there is a crossing lane of the central island consisting of at least one lane slantwise across the central island from exit from the roundabout to the first road to the roundabout exit to at least third road in the order following from the entry to the roundabout on the first road. The basic idea of the design of the roundabout according to the invention is that the priority vehicles or the oversize load carrying vehicles passe the roundabout by crossing the central island, which is, however, designed so that view to the area after the roundabout is hindered and so that the safety parameters of the existing crossing are not reduced. This is achieved by slantwise placement of the crossing and arriving of a vehicle to the roundabout from the opposite direction, i.e. from the roundabout exit on the first road on which the vehicle is approaching.

In advantageous embodiment of the roundabout according to the invention, this is a classic roundabout where four roads are connected to the roundabout at regular cross-like arrangement and their imaginary axes intersect roughly in the centre of the roundabout. For this crossroad, crossing lane of the central island directs from the roundabout exit to the first road to the roundabout exit to third road, whereas the crossing lane axis is concurrent with the axis of at least the first road and parts of the central island-are-arranged-on-both-sides of the crossing lane to hinder the view from the connection to the roundabout from the first road to the connection to t e.,_* roundabout from the third road.

The roundabout according to this invention is suitable for crossings of three, five or more roads, however, for the classic crossroad with four cross-shaped roads, the benefits are highlighted most. By reducing the diameter of the roundabout to minimum while retaining traffic throughput substantial savings of investment casts are achieved.

Crossing of the priority vehicles as well as oversize load carrying vehicles through the roundabout can be controlled in a different way. In another advantageous embodiment of the roundabout according to this invention, there are at least two warning traffic lights located in the driving direction on the roundabout before roundabout exits to which ends of the crossing lane of the central island are directed, whereas the warning traffic lights are fitted with remote receivers for control from approaching priority vehicles. Simple warning traffic lights with two modes can be used for installation on the roundabout - flashing orange light and steady red light. A priority vehicle, for example RZP vehicle, may turn on the warning traffic lights to steady red light using a remote controller before approaching the roundabout and switch back to flashing orange light from the steady red light after leaving the roundabout.

The subject of the invention is also the way of smooth and safe crossing of the above-described roundabouts by the priority vehicles, substance of which is that the priority vehicle approaching the roundabout on the first road starts light and/or siren warning device on the vehicle before entering the roundabout, passes to opposite direction on the first road, enters the roundabout on exit to the first road, crosses the crossing lane in the centre island and leaves the roundabout by exit to at least third road in order from entry to the roundabout from the first road and then, light and/or siren warning devices on the vehicle may be turned off. This embodiment is particularly suitable for less busy roundabouts without warning lights installed or where the warning lights are not installed for other reasons. A limiting disadvantage of this embodiment is that some drivers may overlook the warning devices on the vehicles, react slowly or inappropriately etc.

In more advantageous embodiment of the smooth and safe crossing of the roundabout by the priority vehicles, warning traffic lights installed on the crossing are installed. The priority vehicle approaching on the first road turns on the warning traffic lights remotely before entering the roundabout, passes to opposite direction on the first road, enters the roundabout on exit to the first road, crosses the crossing lane in the centre island and leaves the roundabout by exit to at least third road in order from entry to the roundabout from the first road and then, the warning traffic lights are turned off remotely. This control of crossing the roundabout maintains maximum safety level both for the priority vehicle crews as well as for the other road users. Traffic on the roundabout is stopped for time absolutely necessary to cross the roundabout and the stop command is issued to the vehicle drivers crossing the roundabout well in advance and in a non-overlooking manner.

Another subject of the invention is the way of smooth and safe crossing through above-mentioned roundabout by a oversize load carrying vehicle, substance of which is that the traffic before at least one exit from the roundabout, to which end of the central island crossing lane is directed, is stopped by means of traffic control and the oversize load carrying vehicle, approaching on the first road, enters the roundabout via exit to the first road, passes to opposite direction on the first road, enters the roundabout on exit to the first road, crosses the crossing lane in the centre island and leaves the roundabout by exit to at least third road in order from entry to the roundabout from the first road and then the traffic on the roundabout is restored with the use of the traffic control. Crossing of the oversize load carrying vehicles occurs similarly to the priority vehicles, however, with respect to different status the vehicles have in the traffic according to relevant traffic rules.

The traffic controls may consist of any known control systems. For the oversize load -carrying vehicles— which -are- often- accompanied by service vehicles, ^" it is advantageous when the traffic control consists of at least one service vehicle, which stops the traffic before at least one exit from the roundabout to which end of crossing lane of the central island is directed, then the convey exceptional vehicle enters the roundabout via the exit, passes the crossing lane in the central circuit, leaves the roundabout and then, the service vehicle leaves the roundabout.

In one advantageous embodiment of crossing of the oversize load carrying vehicle with two service vehicles smoothly and safely, the procedure is that the front service vehicle enters the roundabout via entry from the first road, crosses the roundabout and stops traffic before exit from the roundabout to the first road. Then, the oversize load carrying vehicle approaching on the first road passes to opposite direction before the roundabout, enters the roundabout via exit to the first road and enters the central island crossing lane where it stops. Then, the rear service vehicle crosses the roundabout and leaves the same via exit to the third road. The oversize load carrying vehicle drives out of the crossing lane and leaves the roundabout via exit to the third road, where it falls in the rear service vehicle. Finally, the front service vehicle leaves the roundabout and falls in the oversize load carrying vehicle.

In other advantageous embodiment of crossing of the oversize load carrying vehicle with two service vehicles smoothly and safely, the procedure is that the front service vehicle passes to opposite direction on the first road before the roundabout, enters the roundabout with warning device turned on via the exit to the first road, i.e. in opposite direction and stops traffic before exit from the roundabout to the first road. The next steps are identical to the procedure described in previous advantageous embodiment, i.e. the oversize load carrying vehicle enters the central island crossing lane via the exit to the first road, the rear service vehicle crosses the roundabout, the oversize load carrying vehicle falls in it and finally, the front service vehicle leaves the roundabout.

The benefits of the roundabout and the way of crossing it according to the present invention are particularly that neither safety nor smoothness of the roundabout crossing for other vehicles-are-impaired7particularly because the drivers consider the central island as a compact mass hindering them to see the opposite side of the crossing and the slantwise crossing lane passing through the central island is not, in fact, seen during normal traffic. For the priority vehicles, particularly RZP vehicles, crossing of the roundabout is not only faster but also more comfortable as well without negative consequences of the side acceleration due to passing sharp bends. Symmetry of the traffic solution is maintained, i.e. all vehicles are crossing the roundabout at roughly equal bend. For the convey exceptional vehicles, the roundabout poses substantial saving of time and fuels due to potential detour of restricted crossing. For investors, the roundabout design brings high saving of capital expenditures because small-sized roundabouts can be built as well where roundabouts of larger diameters would otherwise need to be constructed for keeping the request for crossing of oversize load carrying vehicles.

Brief description of the drawings

The invention shall be explained using the drawings, where figure 1 shows schematic plan of the roundabout with warning traffic lights, with depiction of crossing the roundabout by the priority vehicle; figure 2 shows schematic plan of the roundabout with depiction of crossing the roundabout by oversize load carrying vehicle with two service vehicles in early phase of the crossing; figure 3 shows schematic plan of the roundabout with depiction of crossing the roundabout by oversize load carrying vehicle with two service vehicles in the final phase of the crossing.

Detailed description of the preferred embodiments

It is understood that the specific examples of the invention embodiment described and depicted below are given as indications and not as limitation of examples of the invention embodiment to specific cases. Persons skilled in the art shall find or be able to define either higher or lower number of equivalents to specific embodiments of the invention described herein based on routine experimentation. These equivalents are covered in the extent of the following claims below. Figure 1 shows a circuit crossroad with roundabout 1 to which four roads are connected 3, 3_, 4, 4_[ roughly shaped to a cross. Axes of the roads 3, _T, 4, 4 intersect roughly in the centre of the roundabout 1 with an increased central island 2. The roads 3, y_, 4, 4_ have two lanes each and they are expanded in the areas of connection to the roundabout Λ and the lanes for entering the roundabout and exiting from the roundabout Λ are separated by triangle-shaped partitioning islands 15. For the description purposes, numbering of the roads terminating in the roundabout in the order they follow each other when entering the roundabout Λ and crossing the roundabout Λ is used: the first road 3, the second road 4, the third road 3_, and the fourth road 4\ The third road 3J continuing from the first road 3_creat.es the main road on which increased crossing of the priority vehicles 7 or oversize load carrying vehicles 8 are forecasted.

The roundabout is designed that the central island 2 crossing lane 5 is crossing the central island 2, consisting of one traffic lane. The traffic lane passes the central island 2 slantwise so its axis is concurrent to the axis of the first road 3 as well as the second road _T, whereas one end of the crossing lane 5 is directed against the exit from the roundabout 1 to the first road 3 and the second end of the crossing lane 5 is directed against exit from the roundabout 1 to the third road 3_\ The crossing lane 5 has level dimensions equal to the roads 3, 3 , 4, 4 despite it crosses the high central island 2. This causes that the remaining parts of the central island 2, which are higher compared to the crossing lane 5 and planted with vegetation, hinders from viewing from the roundabout 1 entry from the first road 3 to the entry to the roundabout 1 from the third road 3 and the drivers are pushed to slow down like on a common roundabout.

In the roundabout embodiment described above, the priority vehicle 7 may cross the roundabout for example as follows: the priority vehicle 7, e.g. RZP, is approaching the roundabout Λ on the first road 3. The vehicle 7 crew starts light and/or siren warning device on the vehicle 7 before entering the roundabout 1. The drivers of vehicles- 2-driving-on-the-roundabout-l-stop-as wel as the-drivers of vehicles 1_1 , 13,^" and 14 approaching the roundabout on the second road 4, the third road 3 , and the fourth road 4\ The vehicle 7 drives to the opposite direction on the first road 3, passes the triangle-shaped island 15 from the left and enters the roundabout Λ not via entering from the first road 3 but the first road exit 3. Then, the vehicle 7 crosses the crossing lane 5 of the central island 2 and leaves the roundabout via exit to the third road 3 with subsequent turning the light and/or siren warning device off. The drivers of the other vehicles H, 12, 13, 14 may continue in driving.

In another embodiment, also displayed on figure 1 , the roundabout is equipped with a pair of warning traffic lights 6, 6^'. The first warning light 6 is installed on the roundabout 1 before roundabout λ exit to the first road 3. The second warning light ( is installed on the roundabout Λ before roundabout 1 exit to the third road 3\ Both warning traffic lights 6, 6^'are fitted with synchronized circuits for remote control from the priority vehicles 7 when the "orange flashing light" status can be changed to "stop" signalled by red steady light using a remote controller.

In this embodiment, the priority vehicle 7 crosses the circuit crossroad so that the priority vehicle 7, for example HZS, which approaches the roundabout on the first road 3, initiates both warning traffic lights 6, ( in advance with the use of a remote controller. The vehicles 12 on the roundabout 1 stops before the exits and the vehicles VI , 13 and 14 on the entries from the other roads 4, 3 , 4 shall stop as well. Then, the vehicle 7 drives on the first road 3 to the opposite direction around the triangle-shaped island 15, enters the roundabout A via exit to the f irst road 3, crosses the crossing lane 5 of the central island 2 and leaves the roundabout 1 via exit to the third road 3\ The warning traffic lights 6, ( are then remotely switched to "flashing orange light" and the vehicles H , 12, 13 and 14 may continue in driving.

Figure 2 and figure 3 show a roundabout identical to figure 1 but in the oversize load carrying vehicle 8 crossing mode. For the oversize load carrying vehicle 8, crossing of the roundabout may be that e.g. a policeman, driver assistant or other persons stop the traffic before the roundabout exit to the first road 3 and, if needed, before the roundabout 1 exit-to the third- road 3^' with the use of stopping targets or otherwise, including warning traffic lights. The vehicles on the roundabout Λ as well as on the entries shall stop. The oversize load carrying vehicle 8 crosses the roundabout in the same way as the priority vehicle 7 as shown in the above- mentioned embodiments, whereas the traffic on the roundabout 1 is restored back to normal mode.

In another embodiment of crossing the roundabout, the oversize load carrying vehicle 8 is escorted by one service vehicle 9. The service vehicle 9 first enters normally the roundabout Λ , crosses it and stops traffic at exit to the first road 3 on which the oversize load carrying vehicle 8 is driving. The latter drives to the opposite direction and enters the crossing lane 5 of the central island 2 where it stops. The front service vehicle 9 drives to the exit to the third road 3 where stops traffic again. The oversize load carrying vehicle 8 exits the crossing lane 5 and the roundabout via the exit to the third road 2 . The front service vehicle 9 overtakes it immediately and continues in driving.

In another embodiment of crossing the roundabout according to figure 2 and figure 3, the oversize load carrying vehicle 8 may be escorted by the front service vehicle 9 and rear service vehicle 10. Here, two alternatives of crossing the roundabout are available.

The first service vehicle 9 enters the roundabout as first via the entry from the first road 3, crosses the roundabout 1 and stops traffic before exit from the roundabout 1 to the first road 3, then the oversize load carrying vehicle 8, which approaches on the first road 3, drives to the opposite direction before the roundabout Λ , enters the roundabout 1 via the exit to the first road 3 and enters the crossing lane 5 of the central island 2 where it stops; then, the rear service vehicle 10 crosses the roundabout and leaves the roundabout Λ via exit to the third road ¥, the front service vehicle 9 crosses a part of the roundabout and stops traffic before exit from the roundabout Λ to the third road 3 and thereafter, the oversize load carrying vehicle 8 exits the crossing lane 5 and leaves the roundabout Λ via exit to the third road 3 -where-it-falls-in -the rear service vehicle 10 and finally, the front service vehicle 9 exits the roundabout and falls in the oversize load carrying vehicle 8. The second alternative of crossing the roundabout shown on figure 2 and 3 is that the front service vehicle 9 drives to the opposite direction on the first road 3 before the roundabout 1_,, enters the roundabout 1 with warning lights turned on as first right in the opposite direction via the exit to the first road 3 and stops traffic before the roundabout exit on the first road. The next steps of crossing the roundabout 1 are identical to the first alternative. The oversize load carrying vehicle 8 drives to the opposite direction on the first road 3 as well, enters the roundabout Λ via exit to the first road 3 and enters the crossing lane 5 of the central island where it slows down or stops. The second service vehicle 10 crosses the roundabout 1 normally and leaves it via exit to the third road 3J, where the oversize load carrying vehicle 8 follows and finally, the front service vehicle 9 that restores traffic on the roundabout.

Industrial applicability

The embodiments according to the invention can be applied for construction of new circuit crossroads as well as for reconstruction of current circuit crossroads for safe and smooth crossing of the priority vehicles or the oversize load carrying vehicles.

Overview of the positions used in the drawings

1 roundabout

2 central island

3 the first road

3^' the third road

4 the second road

4^' the fourth road

5 crossing lane of the central island

6 first warning traffic light

6^' second warning traffic light

7 priority vehicle

8 oversize load carrying vehicle

9 front service vehicle

10 rear service vehicle

11 a vehicle approaching the roundabout on the second road 4

12 a vehicle driving on the roundabout

13 a vehicle approaching the roundabout on the third road 3^'

14 a vehicle approaching the roundabout on the fourth road 4^'

15 triangle-shaped island

Claims

The circuit crossroad for safe and smooth passing of the priority vehicles (7) or the oversize load carrying vehicles (8) consisting of the roundabout (1) with the high central island (2) where at least three two-lane roads (3,3^',4,4^') are connected to the roundabout (1) characterized by that in the central island (2) there is a crossing lane (5) of the central island (2) consisting of at least one crossing lane slantwise across the central island (2) from exit from the roundabout (1) to the first road (3) to the roundabout (1) exit to at least third road (3^') in the order following from the entry to the roundabout (1) on the first road (3).

The roundabout according to claim 1 characterized by that four roads ( 3,

3^',4,

4^') are connected to the roundabout (1 ) at regular cross-like arrangement and their imaginary axes intersect roughly in the centre of the roundabout (1 ) and the crossing lane (5) of the central island (2) directs from the roundabout (1) exit to the first road (3) to the roundabout (1) exit to third road (3^'), whereas the crossing lane (5) axis is concurrent with the axis of at least the first road (3) and parts of the central island (2) are arranged on both sides of the crossing lane (5) to hinder view from the connection to the roundabout (1) from the first road (3) to the connection to the roundabout (1) from the third road (3^').

The roundabout according to claim 1 or 2 characterized by that there are at least two warning traffic lights (6,6^') located in the driving direction on the roundabout (1) before roundabout (1) exits to which ends of the crossing lane (5) of the central island (2) are directed, whereas the warning traffic lights (6,6^') are fitted with remote receivers for control from approaching priority vehicles (7).

The method of smooth and safe crossing of the roundabout described in claim 1 or 2 by the priority vehicles (7) characterized by that the priority vehicle (7) approaching the roundabout on the first road (3) starts light and/or siren warning device on-the-vehicle-(7)-before-entering the- roundabout passes to opposite direction on the first road (3), enters the roundabout (1) on exit to the first road (3), crosses the crossing lane (5) in the centre island (2) and leaves the roundabout (1) by exit to at least third road (3^') in order from entry to the roundabout (1) from the first road (3) and then, light and/or siren warning devices on the vehicle (7) may be turned off.

5. The method of smooth and safe crossing of the roundabout described in claim 3 by the priority vehicles (7) characterized by that the priority vehicle (7) approaching on the first road (3) turns on the warning traffic lights (6, 6^') remotely before entering the roundabout (1 ), passes to opposite direction on the first road (3), enters the roundabout (1 ) on exit to the first road (3), crosses the crossing lane (5) in the centre island (2) and leaves the roundabout (1) by exit to at least third road (3^') in order from entry to the roundabout (1) and then, the warning traffic lights (6, 6^') are turned off remotely.

6. The method of smooth and safe crossing of the roundabout described in at least of the claims 1 to 3 by the oversize load carrying vehicles (8) characterized by that the traffic before at least one exit from the roundabout (1 ), to which end of the central island (2) crossing lane (5) is directed, is stopped by means of traffic control and the oversize load carrying vehicle (8), approaching on the first road (3), enters the roundabout (1) via exit to the first road (3), passes to opposite direction, enters the roundabout (1) on exit to the first road (3), crosses the crossing lane (5) in the centre island (2) and leaves the roundabout (1) by exit to at least third road (3^') in order from entry of the oversize load carrying vehicle (8) to the roundabout (1 ) from the first road and then the traffic on the roundabout (1) is restored with the use of the traffic control.

7. The method of smooth and safe crossing of the roundabout according to claim 6 characterized by that the traffic control consists of at least one service vehicle (9, 10), which stops the traffic before at least one exit from the roundabout (1 ) to which end of crossing lane (5) of the central island (2) is directed, then the convey exceptional vehicle (8) enters the roundabout (1) via the exit, passes the crossing lane (5) in the central circuit, leaves the roundabout (1) and then, the service vehicle (9, 10) leaves the roundabout (1).

8. The method of smooth and safe crossing of the roundabout according to claim 7 characterized by that the oversize load carrying vehicle (8) is escorted by the front service vehicle (9) and rear service vehicle (10), where the front service vehicle (9) enters the roundabout (1) via entry from the first road (3), crosses the roundabout (1 ) and stops traffic before exit from the roundabout (1) to the first road (3); then, the oversize load carrying vehicle (8) approaching on the first road (3) passes to opposite direction before the roundabout (1), enters the roundabout (1) via exit to the first road (3) and enters the central island (2) crossing lane (5) where it stops; then, the rear service vehicle (10) crosses the roundabout (1) and leaves the same via exit to the third road (3^'); subsequently, the oversize load carrying vehicle (8) drives out of the crossing lane (5) and leaves the roundabout (1) via exit to the third road (3^'), where it falls in the rear service vehicle (10). Finally, the front service vehicle (9) leaves the roundabout (1) and falls in the oversize load carrying vehicle (8).

9. The method of smooth and safe crossing of the roundabout according to claim 7 characterized by that the oversize load carrying vehicle (8) approaching on the first road (3) is escorted by the front service vehicle (9) and rear service vehicle (10), whereas the front service vehicle (9) passes to the opposite direction on the first road (3) before the roundabout (1) with light warning system on and stops traffic before the roundabout (1) exit to the first vehicle (3); then the oversize load carrying vehicle (8) passes to the opposite direction on the first road (3) before the roundabout (1), enters the roundabout (1) via exit to the first road (3) and enters the crossing lane (5) of the central island (2), where it stops or slows down and the second service vehicle (10) enters the roundabout (1) via the entry from the first road (3) and leaves it via exit to the third road (3^'); subsequently, the oversize load carrying vehicle (8) exits the crossing lane (5) and leaves the roundabout (1 ) via exit to the third road (3^') where falls in the rear service vehicle (10) and finally, the front service vehicle (9) leaves the roundabout and falls in the oversize load carrying vehicle (8).